tretinoin and retinol-acetate

A wide range of cosmeceutical products are available on the market currently, but evidence to support their use is often lacking in the literature. Specifically, there is a substantial amount of evidence supporting the efficacy of tretinoin in photoaging, but the evidence supporting retinoid-based cosmeceuticals remains sparse. The authors review the current data in the literature related to vitamin A-derived cosmeceutical products and conclude that cosmeceuticals containing retinaldehyde have been shown in large randomized, controlled trials to have the most beneficial effect on aging skin.

Topics: Administration, Topical; Antioxidants; Cosmetics; Dermatologic Agents; Diterpenes; Humans; Keratolytic Agents; Randomized Controlled Trials as Topic; Retinaldehyde; Retinoids; Retinyl Esters; Skin Aging; Tretinoin; Vitamin A

Topics: Adjuvants, Immunologic; Animals; Breast Neoplasms; Carcinogens; Cricetinae; Diterpenes; Female; Humans; Keratoacanthoma; Lung Neoplasms; Male; Mice; Neoplasms; Prostatic Neoplasms; Rats; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

The induction of ornithine decarboxylase (ODC) during G1 phase of the cell cycle appears to be universal and essential for cell cycle progression. This induction has been demonstrated in at least 23 cell types in response to various growth stimuli. Further, specific inhibitors of ODC added to several of these cell lines resulted in inhibition of cell proliferation. The studies of the effects of retinoids to inhibit Chinese hamster ovary (CHO) cell growth indicate that the cells are blocked in G1 of cell cycle, and that there is a concentration-dependent inhibition of ODC induction. Retinoids only inhibit the induction of ODC activity when added in the first 2-3 hr of G1 progression. It is postulated that ODC induction is a requirement for G1 progression and that the antiproliferative properties of retinoids are related to the specific ability to inhibit this expression. Since retinoids do not dramatically alter the rate of protein synthesis, their ability to inhibit ODC may be related to their ability to inhibit messenger RNa synthesis for ODC.

Topics: Animals; Carboxy-Lyases; Cell Cycle; Cell Line; Cricetinae; Cricetulus; Cyclic AMP; Diterpenes; Enzyme Activation; Enzyme Induction; Female; Humans; Kinetics; Ornithine Decarboxylase; Ovary; Protein Kinases; Retinaldehyde; Retinyl Esters; Tretinoin; Vitamin A

The addition of growth factors and vitamins enhances goat embryonic development in vitro. However, few attempts have been reported trying to identify supplementation regimens for oocyte maturation or embryo culture with additive properties. The present report was aimed to evaluate if retinoids [0.3 μM retinyl acetate (RAc) and 0.5 μM 9-cis-retinoic acid (RA)] supplementation during goat oocyte maturation and retinoids and/or 50 ng mL-1 IGF-I during embryo culture synergically enhanced embryonic development while diminishing the incidence of apoptosis. All combinations of RAc and RA treatment produced blastocysts with similar efficiencies, while IGF-I enhanced embryos yields irrespectively of retinoid addition. Moreover, retinoids and IGF-I supplementation showed similar caspase activity or DNA fragmentation indexes in blastocysts. In conclusion, supplementation with retinoids and IGF-I during goat embryo culture enhances blastocysts development without synergic reduction of apoptosis.

Topics: Alitretinoin; Animals; Apoptosis; Blastocyst; Cells, Cultured; Culture Media; Diterpenes; Embryo Culture Techniques; Female; Fertilization in Vitro; Goats; In Vitro Oocyte Maturation Techniques; Insulin-Like Growth Factor I; Oocytes; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

Human serum albumin (HSA), a major plasma protein and plasma-derived therapeutic, interacts with a wide variety of drugs and native plasma metabolites. In this study the interactions between HSA and small lipophilic molecules all-trans retinoic acid (RA), all-trans retinaldehyde (retinal, RAL) and all-trans retinyl acetate (RAC) were investigated by UV-vis absorption spectroscopy, fluorescence spectroscopy and circular dichroism (CD). This paper focuses on investigation of the interactions between HSA and RA by the visible CD. RAL and RAC were used in this study due to their structural identity to RA to elucidate the importance of the end functional group for the complex formation. Our data demonstrate that RA specifically binds to HSA in a stable non-covalent complex at least at two internal binding sites with close but distinct affinities. Upon titration of HSA with RA, visible CD spectra clearly demonstrate the appearance of a well-defined induced positive Cotton Effect (CE) around 350 nm. Beyond ligand-to-protein ratio of 0.8 and up to saturation (2.0), CD exhibits two major bands of opposite signs, suggesting exciton coupling between the chromophore molecules in the protein interior. The fluorescence quenching data suggest proximity of the primary RA binding site to tryptophan (W214). RAC shows a weak association with HSA with stoichiometry close to that of RA, while interactions of RAL with HSA proceed non-specifically at multiple sites. Contrary to RA, the adducts of HSA with RAC and RAL do not show any induced chirality, thus indicating that despite their high structural similarity to RA, both compounds do not appear to occupy the internal binding sites, but associate with the protein exterior.

Topics: Circular Dichroism; Diterpenes; Fluorescence; Humans; Retinaldehyde; Retinyl Esters; Serum Albumin; Spectrophotometry, Ultraviolet; Tretinoin; Vitamin A

An antagonistic interaction between retinol and calciferol has been established. However, the mechanism by which this antagonism occurs is unclear. One possibility is that retinol affects the metabolism of calciferol. To investigate this hypothesis, retinol- and calciferol-depleted rats were given various amounts of ergocalciferol, cholecalciferol, 1alpha,25-dihydroxycholecalciferol [1,25(OH)2D3], or 24,24-difluoro-1alpha,25-dihydroxycholecalciferol [24-F2-1,25(OH)2D3] in combination with various amounts of retinyl acetate or all-trans retinoic acid (ATRA) in a series of studies. Rats administered 1720 or 3440 microg retinyl acetate once every 3 d for 33 d in combination with 25.8 ng ergocalciferol or 25 ng cholecalciferol every 3 d had lower serum calcium and greater serum phosphorus concentrations than rats fed 0 or 11.4 mug retinyl acetate every 3 d. In addition, rats fed 400 microg ATRA/d in combination with 25.8 ng ergocalciferol every 3 d, 25 ng cholecalciferol every 3 d, 2-5 ng 1,25(OH)2D3/d, or 0.5-1 ng 24-F2-1,25(OH)2D3/d had significantly lower serum calcium and higher serum phosphorus concentrations than rats not given ATRA in the diet. Therefore, both retinyl acetate and ATRA are able to antagonize the action of ergocalciferol and cholecalciferol in vivo. Additionally, ATRA antagonizes the in vivo action of 1,25(OH)2D3 and an analog, 24-F2-1,25(OH)2D3, that cannot be 24-hydroxylated. Together, these results suggest that retinol does not antagonize the action of calciferol by altering the metabolism of calciferol or 1,25(OH)2D3, but does so by another mechanism.

Topics: Animals; Calcitriol; Calcium; Diterpenes; Ergocalciferols; Male; Phosphorus; Rats; Rats, Sprague-Dawley; Retinyl Esters; Tretinoin; Vitamin A

An increase of human monoclonal antibody production caused by retinyl acetate and retinoic acid was influenced by the fusion partner rather than the original B lymphocyte used for the human hybridoma generation. Retinoid response of human hybridomas may be at least related to retinoid X receptor-alpha gene expression, which seemed to originate from their fusion partner.

Topics: Adult; Antibodies, Monoclonal; Antibodies, Neoplasm; Antibody Formation; Cell Fusion; Diterpenes; Gene Expression; Humans; Hybridomas; Lung Neoplasms; Receptors, Retinoic Acid; Retinyl Esters; Tretinoin; Tumor Cells, Cultured; Vitamin A

Leptin is a peptide hormone that appears critical in regulating Fat metabolism. Recently, circulating leptin levels were reported higher in patients with alcoholic cirrhosis. In health, hepatic stellate cells store retinoids, but following liver injury they transdifferentiate into myofibroblast-like cells with loss of the retinoid stores. Leptin expression was demonstrated by detection of leptin mRNA by RT-PCR analysis and by immunohistochemistry viewed with confocal microscopy in transdifferentiated stellate cells after 14 days, or more, of culture. Leptin expression was not found in freshly isolated quiescent stellate cells. Leptin expression was not demonstrated in freshly isolated or cultured Kupffer cells. Treatment of activated stellate cells with either 1 microM retionic acid or 10 microM retinol acetate resulted in the inhibition of leptin mRNA expression. The observation that activated stellate cells in culture can express leptin has implications for understanding adipocyte biology in liver disease and treatment of malnutrition in cirrhotics.

Topics: Animals; Cell Differentiation; Cell Separation; Cells, Cultured; Diterpenes; Leptin; Liver; Male; Obesity; Protein Biosynthesis; Proteins; Rats; Rats, Sprague-Dawley; Retinyl Esters; RNA, Messenger; Tretinoin; Vitamin A

Retinoic acid, a metabolite of retinol, is formed in the skin of various species.. Formation rates have not been determined in a dynamic skin perfusion model which may show the dehydrogenation of retinol to be rate limited.. (all-trans-) Retinol acetate, retinol, or retinoic acid was applied dermally with isopropyl myristate. The ears were single-pass perfused with 6% hetastarch or 5% bovine serum albumin in the buffer solution. The effluent was analyzed by HPLC for these substances.. No ester hydrolysis of retinol acetate was observed, nor did this substrate appear in the effluent. Retinol or retinoic acid were detected in the effluent. The absorption rate was linearly related to the dermally applied concentration density. The absorption rate of retinoic acid was 70 times larger than that for retinol. The formation rate of retinoic acid from retinol was rate limited (apparent Vmax: 0.08 pmol/min/cm2 skin).. Since retinoic acid is a recognized pharmacologically active ingredient in the skin, the dehydrogenation of retinol or retinal was also observed in the effluent of this skin perfusion model. The percutaneous retinol adds to the endogenous pool of retinoic acid by cytosolic dehydrogenation or microsomal oxidation elsewhere. The steady-state absorption rate of 0.1% retinoic acid in isopropyl myristate, referred to 500 cm2 of the human skin, would contribute about 20% of the daily requirement of vitamin A, without increase in endogenous retinoic acid plasma concentration.

Topics: Administration, Topical; Animals; Chromatography, High Pressure Liquid; Diterpenes; Ear, External; Indicators and Reagents; Keratolytic Agents; Perfusion; Rabbits; Retinyl Esters; Solubility; Spectrophotometry, Ultraviolet; Stereoisomerism; Tretinoin; Vitamin A

Cyclooxygenase-2 expression is up-regulated in transformed cells and tumors. Because this enzyme catalyzes the synthesis of prostaglandins, strategies aimed at suppressing its expression may prove useful in preventing or treating cancer. We investigated the ability of retinoids to suppress phorbol ester-mediated induction of cyclooxygenase-2 in human oral epithelial cells. Treatment with phorbol myristate acetate (PMA) resulted in approximately a 3-fold increase in the production of prostaglandin E2 (PGE2). Retinoids [all-trans-retinoic acid (RA), 13-cis-RA, and retinyl acetate] markedly suppressed PMA-mediated increases in amounts of cyclooxygenase-2 (Cox-2) and the production of PGE2. Retinoids also suppressed the induction of Cox-2 mRNA by PMA. Nuclear run-offs revealed increased rates of Cox-2 transcription after treatment with PMA; this effect was inhibited by all-trans-RA. Transient transfection experiments showed that PMA caused about a 2-fold increase in Cox-2 promoter activity, an effect that was suppressed by all-trans-RA. Our data indicate that treatment of oral epithelial cells with PMA is associated with enhanced transcription of Cox-2 and increased production of PGE2. These effects of PMA were inhibited by retinoids.

Topics: Anticarcinogenic Agents; Biotransformation; Carcinoma, Squamous Cell; Cyclooxygenase 2; Dinoprostone; Diterpenes; Enzyme Induction; Gene Expression Regulation, Neoplastic; Humans; Isoenzymes; Isotretinoin; Membrane Proteins; Mouth Neoplasms; Neoplasm Proteins; Peroxidases; Prostaglandin-Endoperoxide Synthases; Retinyl Esters; Tetradecanoylphorbol Acetate; Transcription, Genetic; Tretinoin; Tumor Cells, Cultured; Vitamin A

Aging is accompanied by troubles resulting from changes in hormonal and nutritional status. Therefore, the abundance of mRNA coding for triiodothyronine (TR) and retinoic acid (RA) nuclear receptors was studied in the brain of young, adult and aged (2.5, 6 and 24 months, respectively) rats. In the brain of aged rats, there was a lower abundance of TR and RAR mRNA and a lower activity of tissue transglutaminase (tTG), an enzyme the gene of which is a target for retinoids. Administration of RA in these rats restored TR and RAR mRNA and the activity of tTG in the brain. The importance of these observations to the function of the aged brain is discussed.

Topics: Age Factors; Aging; Animals; Brain; Diterpenes; Intubation, Gastrointestinal; Male; Rats; Rats, Wistar; Receptors, Retinoic Acid; Receptors, Thyroid Hormone; Retinyl Esters; RNA, Messenger; Tretinoin; Vitamin A

Topics: Anticarcinogenic Agents; Antineoplastic Agents; Blotting, Northern; Blotting, Western; Carcinogens; Carcinoma, Squamous Cell; Cyclooxygenase 2; Dinoprostone; Diterpenes; Gene Expression Regulation, Enzymologic; Humans; Isoenzymes; Isotretinoin; Membrane Proteins; Peroxidases; Phorbol Esters; Prostaglandin-Endoperoxide Synthases; Retinoids; Retinyl Esters; Tretinoin; Tumor Cells, Cultured; Vitamin A

High-performance liquid chromatography (HPLC)-electrospray mass spectrometry (LC-MS) was used to analyze vitamin A-active retinoids including retinoic acid, retinol, retinal, and retinyl acetate. Unlike previous LC-MS methods such as negative ion electron capture chemical ionization, no derivatization of retinoic acid was required. HPLC separations were carried out on a C30 reversed phase column with gradient elution using mobile phases containing water, methanol, and methyl-tert-butyl ether. Ammonium acetate (5 mM) was added to the mobile phase to facilitate ion pair formation during reversed phase HPLC of retinoic acid, and acetic acid (0.5% v/v) was added to the mobile phase to enhance protonation during LC-MS analysis of nonacidic retinoids. During negative ion electrospray, retinoic acid formed abundant deprotonated molecules, [M-H]-, of m/z 299 without significant fragmentation. Although retinol, retinal, and retinyl acetate did not ionize during negative ion electrospray, the positive ion electrospray mass spectra of these retinoids showed an abundant protonated molecule of m/z 285 for retinal and base peaks of m/z 269 corresponding to elimination of water or acetic acid from the protonated molecules of retinol or retinyl acetate, respectively. No ions from retinoic acid were detected during positive ion electrospray. Limits of detection for retinoic acid, retinal, retinol, and retinyl acetate were 23 pg, 1.0 ng, 0.5 ng, and 10 ng, respectively.

Topics: Diterpenes; Gas Chromatography-Mass Spectrometry; Ions; Retinaldehyde; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

The teratogenic potencies of the all-trans isomers of retinoic acid (RA), 3,4-didehydroretinyl acetate (A2), and retinyl acetate (A1) were compared. Groups of eight timed-pregnant Sprague-Dawley rats were administered single equimolar doses (3.5-352 mumol/kg BW) of the retinoids orally in oil on day 8.5 of pregnancy, and dams and fetuses were sacrificed on day 19. The relative teratogenicity and embryolethality of the three tested retinoids were: RA > A2 > A1. The no-effect level of RA and A2 was 3.5 mumol/kg BW and of A1 was 35 mumol/kg BW. Whereas the adverse effects of RA and A1 were dose dependent, A2 showed biphasic effects, with a peak of embryolethality at 35 mumol/kg BW. Dams also exhibited weight loss and other toxic manifestations from doses of A2 and Ra > or = 35 mumol/kg BW. In dosed dams, (1) Liver concentrations of A1 and A2 increased with the doses of A1 and A2, respectively, (2) RA had little effect on liver A1 except for an increase at the highest toxic dose, and (3) A2 showed a sparing effect on liver A1. RA, although not detected in fetuses from dams treated with A1, was present in significant concentrations (0.5-4.1 nmol/g liver) in fetuses from dams treated with A2. The biphasic change in embryolethality with the dose of A2 correlates with this enhanced concentration of fetal RA. We hypothesize that the actual teratogen in the fetuses of A2-dosed dams is RA. A2 might induce this biphasic effect by inhibiting the catabolism of RA at lower doses and its formation at higher doses.

Topics: Animals; Diterpenes; Female; Fetal Resorption; Isomerism; Liver; Organ Size; Pregnancy; Rats; Rats, Sprague-Dawley; Retinyl Esters; Teratogens; Tretinoin; Vitamin A

Biological functions of retinoids in the vertebrate retina include the role of 11-cis retinaldehyde as visual pigment chromophore, and possible effects of retinoic acid in histogenesis and cell survival. Qualitative and quantitative regulation of retinoid availability for these complex processes could involve several cell types, including retinal pigment epithelium, Müller glia and retinal photoreceptors and non-photoreceptor neurons; their relative contributions, however, have not been fully elucidated. Using purified cultures, we have carried out a study of cell-type-specific metabolism and storage of retinoids in chick embryo retinal photoreceptors and other neuronal cells, as compared to those of retinal glia. Retinal glia were found to synthesize both retinoic acid and retinyl esters, and to hydrolyse the latter; they also displayed retinol dehydrogenase activities. Cultured neurons and photoreceptors also synthesized and hydrolysed retinyl esters; their capacity for retinaldehyde synthesis from a retinol or retinyl ester substrate suggested the presence of retinol dehydrogenase activity. Retinoic acid was not synthesized in differentiated neuronal cultures, although some synthesis was detectable at early culture stages when the cells were still morphologically undifferentiated. These findings indicate that cell-type-specific metabolic activities are expressed during retinal cell differentiation in vitro, and that embryonic retinal photoreceptors and nonphotoreceptor neurons are active participants in the metabolism and storage of retinoids.

Topics: Animals; Cells, Cultured; Chick Embryo; Diterpenes; Neuroglia; Neurons; Photoreceptor Cells; Retina; Retinaldehyde; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

The effects of retinoic acid and retinol acetate on gap junctional communication were examined in two in vitro tests. Rat liver epithelial cell line IAR 203 was used for dye transfer assays, and hamster lung fibroblast V79 cells were used for metabolic cooperation assays. A reversible dose-dependent inhibition of dye transfer was detected after a 1-hr treatment with retinoic acid or retinol acetate at concentrations ranging from 10 to 50 microM. On the other hand, enhancement of dye transfer was observed after a 24-hr treatment with retinoic acid at 0.1 microM. A dose-dependent inhibition of metabolic cooperation was obtained with retinoic acid at noncytotoxic concentrations ranging from 5 to 50 microM. Retinoids and TPA (1 ng/ml) acted synergistically in their inhibition of cell communication. Thus, the assays appear to be complementary: the dye transfer assay was useful in studying the time course and the reversibility of the inhibition or enhancement of dye transfer, whereas the metabolic cooperation assay was effective in quantifying the inhibitory effect of TPA or retinoids and interactions between them.

Topics: Animals; Biological Transport; Cell Communication; Cell Count; Cell Line; Coloring Agents; Cricetinae; Diterpenes; Fibroblasts; Gap Junctions; Liver; Rats; Retinyl Esters; Stem Cells; Tretinoin; Vitamin A

Although it has been suggested that retinoids regulate Ito cell proliferation and collagen synthesis, little is known about the ability of Ito cells to respond to retinoids in vivo. Because retinoids may mediate their molecular effects through nuclear receptors, Ito cells were examined for the presence of one of these receptors, nuclear retinoic acid receptor-beta. The modulation of nuclear retinoic acid receptor-beta expression was also studied during cell culture and hepatic fibrogenesis. Northern hybridization analysis revealed that Ito cells freshly isolated from normal rat liver contained nuclear retinoic acid receptor-beta messenger RNA at levels significantly higher than those found in other hepatic cell types. Ito cells also contained messenger RNA for two other nuclear retinoic acid receptors, nuclear retinoic acid receptor-alpha and nuclear retinoic acid receptor-gamma. Using an antibody to human nuclear retinoic acid receptor-beta, the nuclear presence of this receptor was demonstrated in normal Ito cells. In contrast, Ito cells cultured for at least 7 days had no detectable messenger RNA or nuclear staining for nuclear retinoic acid receptor-beta despite a 20 +/- 5-fold increase in the messenger RNA level of another retinoid binding protein, cellular retinol binding protein. Analysis of Ito cells isolated from rats with carbon tetrachloride-induced hepatic fibrosis revealed an 81% +/- 3% decrease in nuclear retinoic acid receptor-beta messenger RNA levels in these cells when compared with normal Ito cells. No difference in the messenger RNA levels of cellular retinol binding protein was found in Ito cells isolated from either normal or fibrotic liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Carrier Proteins; Cell Nucleus; Cells, Cultured; Diterpenes; Liver; Liver Cirrhosis, Experimental; Male; Nucleic Acid Hybridization; Rats; Rats, Inbred Strains; Receptors, Retinoic Acid; Retinyl Esters; RNA, Messenger; Tretinoin; Vitamin A

Recently, we have reported that retinoic acid (RA), similarly to retinol acetate, is able to reinitiate spermatogenesis in vitamin A-deficient rats. Here, we investigated the expression of RA receptors RAR alpha, RAR beta, RAR gamma, and retinoid X receptor RXR alpha by Northern blot analysis of poly(A)+ RNA of testes of vitamin A-deficient rats before and after reinitiation of spermatogenesis induced by injection of retinol acetate or RA and testes of 21-day-old and 10-week-old normal rats. In the testis of vitamin A-deficient rats 1.9-, 2.8-, and 3.8-kilobase (kb) transcripts of RAR alpha; 2.8- and 3.3-kb transcripts of RAR beta; 1.8-, 2.8-, and 3.4-kb transcripts of RAR gamma; and two transcripts of RXR alpha of 2.5 and 4.8 kb are expressed. When vitamin A-deficient rats receive RA or retinol acetate, a 3-fold increase in the amount of poly(A)+ RNA per testis can be observed after 8 h, while the amounts of glyceraldehyde-3-phosphate dehydrogenase and sulfated glycoprotein-1 mRNA hardly change. Also, the expression of several transcripts of each RAR type is significantly increased from 1.8- up to 3.6-fold. Moreover, additional transcripts of RAR beta and RXR alpha (1.8 and 1.0 kb, respectively) can be detected. In the testes of 21-day-old rats, three transcripts of each RAR type and two RXR alpha transcripts are expressed. In contrast, in the normal adult rat testis the expression of all RARs, if present, is lower than that in the 21-day-old rat testis or the adult vitamin A-deficient rat testis. The expression of all transcripts of each RAR in the testis of 21-day-old rats shows great similarity with the expression in the testis of the vitamin A-deficient rat after replacement of retinol acetate or RA. These changes in expression indicate that RARs and RXR alpha may play a role in the process of proliferation and differentiation of A spermatogonia, which is induced in vitamin A-deficient rats shortly after replacement of RA or retinol acetate.

Topics: Animals; Blotting, Northern; Carrier Proteins; Diterpenes; Gene Expression; Male; Rats; Rats, Inbred Strains; Receptors, Retinoic Acid; Retinoids; Retinyl Esters; RNA, Messenger; Spermatogenesis; Testis; Transcription, Genetic; Tretinoin; Vitamin A; Vitamin A Deficiency

The pharmacokinetics of three 13-cis-retinoic acid formulations were studied after intraperitoneal (ip) administration to rats. Rats were given ip injections of 2.5 mg of 13-cis-retinoic acid per 360 g of body weight; the drug was administered as an alkaline solution, suspended in corn oil, or as a mixture with polysorbate 80. The alkaline solution was also given intravenously (iv) via the tail vein as a control. The mean elimination rate constant, calculated from data from iv administration, was 0.72 +/- 0.088 h-1 (r = 0.988). The peak concentration in plasma and the time to reach this maximum were 14 mg/L and 0.5 h, 22 mg/L and 2 h, and 10 mg/L and 1 h for the drug administered as an alkaline solution, suspended in corn oil, and as a mixture with polysorbate 80, respectively. The areas under the concentration-time curve (concentration in plasma versus time) were 34.9 +/- 8.78 mg.h/L for the iv dose and 34.1 +/- 9.97, 62.4 +/- 32.3, and 25.9 +/- 12.0 mg.h/L for the ip doses of alkaline solution, suspension in oil, and mixture with polysorbate 80, respectively. Because of the rapid increase of concentration in plasma, which is identical to that of the iv profile, and the ease of its handling and preparation, the ip administered alkaline solution is the preferable formulation.

Topics: Animals; Biological Availability; Chemistry, Pharmaceutical; Corn Oil; Diterpenes; Injections, Intraperitoneal; Male; Pharmaceutical Vehicles; Polysorbates; Rats; Rats, Inbred Lew; Retinyl Esters; Tretinoin; Vitamin A

Retinyl acetate (RA) dramatically increased the production of early (d16) erythroid colonies in vitro by circulating human progenitor cells growing in an improved serum-free (SF) medium. In the absence of either erythropoietin (Epo) or insulin-like growth factor I (IGF-I), RA alone was able to induce the hemoglobinization of cells in these erythroid colonies. RA synergized with Epo or with IGF-I to yield increased numbers of well-hemoglobinized early colonies. In the presence of defined burst promoting activity (BPA) provided by recombinant human interleukin 3 (rHuIL-3) and hemin, RA and all-trans-retinoic acid (ATRA) were identical with respect to their differentiation-inducing function for early erythroid colonies. ATRA increased the number of these colonies in a concentration-dependent manner, with maximal stimulation (3.5-fold) occurring at 30 nM in the presence of 5.5 ng/ml IL-3, 0.1 mM hemin, 3.0 U/ml Epo and 30 nM IGF-I. This appears to be the first demonstration of erythropoietic activity of two metabolic derivatives of vitamin A in SF medium.

Topics: Cells, Cultured; Colony-Forming Units Assay; Culture Media, Serum-Free; Diterpenes; Erythrocytes; Erythroid Precursor Cells; Erythropoiesis; Erythropoietin; Hemin; Humans; Insulin-Like Growth Factor I; Interleukin-3; Recombinant Proteins; Retinyl Esters; Tretinoin; Vitamin A

Vitamin A-deficient (A-) mice produce poor IgG antibody responses due to a helper T cell dysfunction. We performed retinoid repletion studies to determine the minimum dietary retinyl acetate dose and the most active retinoid for supporting immune function. Dietary retinyl acetate repletion at 2 (R2 group) or 4 (R4 group) microgram/g diet restored serum retinol in A- mice to vitamin A-sufficient (A+) control levels within 24 h. However, in R4 mice, liver retinyl palmitate was restored about twofold faster than in R2 mice; liver retinyl palmitate reached A+ control levels by d 30 in R4 mice but not in R2 mice. We challenged the mice with antigen 24 h post repletion; the R4 mice gave an IgG1 response equal to that of A+ controls, but the R2 mice were comparable with the A- controls. We also compared four retinoids for IgG1 response restoration in vitro; 1 nmol/L retinoic acid fully repleted A- cell IgG1 responses and helper T cell frequencies to the unsupplemented A+ control levels. Retinoic acid was at least 10-fold more active than retinyl acetate or retinaldehyde, and 100-fold more active than retinol. Collectively, our results suggest that retinoic acid is probably the physiologically important metabolite for sustaining IgG immune responses in vivo. We discuss the possible relationship between liver retinyl palmitate levels and availability of retinoic acid to support immune function.

Topics: Animals; Antibody Formation; B-Lymphocytes; Cells, Cultured; Diet; Diterpenes; Female; Immunoglobulin G; Male; Mice; Retinyl Esters; T-Lymphocytes; Tretinoin; Vitamin A; Vitamin A Deficiency

Retinoids exhibit a wide spectrum of activities, including antiinflammatory properties. We have investigated the effect of retinoic acid (RA) and retinyl acetate (RAc) on the production of reactive oxygen metabolites and the release of lysosomal enzymes by human polymorphonuclear leukocytes (PMN). Incubation of PMN with RAc or RA (1-100 microM) caused a dose-dependent inhibition (upto 90%) in O2- production and chemiluminescence induced by phorbol myristate acetate (PMA), N-formyl-methionyl-leucyl-phenylanaline (fMLP), opsonized zymosan or ionophore A23187. Both retinoids (1-100 microM) also inhibited, in a dose-dependent way, degranulation induced by fMLP (upto 85% at the highest concentration of RA). These inhibitory effects appear irreversible, since they persist after the drugs are removed and the cells washed before stimulation. Inhibitors of cyclo-oxygenase activity such as acetylsalicyclic acid and indomethacin did not influence the effects of RAc. In contrast, BW755, an inhibitor of both cyclooxygenase and lipoxygenase, reversed the inhibitory action of RAc, suggesting that the effect of retinoids occurs possibly through the mediation of lipoxygenase products. The modulation of PMN oxidative metabolism and degranulation might help explain the antiinflammatory properties of retinoids.

Topics: Calcimycin; Cyclooxygenase Inhibitors; Cytoplasmic Granules; Diterpenes; Humans; Lipoxygenase Inhibitors; Luminescent Measurements; Lysosomes; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Respiratory Burst; Retinyl Esters; Superoxides; Tetradecanoylphorbol Acetate; Tretinoin; Vitamin A; Zymosan

Retinoids are known to modulate several functions of mononuclear phagocytes. We have studied the effect of retinyl acetate (RAc) and retinoic acid (RA) on the production of procoagulant activity (PCA) by human peripheral blood mononuclear cells stimulated with endotoxin (1 microgram/ml, 4 or 20 h at 37 degrees C). Both compounds caused a dose-dependent reduction in the expression of cell-associated PCA (from 86 to less than 10% of control in the range of concentration comprised between 0.1 and 100 microM). This effect was also observed when the cells were exposed to retinoids for 10 min and washed before challenge with endotoxin, indicating that it is rapid and irreversible. In contrast, incubation of RAc or RA for 3 h at 37 degrees C with cells that have been already stimulated with endotoxin (20 h at 37 degrees C) remained without influence on cell PCA. The inhibitory action of retinoids was also observed when monocyte-enriched (greater than 85%) preparations or highly purified monocyte-derived macrophages (greater than 99%) were used instead of whole mononuclear cells. BW755C, an inhibitor of cyclo-oxygenase and lipoxygenase, reversed the inhibitory effect of retinoids, whereas acetylsalycilic acid, an inhibitor of cyclo-oxygenase, was inactive, suggesting the involvement of a lipoxygenase product. The inhibition of monocyte/macrophage PCA production and the subsequent reduction of cell potential for fibrin deposition might represent one of the mechanisms whereby retinoids exert their antiinflammatory and immunomodulatory activities.

Topics: Blood Coagulation; Diterpenes; Humans; In Vitro Techniques; Leukocytes, Mononuclear; Phagocytes; Retinyl Esters; Tretinoin; Vitamin A

The binding of retinol, retinyl acetate, retinoic acid and beta-carotene to native, esterified and alkylated beta-lactoglobulin was followed by quenching of tryptophan fluorescence. Three studied retinoids bind to native or modified beta-lactoglobulin in 1:1 molar ratios, with apparent dissociation constants in the range of 10(-8) M. The maximum tryptophan fluorescence quenching of unmodified beta-lactoglobulin by beta-carotene is observed at the ligand/protein ratio of 1:2. Esterification and alkylation of beta-lactoglobulin shift the ratio of beta-carotene/protein to 1:1. In all the cases, except for retinoic acid binding to N-ethyllysyl-BLG, the performed chemical modifications of beta-lactoglobulin enhance protein binding affinity. Measured apparent dissociation constants of beta-carotene complexes with native and modified beta-lactoglobulin are an order of magnitude lower from binding constants of other studied retinoids.

Topics: beta Carotene; Carotenoids; Diterpenes; Kinetics; Lactoglobulins; Protein Binding; Retinoids; Retinyl Esters; Spectrometry, Fluorescence; Tretinoin; Vitamin A

Physiologic concentrations of retinol (1 X 10(-6) M) caused capillary and aortic endothelial cells (EC) to undergo a morphologic change, characterized by a rounder cell body, increased refractility at cell edges, and longer cytoplasmic processes distributed in a bipolar fashion. Computer image analysis of retinoid-treated EC revealed that both retinoic acid and retinol affected cellular area. Twenty-four hours following retinoic acid treatment, EC occupied a greater area than control (P less than 0.03) or retinol-treated EC (P less than 0.02). By Day 7, however, retinoic acid-treated EC occupied equivalent cellular areas as compared to control cells (P = 0.8). In contrast, by Day 7, retinol-treated EC occupied a smaller cellular area than control (P less than 0.002) or retinoic acid-treated EC (P less than 0.001). Proliferation studies revealed that within the first 72 hr of retinol treatment, basal EC growth was inhibited by 33% and the cells exhibited a lowered responsiveness to basic fibroblast growth factor (bFGF). In contrast, EC treated with retinoic acid and pericytes treated with each of the retinoids were not inhibited. The inhibitory effect of the 72 hr retinol treatment was reversible. Following 3 days exposure to retinol, EC given fresh media without retinoid underwent a population doubling in a subsequent 3-day period. However, in the continued presence of retinol, EC were 100% growth-inhibited. After a 3-day pretreatment with retinol, with or without continued retinol treatment, EC were refractile to the mitogenic action of bFGF in a subsequent 3-day period. These results demonstrate that retinol inhibits the basal and growth factor-stimulated growth of EC and causes a significant shape alteration of EC, supporting our hypothesis that vitamin A may be one of the signals that modify the growth and phenotype of EC.

Topics: Adrenal Cortex; Animals; Cattle; Cell Division; Cells, Cultured; Depression, Chemical; Diterpenes; Endothelium, Vascular; Fibroblast Growth Factor 2; Retinyl Esters; Tretinoin; Vitamin A

The effect of three retinoids, 13-cis-retinoic acid, arotinoid ethyl sulfone and retinal acetate, on methylcholanthrene (MCA) induced transformation of 10T1/2 cells was studied. It appears that 13-cis-retinoic acid and arotinoid ethyl sulfone prevent transformation in a direct way at the last stage of carcinogenesis. Retinal acetate, however, requires cell-to-cell contacts to inhibit the transformation of 10T1/2 cells.

Topics: Animals; Cell Transformation, Neoplastic; Cells, Cultured; Diterpenes; Methylcholanthrene; Mice; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

Four retinoids, i.e. retinol (vitamin A), retinoic acid, retinyl acetate and synthetic chalcone carboxylic acid (Ch 55), were examined for their effects on embryonic angiogenesis using 4.5-day chorioallantoic membranes of chick embryo. The effects of these retinoids were compared with that of antibiotic herbimycin A, which was the most powerful inhibitor of the angiogenesis reported previously. The four retinoids strongly inhibited embryonic angiogenesis; the order of inhibitory activity was Ch 55 greater than retinoic acid greater than herbimycin A greater than retinyl acetate based on the dose required for the half-maximal inhibitory effect. The present results suggest that retinoids are effective inhibitors of angiogenesis, and can be applied for the management of certain diseases accompanied by aberrant angiogenesis, particularly that which occurs during progressive growth of solid tumors.

Topics: Animals; Benzoquinones; Chalcone; Chalcones; Chick Embryo; Diterpenes; Dose-Response Relationship, Drug; In Vitro Techniques; Lactams, Macrocyclic; Neovascularization, Pathologic; Quinones; Retinoids; Retinyl Esters; Rifabutin; Tretinoin; Vitamin A

The effect of retinoid administration on the antigen presenting function of mouse dendritic cells (DC) was assessed. Culturing spleen cells with retinoic acid (10(-10)-10(-4) M) had no effect on the numbers of DC separated from these cultures. However, DC isolated from retinoic-acid-treated cultures were less stimulatory than DC from untreated cultures when added to allogeneic lymphocytes in a mixed leucocyte culture. Allogeneic stimulation by DC was also inhibited by pulsing separated DC with retinoic acid (10(-6)-10(-4) M) for 2 h. Pulsing DC with lower doses of retinoic acid (10(-14)-10(-20) M) enhanced this response. DC isolated from animals maintained on VAA-enriched diets had a reduced capacity to stimulate allogeneic lymphocytes. The response of unseparated lymph node cells pulsed with retinoic acid to untreated allogeneic DC was inhibited by 10(-10)-10(-4) M retinoic acid but enhanced by lower doses (10(-14) M). However, the inhibitory effect of retinoids on the function of responding lymphoid populations was abolished on removal of DC from responding cells. The results indicate that immunomodulation by retinoids could occur via an effect on the efficiency of antigen presentation by DC.

Topics: Animals; Cells, Cultured; Dendritic Cells; Diterpenes; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Retinyl Esters; Tretinoin; Vitamin A

NIH 3T3 fibroblasts treated with all-trans-retinoic acid (RA) showed a dramatic decrease in the uptake of [3H]inositol compared to solvent-treated controls. The onset of RA-induced inhibition of [3H]inositol uptake was rapid with a 10-15% decrease occurring after 2-3 h of RA exposure and 60-70% reduction after 16 h of RA treatment. A progressive dose-dependent decrease in inositol uptake was found as the concentration of RA increased from 10(-8) to 10(-5) M and the effect was fully reversible within 48 h after RA removal. The Vmax and Kt for the controls were 10 nmol/2.5 x 10(6) cells/2 h and 51 microM; and for RA-treated cells the values were 4 nmol/2.5 x 10(6) cells/2 h and 52 microM. The decreased [3H]inositol uptake was not due to a change in the affinity (Kt) of the transporter for the inositol but to a decrease in the Vmax. The maximal effect on inositol uptake was dependent on RA treatment of the cells after they reached saturation density or if made quiescent by serum starvation. RA was the most active of the different retinoids examined in the order RA greater than 13-cis-RA = retinyl acetate greater than all-trans-retinol greater than 5,6-dihydroxyretinoic acid methyl ester greater than N-4-hydroxyphenyl retinamide. In contrast to this effect on inositol, the uptake of fucose, mannose, galactose, and glucose was either not affected or enhanced (for mannose and fucose) by RA treatment. RA inhibition of inositol uptake was also observed in 3T3-Swiss and Balb/3T3 cells but not in two virally transformed 3T3 cell lines. Phlorizin, amiloride, and monensin inhibited inositol uptake by 66, 74, and 58%, respectively, and this inhibition was additive when the cells were treated with RA as well as these inhibitors. A decreased incorporation of [3H]inositol into polyphosphoinositides was also observed in RA-treated cells but not to the same extent as for [3H]inositol uptake. In conclusion, RA treatment of 3T3 fibroblasts decreases the uptake of [3H]inositol by up to 70% within 8 to 10 h at near physiological concentrations in a reversible and specific manner.

Topics: Animals; Biological Transport; Carbohydrate Metabolism; Cell Division; Cell Line; Cell Line, Transformed; Diterpenes; Dose-Response Relationship, Drug; Ethylmaleimide; Fenretinide; Fibroblasts; Inositol; Inositol Phosphates; Kinetics; Phosphatidylinositols; Retinyl Esters; Tretinoin; Vitamin A

Pregnant hamsters were given a single oral dose (35 mumol/kg) of all-trans-retinoic acid, 13-cis-retinoic acid, all-trans-4-oxo-retinoic acid, 9-cis-retinal or all-trans-retinyl acetate during the early primitive streak stage of development. The radioactivity associated with the acidic retinoids was distributed to all tissues sampled (including placenta and fetus), with the largest accumulation in the liver and the least accumulation in fat. Radioactivity from 9-cis-retinal or retinyl acetate concentrated in the liver and lung. The all-trans-retinoic acid was oxidized in vivo to all-trans-4-oxo-retinoic acid and isomerized to 13-cis-retinoic acid: 13-cis-retinoic acid was oxidized to 13-cis-4-oxo-retinoic acid and isomerized to all-trans-retinoic acid. No parent 9-cis-retinal or retinyl acetate could be detected in maternal plasma. Plasma concentrations of the parent acidic retinoids reached their maxima within 60 min and then followed exponential decay. Of all the retinoids examined here, 13-cis-retinoic acid showed the largest area under the plasma curve, the slowest clearance and the longest elimination t1/2. Total plasma radioactivity, consisting of unidentified metabolites, remained elevated at 4 days after dosing. Maternal peak circulating concentrations of the parent retinoids, total radioactivity, plasma pharmacokinetic parameters or the total concentrations of residual radioactivity in fetal tissues could not be correlated with the differential teratogenic potencies of these retinoids.

Topics: Animals; Cricetinae; Diterpenes; Female; Mesocricetus; Permeability; Placenta; Pregnancy; Retinaldehyde; Retinoids; Retinyl Esters; Tissue Distribution; Tretinoin; Vitamin A

The inhibition of neoplastic transformation by vitamin A and its natural and synthetic analogues, collectively called retinoids, is accomplished by an as yet unknown mechanism. In a recent report, the morphological transformation of carcinogen-treated C3H 10T1/2 fibroblasts to focus-forming transformed cells was shown to be a postconfluence event induced in density-arrested initiated cells by platelet growth factors in serum and was correlated with the mitogenic response of the preneoplastic cells to these polypeptides. The current study investigates the possibility that the inhibition of neoplastic transformation by retinoids is accomplished by blocking the mitogenic response of initiated cells to these growth factors. The results demonstrate that the stimulation by serum of DNA synthesis and cell division in normal and carcinogen-treated C3H 10T 1/2 fibroblasts after density-dependent growth arrest is inhibited in a dose-dependent manner by retinyl acetate, all-trans retinoic acid, and 4-hydroxyphenyl-retinamide over the same dose range and to the same extent that neoplastic transformation is inhibited by these retinoids. Cellular mitogenic processes sensitive to retinoid inhibition were shown to be induced specifically by platelet growth factors, rather than plasma growth factors, to occur within approximately 2 h of growth factor treatment, and to be common to cell division stimulated in density-arrested normal and initiated cells by highly purified platelet-derived or epidermal growth factor. These data suggest that the inhibition of neoplastic transformation by retinoids is accomplished by blocking the G0 to G1 transition in the mitotic response of initiated cells to platelet growth factors which act as endogenous promoters of transformation.

Topics: Animals; Cell Division; Cells, Cultured; Diterpenes; DNA; DNA Replication; Epidermal Growth Factor; Kinetics; Mice; Mice, Inbred C3H; Platelet-Derived Growth Factor; Retinyl Esters; Tretinoin; Vitamin A

The transfer of retinoic acid, retinyl acetate, and retinyl palmitate between single unilamellar vesicles was studied by resonance energy transfer. The retinoic acid transfers spontaneously between single unilamellar vesicles with a first order rate constant of 9.6 s-1 at 15 degrees C and pH 7.4. At 30 degrees C, the transfer rate was 3.5 times faster than that at 10 degrees C. At pH 7.4, the transfer rate was almost 2 orders of magnitude faster than that observed at pH 1.6. Increasing the concentration of NaCl decreased the retinoic acid transfer rate significantly. Retinyl acetate transfers with a rate constant of 0.15 s-1, but no spontaneous transfer of retinyl palmitate was observed over 60 min. The evidence supports the proposal that retinoic acid and retinyl acetate transfer between single unilamellar vesicles occur via the aqueous phase. In contrast, no spontaneous transfer of retinyl palmitate was observed. However, linear free energy relationships and the thermodynamic parameters for retinyl acetate transfer permit the calculation of rate constant for retinyl palmitate transfer.

Topics: Diterpenes; Energy Transfer; Kinetics; Liposomes; Osmolar Concentration; Phosphatidylcholines; Phosphatidylethanolamines; Retinyl Esters; Spectrometry, Fluorescence; Thermodynamics; Tretinoin; Vitamin A

Vitamin A (retinol) and some of its analogs exhibited varying degrees of inhibition on induced iron and ascorbic acid lipid peroxidation of rat brain mitochondria. Malonyldialdehyde production was used as an index of the extent of in vitro lipid peroxidation. The fat-soluble vitamins retinol, retinol acetate, retinoic acid, retinol palmitate, and retinal at concentrations between 0.1 and 10.0 mmol/L inhibited brain lipid peroxidation. Retinol and retinol acetate were the most effective inhibitors. It is concluded from this study that retinol and its analogs can be considered as potential antioxidant factors, more potent than some of the well-known antioxidants such as alpha-tocopherol and butylated hydroxytoluene.

Topics: Animals; Ascorbic Acid; Brain; Diterpenes; Ferrous Compounds; Free Radicals; Lipid Peroxidation; Male; Malondialdehyde; Mitochondria; Rats; Rats, Inbred Strains; Retinaldehyde; Retinyl Esters; Tretinoin; Vitamin A

Retinoic acid (a possible morphogen), its biological precursor retinol, and certain synthetic derivatives of retinol profoundly change junctional intercellular communication and growth (saturation density) in 10T 1/2 and 3T3 cells and in their transformed counterparts. The changes correlate: growth decreases as the steady-state junctional permeability rises, and growth increases as that permeability falls. Retinoic acid and retinol exert quite different steady-state actions on communication at noncytotoxic concentrations in the normal cells: retinoic acid inhibits communication at 10(-10)-10(-9) M and enhances at 10(-9)-10(-7) M, whereas retinol only enhances (10(-8)-10(-6) M). In v-mos-transformed cells the enhancement is altogether lacking. But regardless of the retinoid or cell type, all growth responses show essentially the same dependence on junctional permeability. This is the expected behavior if the cell-to-cell channels of gap junctions disseminate growth-regulating signals through cell populations.

Topics: Animals; Benzoates; Cell Communication; Cell Division; Cell Line; Cell Line, Transformed; Cell Membrane Permeability; Diterpenes; Dose-Response Relationship, Drug; Intercellular Junctions; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

Retinoic acid and retinyl acetate induce tissue transglutaminase to high levels in cultured SCC-4 keratinocytes, increasing the enzyme specific activity over 50-fold under optimal conditions. Pretreatment of the cells for a day with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3-MC) or benzo[a]pyrene almost completely prevented the induction observed upon subsequent treatment with retinoic acid for 2 days. Similar aromatic compounds that do not induce aryl hydrocarbon hydroxylase (pyrene, dibenzofuran) did not exhibit this suppressive effect. The concentration dependence on TCDD for induction of aryl hydrocarbon hydroxylase was nearly identical to that for its suppression of transglutaminase induction, with half-maximal effects observed at approximately 20 pM in each instance. Similarly, the concentrations of 3-MC giving half-maximal stimulation of the hydroxylase and suppression of the transglutaminase were comparable (0.9 and 0.3 microM, respectively), although this agent was almost five orders of magnitude less potent than TCDD. These observations reveal a loss of cellular sensitivity to vitamin A mediated by the Ah receptor.

Topics: Carcinoma, Squamous Cell; Cell Line; Dioxins; Diterpenes; Enzyme Induction; Humans; Kinetics; Polychlorinated Dibenzodioxins; Polycyclic Compounds; Retinyl Esters; Tetradecanoylphorbol Acetate; Transglutaminases; Tretinoin; Vitamin A

Topics: Animals; Cell Division; Cell Line; Cells, Cultured; Diterpenes; Enzyme Induction; Epidermis; Etretinate; Liver; Male; Mice; Retinoids; Retinyl Esters; Skin; Tetradecanoylphorbol Acetate; Transglutaminases; Tretinoin; Vitamin A

Topics: Acitretin; Animals; Chromatography, High Pressure Liquid; Diterpenes; Etretinate; Rats; Retinyl Esters; Spectrophotometry, Ultraviolet; Tretinoin; Vitamin A

Topics: Adult; Air Pollutants, Occupational; Anemia; Blood Cell Count; Blood Cells; Dark Adaptation; Diterpenes; Drug Industry; Female; Humans; Hypersensitivity, Delayed; Leukocytosis; Middle Aged; Retinyl Esters; Tretinoin; Vitamin A

Retinoids can induce alterations in differentiation and morphogenesis in the hamster cheek pouch. In order to determine the stability of these changes, explants of neonatal pouch were exposed to 6 micrograms/ml of either retinyl acetate (RAc: 1.8 x 10(-5) M) or all-trans retinoic acid (RA: 2.0 x 10(-5) M) for an initial 3 of 7 days, out of a total of 21 days in organ culture. Three days of RAc or RA caused a delay in the differentiation and keratinization of the epithelium at least up to day 7 of culture. Additionally, two out of ten explants exposed to RA showed small downgrowths of epithelium into the stroma at 7 or 14 days. Seven days of exposure to either retinoid led to inhibition of epithelial keratinization, and produced a mucous metaplasia which was still seen at the end of the 21-day culture period. Periodic acid-Schiff (PAS)-positive, diastase-resistant material was present in the metaplastic epithelium, in intercellular, and in some instances, intracellular locations. An excess of either RAc or RA, for 7 days, induced persistent glandlike downgrowths of epithelium, suggesting that a stable alteration in the developmental program of the epithelium may have occurred. Many of these downgrowths possessed a lumen which was lined by cuboidal epithelium and contained PAS-positive, diastase-resistant secretory material. RA appeared more potent than RAc in inhibiting keratinization, in producing a mucous metaplasia, and in initiating glandlike downgrowths. The persistence of glandular downgrowths suggests that retinoids, either directly or indirectly, act in a manner similar to that of an embryonic inductor.

Topics: Animals; Animals, Newborn; Connective Tissue; Cricetinae; Diterpenes; Epithelium; Exocrine Glands; Mesocricetus; Morphogenesis; Mucous Membrane; Mucus; Organ Culture Techniques; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

All-trans-[11-3H]retinyl beta-glucuronide (all-trans-[11-3H]ROG) was synthesized from [3H]retinol by an improved synthetic procedure. After its intraperitoneal injection into rats, ROG is initially found as the predominant labelled component in the serum, but then is distributed to the liver, intestine, kidney and other organs of the body. Esters of vitamin A, which constituted the major metabolite of ROG, were detected in the liver as well as in other tissues. Of the labelled vitamin A esters derived from tritiated ROG in the liver and intestine, about 50% contained 5,6-epoxyretinol, which was characterized by its chromatographic behaviour, formation of an acetyl ester and lack of reactivity with diazomethane. Thus ROG, although converted to retinol in vivo, might also act physiologically in an intact form.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Feces; Intestine, Small; Kidney; Liver; Male; Rats; Rats, Inbred Strains; Retinoids; Retinyl Esters; Tissue Distribution; Tretinoin; Vitamin A

All trans retinoic acid inhibited diferric transferrin reduction by HeLa cells. The NADH diferric transferrin reductase activity of isolated liver plasma membranes was also inhibited by retinoic acid. Retinol and retinyl acetate had very little effect. Transplasma membrane ferricyanide reduction by HeLa cells and NADH ferricyanide reductase of liver plasma membrane was also inhibited by retinoic acid, therefore the inhibition was in the electron transport system and not at the transferrin receptor. Since the transmembrane electron transport has been shown to stimulate cell growth, the growth inhibition by retinoic acid thus may be based on inhibition of the NADH diferric transferrin reductase.

Topics: Animals; Cell Membrane; Diterpenes; HeLa Cells; Humans; Kinetics; Liver; NADH, NADPH Oxidoreductases; Rats; Retinyl Esters; Tretinoin; Vitamin A

This study examines the effects of in-vivo immune regulation by vitamin A acetate (VAA) and 13-cis-retinoic acid (13-CRA) on in-vitro accessory cell function. Mice were fed a control diet, or diet containing VAA or 13-CRA, and monitored by body weight gains and diet consumptions at weekly intervals. At 4, 7 and 12 weeks mice were killed, differential blood counts performed and accessory cells isolated from lymphomedullary tissues. Histology confirmed that the chief feature of the lymphomedullary organs of the VAA-fed animals was an expansion of the splenic marginal zone and the paracortical region of the lymph nodes. There was an increase in the number of accessory cells present, and this included both dendritic cells and macrophages. The accessory cell function of these cells was also increased, as evidenced by both alloproliferative and allocytotoxic responses in vitro. In 13-CRA-fed animals the effects were similar to those seen with VAA, but were less pronounced. We suggest that the primary effects of these compounds on in-vivo immunoregulation could be due to their promotion of accessory cell function.

Topics: Animals; Antigen-Presenting Cells; Cell Count; Cytotoxicity, Immunologic; Dendritic Cells; Diterpenes; Female; Leukocyte Count; Lymph Nodes; Macrophages; Mice; Mice, Inbred Strains; Retinyl Esters; Spleen; Tretinoin; Vitamin A

The effect of vitamin A compounds on the DNA biosynthesis inhibition of murine ascites tumor models such as P388 lymphocytic leukemia, L1210 lymphoid leukemia, sarcoma 180 and Ehrlich ascites carcinoma was found to be concentration- and time-dependent. The results of the experiments carried out in vitro for 4 h measured by the extent of 3H-thymidine incorporation into the DNA of these tumor cells permit us to conclude that (a) at the given concentration and time, the metabolic role of vitamin A compounds influences the regulation of processes leading to DNA biosynthesis inhibition; (b) the effect of vitamin A is uniform irrespective of tumor cells heterogeneity; (c) vitamin A does not affect transport of thymidine, and (d) the dose-dependent increase in the inhibition of these tumor cells by vitamin A is characterized by undifferentiated morphology showing uniformity in the given tumor cell population associated with a total lack of differentiation.

Topics: Animals; Carcinoma, Ehrlich Tumor; Depression, Chemical; Diterpenes; DNA Replication; Leukemia L1210; Leukemia P388; Mice; Mice, Inbred DBA; Neoplasms, Experimental; Retinaldehyde; Retinoids; Retinyl Esters; Sarcoma 180; Tretinoin; Vitamin A

Earlier work from our laboratory had shown that vitamin A-deficient rats had increased levels of fibronectin in their serum. To explain this result, we investigated the mechanism whereby vitamin A deficiency affects the production of fibronectin by liver and hepatocytes, since liver is the known source of plasma fibronectin. By use of cDNA specific for rat liver fibronectin, we showed that livers of vitamin A-deficient rats had a 2-4-fold increase in the level of fibronectin mRNA and also a higher transcription rate. Rate of synthesis and secretion of fibronectin was found to be increased 2-fold in primary cultures of hepatocytes of deficient animals. Exogenous addition of retinyl acetate or retinoic acid to the media reversed this increase to control levels. The increase was paralleled by an increase in fibronectin mRNA, also reversed by exogenous retinoic acid. At least 12 h were needed for this reversal to take place. Thus, vitamin A appears to regulate the synthesis of fibronectin through its action on fibronectin mRNA transcription. This represents the first reported observation of an action of vitamin A at the genomic level on the synthesis of a specific protein in liver.

Topics: Animals; Cells, Cultured; Diterpenes; Fibronectins; Gene Expression Regulation; Kinetics; Liver; Male; Rats; Retinyl Esters; RNA, Messenger; Transcription, Genetic; Tretinoin; Vitamin A; Vitamin A Deficiency

We have examined RNA synthesis by nuclei isolated from testes of rats of varying vitamin A status. Nuclei from retinol-deficient animals showed substantially decreased RNA synthesis by polymerase II when compared to nuclei from normal animals. Within 4 hours after oral administration of retinyl acetate (as the source of retinol) to deficient animals, RNA synthesis by polymerase II had significantly increased. Administration of retinoic acid had a similar but lesser effect. Nucleoside analysis after alkaline hydrolysis of the RNA synthesized by the endogenous polymerase II suggested that the increased activity was due to a greater number of actively transcribing polymerase II molecules on the DNA. Further, when the template capacity of testicular chromatin isolated from deficient and retinyl acetate refed animals was compared, the number of sites recognized by E. coli RNA polymerase was increased twofold after retinyl acetate administration. We conclude that these retinol-induced changes in transcription are due at least in part to changes in chromatin structure.

Topics: Animals; Chromatin; Diterpenes; Male; Rats; Retinyl Esters; RNA; RNA Polymerase II; Testis; Transcription, Genetic; Tretinoin; Vitamin A; Vitamin A Deficiency

Retinoic acid potentiated the increases in ornithine decarboxylase (L-ornithine carboxy-lyase [EC 4.1.1.17]) activity, [3H]difluoromethylornithine binding to ornithine decarboxylase, intracellular levels of polyamines and DNA synthesis in guinea pig lymphocytes stimulated with phytohemagglutinin. The stimulatory effect on the ornithine decarboxylase induction was dependent on the dose of retinoic acid and on the time of addition of the drug. Retinoic acid has to be added not later than 2 h after phytohemagglutinin to elicit the potentiation. Retinyl acetate also potentiated ornithine decarboxylase induction caused by phytohemagglutinin. Both of these retinoids augmented ornithine decarboxylase induction caused by phorbol 12-myristate 13-acetate. The half-life of ornithine decarboxylase activity estimated after addition of actinomycin D was longer in cells treated with phytohemagglutinin or phorbol 12-myristate 13-acetate together with retinoic acid than in cells treated with the mitogen alone. The half-life after addition of cycloheximide was not affected by retinoic acid. These results suggest that the retinoids are stimulators rather than inhibitors of ornithine decarboxylase induction caused by phytohemagglutinin or phorbol 12-myristate 13-acetate in guinea pig lymphocytes and that retinoic acid potentiates the enzyme activity at the transcriptional or posttranscriptional, but not at the post-translational stage.

Topics: Animals; Diterpenes; DNA; Drug Synergism; Eflornithine; Enzyme Induction; Guinea Pigs; In Vitro Techniques; Leucine; Lymphocytes; Ornithine; Ornithine Decarboxylase; Phorbols; Phytohemagglutinins; Polyamines; Retinyl Esters; Tetradecanoylphorbol Acetate; Time Factors; Tretinoin; Vitamin A

The placental transfer of 3H-retinoic acid in vitamin A deprived and vitamin A supplemented pregnant female rats was studied on 20th day of gestation and compared with 3H-retinyl acetate. Radiolabelled compounds were administered to pregnant mothers orally in groundnut oil six hours before sacrifice. The distribution of radioactivity of the two compounds was studied in maternal intestine, liver and plasma and fetal brain, heart liver lung and placenta. The transfer of 3H-retinoic acid across placenta was restricted as compared to that of 3H-retinyl acetate which may explain the reason why retinoic acid does not support fetal growth.

Topics: Animals; Biological Transport, Active; Diterpenes; Female; Fetus; Maternal-Fetal Exchange; Placenta; Pregnancy; Rats; Rats, Inbred Strains; Retinyl Esters; Tissue Distribution; Tretinoin; Vitamin A

The vitamin A analogs retinoic acid and retinol caused a significant increase in concanavalin A-induced agglutination of human erythrocytes, while its esters, retinyl acetate and retinyl palmitate, were found to be ineffective. The effect of membrane labilizers and stabilizers on the enhancement of agglutination as well as the properties of the model system employed showed that the action of vitamin A is due to a direct action on cell membrane and is not mediated by the release of lysosomal proteases into the medium, a hypothesis proposed by earlier workers.

Topics: Concanavalin A; Diterpenes; Erythrocytes; Hemagglutination; Humans; Retinyl Esters; Tretinoin; Vitamin A

All-trans-[11-3H]retinyl acetate was injected directly into the testes of young rats and testicular and liver metabolites were analyzed by HPLC at 6, 24 and 72 h post injection. All-trans-retinyl acetate was hydrolyzed to retinol and further metabolized to polar compounds and a trace of retinoic acid, or reesterified to various retinyl esters including retinyl palmitate and retinyl stearate. Thus, retinyl ester hydrolyzing and esterifying enzymes are present in the testes of young rats. Eleven, twelve and ten radioactive peaks were observed at 6, 24 and 72 h, respectively. The amount of radioactivity in retinyl palmitate and retinyl stearate increased with time and reached 24 and 4%, respectively, by 72 h. Although retinol predominated, retinyl palmitate was the major esterified form in testis. The amount of radioactivity in retinol and retinyl acetate decreased with time and increased in unidentified metabolites and retinyl esters. An insignificant amount of radioactivity was found in liver. We conclude from these results that some vitamin A is stored/accumulated in the testes as retinyl esters in order to support the process of spermatogenesis and other physiological functions and that the retinol esterifying enzyme is quite active in the testes of young rats.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Injections; Liver; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Testis; Time Factors; Tretinoin; Vitamin A

The influence of all-trans- and 13-cys-methylretinoate on antibacterial and antiviral immunity was studied in experiments on noninbred C57Bl/6 and (CBA X C57Bl/6) F1 mice. All-trans-methylretinoate was shown to stimulate the production of antibodies to E. coli antigens, with the effect being dose-dependent. At the same time both compounds inhibited the production of inhibitors, interferon and antibodies to influenza virus.

Topics: Animals; Antibodies, Bacterial; Antibodies, Viral; Antibody Formation; Antiviral Agents; Diterpenes; Escherichia coli; Female; Interferons; Male; Mice; Orthomyxoviridae; Retinyl Esters; Tretinoin; Vitamin A

Growth of SCC-13 squamous carcinoma cultures in the presence of retinoids considerably reduced the expression of two differentiation markers, the cellular capability to form cross-linked envelopes, and the enzyme transglutaminase required for cross-linking. A limited survey of retinoids showed that all-trans retinoic acid, 13-cis retinoic acid, and arotinoid Ro 13-6298 were highly effective in the absence of hydrocortisone and were only slightly antagonized by its presence in the medium. In contrast, retinyl acetate, retinol, and retinol bound to its plasma binding protein were quite active in the absence of hydrocortisone but were essentially inactive in its presence. Dexamethasone was also highly effective in antagonizing the suppressive action of retinyl acetate on envelope formation, while the corticosteroid antagonists cortexolone and progesterone were inactive. These results suggest that there are separate pathways, which are differentially regulated by hydrocortisone, for either the metabolism or action of retinol and retinoic acid in SCC-13 cells.

Topics: Acyltransferases; Carcinoma, Squamous Cell; Cell Line; Cell Membrane; Diterpenes; Humans; Hydrocortisone; Kinetics; Retinoids; Retinyl Esters; Structure-Activity Relationship; Transglutaminases; Tretinoin; Vitamin A

Retinol and retinoic acid were effective activators of oxygen consumption by human polymorphonuclear leucocytes (PMN) in micromolar concentrations. In contrast, retinyl acetate was ineffective as an activator. Retinol caused activation only after a lag time, the length of which depended on retinol concentration. Oxygen consumption was due to superoxide production by PMN. Superoxide production was observed as superoxide dismutase-inhibitable cytochrome c reduction. Previously, retinoids have been reported to inhibit PMN activation by phorbol myristate acetate, a tumour promoter. This retinoid-induced inhibition of PMN activation has been suggested to be a mechanism by which retinoids may protect against carcinogenesis in animals. However, the retinoid concentrations at which PMN inhibition was reported were much higher than those found to cause activation in this study. We found that retinoic acid slightly inhibited phorbol myristate acetate-activated superoxide production, but only at concentrations that caused activation. In contrast, activation by formyl-Met-Leu-Phe was effectively inhibited at a retinoic acid concentration that did not cause activation by itself.

Topics: Diterpenes; Ethylmaleimide; Humans; Neutrophils; Oxygen Consumption; Retinoids; Retinyl Esters; Superoxide Dismutase; Superoxides; Time Factors; Tretinoin; Vitamin A

Retinol esterification by microsomal acyl coenzyme A:retinol acyltransferase was quantified in rat mammary tumor and liver tissue. Acyltransferase activity in the livers of mammary tumor-bearing rats was 40% of that in normal animals. In response to daily oral doses of 2 mg retinyl acetate for 18-19 days, activity increased 2.8-fold in transplanted rat mammary tumors, 4.1-fold in the livers of tumor-bearing rats, and 1.5-fold in the livers of normal rats. The in vitro esterification of retinol was competitively inhibited by all-trans-N-(4-hydroxyphenyl) retinamide (Ki = 154 microM).

Topics: Acyltransferases; Animals; Cell Line; Diterpenes; Female; Fenretinide; Kinetics; Liver; Mammary Neoplasms, Experimental; Microsomes, Liver; Rats; Rats, Inbred F344; Retinol O-Fatty-Acyltransferase; Retinyl Esters; Tretinoin; Vitamin A

As part of the preclinical drug safety evaluation of the cancer chemopreventive agent N-(4-hydroxyphenyl)retinamide (HPR) in vitro and in vivo tests were conducted to assess its genotoxic activity. Negative findings from HPR testing were demonstrated in the Ames Salmonella/microsomal activation test, the L5178Y mouse lymphoma assay, and a rat bone marrow cytogenetics study. These data imply that HPR lacks the ability to induce point mutations or chromosomal aberrations, and is therefore not genotoxic. Limited testing of retinyl acetate in the Ames test, the L5178Y mouse lymphoma assay, and the primary rat hepatocyte/DNA repair assay yielded consistently negative results. These findings and previously published results concerning retinoid genotoxicity are discussed.

Topics: Animals; Antineoplastic Agents; Bone Marrow Cells; Chromosome Aberrations; Cricetinae; Cytogenetics; Diterpenes; Fenretinide; Leukemia L5178; Male; Mesocricetus; Mice; Mitosis; Mutagenicity Tests; Rats; Retinoids; Retinyl Esters; Salmonella typhimurium; Tretinoin; Vitamin A

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Female; Fenretinide; Liver; Mice; Rats; Rats, Inbred Strains; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

Several embryonal carcinoma (EC) cell lines were tested in culture for their ability to metabolize all-trans-[3H]retinol, all-trans-[3H]retinyl acetate, and all-trans-[3H]retinoic acid. There was little, if any, metabolism of all-trans-retinol to more polar compounds; we failed to detect conversion to acidic retinoids by reverse-phase high performance liquid chromatography and derivatization. We also did not observe [3H]retinoic acid when EC cells were incubated with [3H]retinyl acetate. Unlike the other retinoids, all-trans-[3H]retinoic acid, even at micromolar levels, was almost totally modified by cells from several EC lines within 24 h. Most of the labeled products were secreted into the medium. Some EC lines metabolized retinoic acid constitutively, whereas others had an inducible enzyme system. A differentiation-defective line, which contains little or no cellular retinoic acid-binding protein activity, metabolized retinoic acid poorly, even after exposure to inducers. At least eight retinoic acid metabolites were generated; many contain hydroxyl residues. Our data lead us to propose that retinol does not induce differentiation of EC cells in vitro via conversion to retinoic acid. Also, the relatively rapid metabolism of retinoic acid by EC cells suggests either that the induction of differentiation need involve only a transient exposure to this retinoid or that one or more of the retinoic acid metabolites can also promote differentiation.

Topics: Animals; Cell Differentiation; Cell Line; Chromatography, High Pressure Liquid; Diterpenes; Isomerism; Neoplasms, Experimental; Retinoids; Retinyl Esters; Teratoma; Tretinoin; Vitamin A

Invasion of chick chorioallantoic membrane (CAM) organ cultures by rat 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 (3Y1/12-10 cells) was inhibited by several retinoids tested. The anti-invasive activity of the retinoids was dependent on retinoid concentration and continuous (4 d) exposure of the CAM. The 50% retinoid dose (dose effective in achieving a response in half of the organ cultures) that inhibited invasion was 0.85 micrograms/ml of retinol palmitate, 0.39 micrograms/ml of retinoic acid, or 0.16 micrograms/ml of retinol acetate. This dose was of the same order of magnitude as that which induced CAM differentiation, and was three- to fourfold less than the dose that caused cytotoxic damage of CAM. In addition, the retinoids inhibited 3Y1/12-10 cell growth by approximately 40% at levels over 10-fold higher than those needed for anti-invasion activity. The findings suggest that the anti-invasive activity of retinoids was at least partly due to direct induction of cell differentiation of the CAM host tissue.

Topics: Adenoviruses, Human; Allantois; Animals; Cell Differentiation; Cell Division; Cell Transformation, Neoplastic; Cell Transformation, Viral; Chick Embryo; Chorion; Diterpenes; Extraembryonic Membranes; Neoplasm Invasiveness; Organ Culture Techniques; Rats; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

The kinetics and metabolism of physiological doses of all-trans-retinoic acid were examined in blood and small intestinal mucosa of vitamin A-depleted rats. A major portion of intrajugularly injected retinoic acid is rapidly (within 2 min) sequestered by tissues; subsequently 13-cis-retinoic acid and polar metabolites are released into circulation. All-trans-retinoic acid appears in small intestinal epithelium within 2 min after dosing and is the major radioactive compound there for at least 2 h. Retinoyl glucuronide and 13-cis-retinoic acid are early metabolites of all-trans-retinoic acid in the small intestine of bile duct-cannulated rats. Retinoyl glucuronide, the major metabolite of retinoic acid intestinal epithelium, in contrast to other polar metabolites, was not detected in circulation. An examination of [3H]retinyl acetate metabolites under steady state conditions in vitamin A-repleted rats demonstrates the occurrence of all-trans-retinoic acid and 13-cis-retinoic acid in circulation and in intestinal epithelium, in a pattern similar to that found after injection of retinoic acid into vitamin A-depleted rats. Our data establish that all-trans-retinoic acid, 13-cis-retinoic acid, and retinoyl glucuronide are physiological metabolites of vitamin A in target tissues, and therefore are important candidates as mediators of the biological effect of the vitamin.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Intestinal Mucosa; Intestine, Small; Isomerism; Kinetics; Male; Rats; Rats, Inbred Strains; Retinoids; Retinyl Esters; Structure-Activity Relationship; Tretinoin; Tritium; Vitamin A; Vitamin A Deficiency

Low concentrations of retinol (10 nM-10 microM) and dexamethasone (0.1 nM-1.0 microM) elevated activity of alkaline phosphatase (E.C. 3.1.3.1) in bovine endothelial cells in culture. The effect was apparent after 48 hr of growth in the presence of either of the two compounds, prior to any growth stimulatory effects. A synergistic stimulation of alkaline phosphatase was achieved in the presence of both retinol and dexamethasone implying different mechanisms of induction. Retinoic acid and retinyl acetate also elevated alkaline phosphatase but the retinol analogue reduced in the side chain (perhydroretinol) was inactive. The ability of steroids to elevate alkaline phosphatase activity was associated with the structure commonly required for glucocorticoid activity; however, competitors for the steroid receptor binding failed to prevent the elevation by dexamethasone or the synergism in the presence of retinol and dexamethasone.

Topics: Alkaline Phosphatase; Animals; Aorta; Cattle; Dexamethasone; Diterpenes; Dose-Response Relationship, Drug; Drug Synergism; Endothelium; Glucocorticoids; Retinoids; Retinyl Esters; Tretinoin; Triamcinolone Acetonide; Vitamin A

The influence of retinyl acetate, retinoic acid and its esterified cis- and trans-derivatives, retinoids C15 and C20 on erythrocytes, liver macrophages and white pulp of the spleen was studied in the experiments on mice of different strains. It was found that administration of these compounds leads to the damage of the blood cells, increase in the number of liver macrophages and the share of white pulp in the spleen and stimulation of the local response to tuberculin. The interdependence of changes in the blood and adjuvant is suggested.

Topics: Adjuvants, Immunologic; Animals; Diterpenes; Erythrocytes; Female; Liver; Macrophages; Male; Mice; Mice, Inbred CBA; Retinoids; Retinyl Esters; Spleen; Tretinoin; Vitamin A

Topics: Acitretin; Chromatography, High Pressure Liquid; Diterpenes; Etretinate; Humans; Retinoids; Retinyl Esters; Tretinoin; Vitamin A

Feeding of retinyl acetate (0.2 mM) or N-(4-hydroxyphenyl) retinamide (4-HPR) (1.0 mM) for 27 weeks to female BD2F1 mice previously treated with a series of gastric intubations of 7,12-dimethylbenzanthracene (DMBA), did not significantly affect the incidence of mammary tumors. In the retinyl acetate study, 75 retinyl acetate fed mice developed 31 mammary adenocarcinomas and 19 mammary adenoacanthomas (50 total mammary tumors) while 75 control mice developed 22 mammary adenocarcinomas and 20 mammary adenoacanthomas (42 total mammary tumors). In the 4-HPR study, 74 4-HPR fed mice developed 45 mammary adenocarcinomas and 41 mammary adenoacanthomas (86 total mammary tumors) while 74 control mice developed 29 mammary adenocarcinomas and 44 mammary adenoacanthomas (73 total mammary tumors). Retinoid treatments did not significantly affect body weight gains or mortality rates. These results provide evidence that carcinogen induced mouse mammary gland tumorigenesis in vivo is not influenced by hyperalimentation of dietary retinoids.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Anaplasia; Animals; Diet; Diterpenes; Female; Fenretinide; Mammary Glands, Animal; Mammary Neoplasms, Experimental; Mice; Mice, Inbred Strains; Retinoids; Retinyl Esters; Species Specificity; Tretinoin; Vitamin A

Female Sprague-Dawley rats were treated at 50 and 57 days of age with 2.5 mg per 100 g body weight of N-methyl-N-nitrosourea (MNU). At 60 days of age, the animals were divided into eight groups (40 rats/group) and treated as follows: (a) controls; (b) immune stimulation (IS); (c) hormone inhibition (HI); (d) HI + IS; (e) retinyl acetate feeding (RA); (f) RA + IS; (g) RA + HI; and (h) RA + HI + IS. IS treatment was accomplished by three i.p. injections (at 1, 3, and 5 weeks after carcinogen treatment) of a mixture of cell particulate preparations from pooled MNU-induced rat mammary carcinomas and Freund's (complete) adjuvant. HI treatment consisted of daily s.c. injections of tamoxifen (12.5 to 25.0 micrograms/100 g body weight) and CB-154 (200 to 400 micrograms/100 g body weight), and RA treatment consisted of daily feeding of retinyl acetate (1.0 mM). Both RA alone and HI alone significantly (p less than 0.01 to 0.001) reduced mammary carcinoma incidence; HI treatment was significantly (p less than 0.01) more effective than RA treatment. The combination of RA + HI was significantly (p less than 0.01) superior to either treatment alone; RA + HI treatment virtually completely blocked the development of mammary carcinomas at termination of study (a total of only 2 mammary carcinomas was observed in the RA + HI groups of rats at 1 year after carcinogen treatment). IS treatments did not significantly influence mammary carcinoma incidence, either alone or in combination with RA and/or HI. Female Sprague-Dawley rats given MNU and subsequently treated daily for 4 weeks with the prolactin secretion-stimulating drug haloperidol (0.05 mg/100 g body weight) responded with a significant (p less than 0.001) increase in mammary carcinoma development when compared with control rats. RA treatment of haloperidol-treated rats significantly (p less than 0.001) blocked the stimulatory effect of haloperidol on mammary carcinoma development. The addition of insulin (5.0 micrograms/ml) to the culture media of 2-day organ cultures of MNU-induced rat mammary carcinomas resulted in a significant (p less than 0.05) stimulation of [3H] thymidine incorporation into DNA of the cultured cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Animals; Diterpenes; DNA Replication; Female; Freund's Adjuvant; Haloperidol; Immunization; Insulin; Mammary Neoplasms, Experimental; Methylnitrosourea; Organ Culture Techniques; Prolactin; Rats; Rats, Inbred Strains; Retinyl Esters; Tretinoin; Vitamin A

All-trans [11-3H]4,4- difluororetinyl acetate was synthesized by treating methyl all-trans [11-3H]4- oxoretinoate with diethylaminosulfurtrifluoride , followed by reduction and acetylation of the product. After oral administration of the radioactive difluoro analog in oil to rats, difluororetinol , difluororetinyl palmitate and related esters, 4- oxoretinol , 4- oxoretinoic acid and polar conjugated derivatives were identified in the intestine, liver, kidney and/or blood. The major metabolic products were difluororetinyl palmitate and related esters, which were stored in the liver. The presence of the difluoro analog in liver oil from treated rats was confirmed by 19F-NMR spectroscopy. Neither retinol nor retinyl esters were detected as products of the metabolism of the difluoro analog. Nonetheless, all-trans difluororetinyl acetate showed 26 +/- 12% of the biological activity of all-trans retinyl acetate in the rat growth assay. Presumably, the difluoro analog is active per se in growth rather than by conversion to retinol or to one of its known growth-promoting metabolites. In general, however, the difluoro analog was metabolized in a manner very similar to vitamin A. The vitamin A moiety of administered difluororetinyl acetate and retinyl acetate was poorly stored (1.8-3.3%) in the liver of vitamin A-depleted rats, confirming and extending past reports that the liver storage mechanism is severely impaired when initial liver stores are very low.

Topics: Animals; Biological Assay; Body Weight; Diterpenes; Feces; Kinetics; Liver; Magnetic Resonance Spectroscopy; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Tissue Distribution; Tretinoin; Vitamin A

Epidermal hyaluronic acid synthesis in pig skin is increased by all-trans-retinoic acid, all-trans-retinyl acetate, 13-cis-retinoic acid and etretinate.

Topics: Animals; Culture Techniques; Diterpenes; Epidermis; Etretinate; Hyaluronic Acid; Isomerism; Isotretinoin; Retinoids; Retinyl Esters; Swine; Tretinoin; Vitamin A

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Testis; Tretinoin; Vitamin A

These experiments describe further investigations into the effects of vitamin A on regenerating limbs. The effects of different retinoids, the time of administration, concentration of vitamin A and histological, autoradiographic and histochemical studies are reported. The most obvious result of vitamin A treatment is to cause proximal elements to regenerate from distal amputation levels, that is to cause serial reduplication of pattern in the proximodistal axis. Retinoic acid was the most potent of the analogues tested and longer times of administration or higher concentrations cause a greater amount of serial reduplication. Various tissue changes have been found which include the inhibition of cell division, loss of cartilage metachromasia, changes in the mucous-secreting properties of the epidermis and an increased packing in the blastemal cells. The significance of these cellular effects in relation to the pattern-formation changes is discussed.

Topics: Ambystoma mexicanum; Animals; Connective Tissue; Diterpenes; Dose-Response Relationship, Drug; Forelimb; Mitotic Index; Morphogenesis; Regeneration; Retinyl Esters; Time Factors; Tretinoin; Vitamin A

We treated experimental corneal epithelial wounds in rabbits with topical retinoids. Treatment with 0.1% all-trans-retinoic acid three times per day resulted in a 21% increase in the healing rate compared to the control eyes. Treatment five times a day resulted in a 35% increase in healing rate. Treatment with topical retinoic acid also promoted corneal deturgescence. Retinyl palmitate, retinyl acetate, retinol, and 13-cis-retinoic acid had no effect on corneal wound healing. These data suggested that topically applied all-trans-retinoic acid may be effective in promoting corneal healing after surgery and in the treatment of persistent and recurring corneal epithelial defects.

Topics: Administration, Topical; Animals; Cornea; Corneal Injuries; Diterpenes; Rabbits; Retinyl Esters; Tretinoin; Vitamin A; Wound Healing

The effects of retinyl acetate and all-trans-retinoic acid on the growth rate, saturation density, and cytoplasmic underlapping of normal and carcinogen-initiated C3H/1OT1/2 cells were examined. Retinyl acetate (a) decreased the saturation density by as much as 45%, (b) had no effect on the growth rate, (c) reduced cytoplasmic underlapping of adjacent cells by 55 to 85%, and (d) inhibited neoplastic transformation by methylcholanthrene. The effects were dose dependent and not significantly affected by the serum concentrations over the range of 2.5 to 10%. In contrast, all-trans-retinoic acid (a) decreased the saturation density as effectively as retinyl acetate, but only in medium containing 10% serum; (b) significantly reduced the growth rate of cells at low density, especially at low serum concentrations; (c) had no effect upon cytoplasmic underlapping; and (d) enhanced transformation at nontoxic concentrations in medium containing 5% serum but had no effect in 10% serum. We conclude that the effects of retinoids on the growth rate and saturation density of cells in culture may not be relevant to their inhibition of neoplastic transformation. Rather, we interpret the results of our experiments on cytoplasmic underlapping as an indication that retinoids inhibit transformation by stabilizing and/or enhancing cell surface receptors involved in cell-cell contact-dependent formation of a stable monolayer.

Topics: Animals; Cell Cycle; Cell Transformation, Neoplastic; Cells, Cultured; Diterpenes; Embryo, Mammalian; Kinetics; Methylcholanthrene; Mice; Mice, Inbred C3H; Retinyl Esters; Tretinoin; Vitamin A

A study has been made of the effects of retinoic acid, retinal, retinol, retinyl palmitate and retinyl acetate on HeLa cell viability. The results obtained show that (i) these cells seem to be more resistant to vitamin A than other cell cultures; (ii) the various vitamin A compounds differ in their inhibitory action on HeLa cells; (iii) the effects of retinoic acid, retinal, retinol and retinyl acetate are cytotoxic, those of retinyl palmitate are always cytolytic.

Topics: Cell Survival; Diterpenes; HeLa Cells; Humans; Retinaldehyde; Retinyl Esters; Tretinoin; Vitamin A

A study was conducted on the incorporation of [11-3H]retinyl acetate into various retinyl esters in liver tissues of rats either vitamin A-sufficient, vitamin A-deficient or vitamin A-deficient and maintained on retinoic acid. Further, the metabolism of [11-3H]retinyl acetate to polar metabolites in liver tissues of these three groups of animals was investigated. Retinol metabolites were analyzed by high-performance liquid chromatography. In vitamin A-sufficient rat liver, the incorporation of radioactivity into retinyl palmitate and stearate was observed at 0.25 h after the injection of the label. The label was further detected in retinyl laurate, myristate, palmitoleate, linoleate, pentadecanoate and heptadecanoate 3 h after the injection. The specific radioactivities (dpm/nmol) of all retinyl esters increased with time. However, the rate of increase in the specific radioactivity of retinyl laurate was found to be significantly higher (66-fold) than that of retinyl palmitate 24 h after the injection of the label. 7 days after the injection of the label, the specific radioactivity between different retinyl esters were found to be similar, indicating that newly dosed labelled vitamin A had now mixed uniformly with the endogenous pool of vitamin A in the liver. The esterification of labelled retinol was not detected in liver tissues of vitamin A-deficient or retinoic acid-supplemented rats at any of the time point studied. Among the polar metabolites analyzed, the formation of [3H]retinoic acid from [3H]retinyl acetate was found only in vitamin A-deficient rat liver 24 h after the injection of the label. A new polar metabolite of retinol (RM) was detected in liver of the three groups of animals. The formation of 3H-labelled metabolite RM from [3H]retinyl acetate was not detected until 7 days after the injection of the label in the vitamin A-sufficient rat liver, suggesting that metabolite RM could be derived from a more stable pool of vitamin A.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Female; Kinetics; Liver; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Tretinoin; Tritium; Vitamin A; Vitamin A Deficiency

Cultured keratinocytes afford an excellent opportunity to study the influence of retinoids on the behavior of a stratified squamous epithelium and the interaction of keratinocytes with substrate. We have found that all-trans-retinoic acid retards the formation of colonies, dose not influence attachment, and causes increased shedding of cells from the cultures. Retinoids do not influence the relative abundance of the keratin polypeptides. Our observations are on human neonatal foreskin-derived keratinocytes grown in Dulbecco's modified Eagle medium containing 20% fetal bovine serum. Because fetal bovine serum contains vitamin A, our findings represent differences between low and high levels of vitamin A.

Topics: Cell Adhesion; Cell Division; Cells, Cultured; Diterpenes; Etretinate; Humans; Isomerism; Isotretinoin; Keratins; Male; Penis; Retinyl Esters; Skin; Tretinoin; Vitamin A

Topics: Animals; Diterpenes; DNA; Genes; Intestinal Mucosa; Liver; Male; Poly A; Protein Biosynthesis; Rats; Rats, Inbred Strains; Retinyl Esters; RNA; RNA, Messenger; Testis; Transcription, Genetic; Tretinoin; Vitamin A; Vitamin A Deficiency

Topics: Acitretin; Chromatography, High Pressure Liquid; Diterpenes; Etretinate; Humans; Retinyl Esters; Tretinoin; Vitamin A

Vitamin A and its analogues (retinoids) affect normal and malignant hematopoietic cells. We examined the effect of retinoids on the clonal growth in vitro of myeloid leukemia cells. Retinoic acid inhibited the clonal growth of the KG-1, acute myeloblastic leukemia, and the HL-60, acute promyelocytic leukemia, human cell lines. The KG-1 cells were extremely sensitive to retinoic acid, with 50% of the colonies inhibited by 2.4-nM concentrations of the drug. A 50% growth inhibition of HL-60 was achieved by 25 nM retinoic acid. Complete inhibition of growth of both leukemia cell lines was seen with 1 microM retinoic acid. Exposure of KG-1 cells to retinoic acid for only 3-5 d was sufficient to inhibit all clonal growth. The all-trans and 13-cis forms of retinoic acid were equally effective in inhibiting proliferation. Retinal, retinyl acetate, and retinol (vitamin A) were less potent inhibitors. Clonal growth of the human K562 and mouse M-1 myeloid leukemic cell lines was not affected by 10 microM retinoic acid. Retinoic acid also inhibited the clonal growth of leukemia cells from five of seven patients with acute myeloid leukemia. Retinoic acid at concentrations of 5 nM to 0.3 microM inhibited 50% clonal growth, and 1 microM retinoic acid inhibited 64-98% of the leukemic colonies. The inhibition of clonal growth of KG-1 and HL-60 cell lines and of leukemic cells from two patients was not associated with the presence of a specific cytoplasmic retinoic acid-binding protein. Our study suggests that retinoic acid may prove to be effective in the treatment of human myeloid leukemia.

Topics: Animals; Carrier Proteins; Cell Line; Cell Transformation, Neoplastic; Clone Cells; Cytosol; Diterpenes; Dose-Response Relationship, Drug; Humans; Leukemia, Myeloid, Acute; Mice; Receptors, Retinoic Acid; Retinyl Esters; Tretinoin; Vitamin A

Rats on a normal diet were administered physiological doses of [3H]retinyl acetate or [3H]retinol orally for 5 days to label endogenous retinoid pools. The kidney retinoids were extracted and separated by DEAE-Sephadex into neutral and acidic fractions. All-trans-retinoic acid and 5,6-epoxyretinoic acid were isolated and unequivocally identified by chromatographic analysis, chemical derivatization, and mass spectroscopy. The identities of retinol and retinyl palmitate were verified by high performance liquid chromatography and reactivity with trifluoroacetic acid. Control experiments showed that retinoid epoxidation truly occurred in vivo. The specific radioactivities of the recovered acidic retinol metabolites were similar to those of the recovered neutral retinoids. Thus, retinoic acid and its metabolite 5,6-epoxyretinoic acid are endogenous rat kidney retinoids which are in the pathway of retinol metabolism under physiological conditions. The concentrations of retinyl palmitate (8.7 microM), retinol (4.6 microM), all trans-retinoic acid (1.3 microM) and 5,6-epoxyretinoic acid (0.25 microM) measured indicate that acidic retinoids are comparatively significant vitamin A metabolites in kidney.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Kidney; Male; Mass Spectrometry; Rats; Rats, Inbred Strains; Retinyl Esters; Tretinoin; Vitamin A

The effects of feeding various levels and combinations of retinyl acetate, beta-carotene, or retinoic acid on skin wound healing in rats was investigated. Weanling male Sprague-Dawley rats were fed a vitamin A-free diet for 2 weeks to produce marginal vitamin A status. After a paravertebral incision was made and closed with suture, one of several diets were fed for either 5 or 14 days. Surgery and recovery did not reduce liver vitamin A nor serum retinol levels compared to nonoperated pair-fed controls. Supplemental retinyl acetate feeding at five times the NRC-suggested allowance resulted in a mild, but significantly increased postmortem wound tensile strength after 5 days compared to rats fed the suggested allowance. Although a low level of retinoic acid in the diet (1.3 microgram/g diet) depressed wound strength at 5 days, a higher level (5.2 microgram/g) increased the strength 57% above controls. Still higher levels (49.1 microgram/g) did not further increase the tensile strength of the wound. beta-Carotene fed the requirement level for 5 days (with compensation made for utilization as one-sixth that of retinol) doubled wound strength compared to rats fed the requirements as retinyl acetate. Vitamin A feeding did not enhance wound strength after 14 days of feeding. It is concluded that supplemental retinyl acetate, beta-carotene, or in some cases all-trans-retinoic acid can be effective in enhancing wound strength, 5 days, but not 14 days after surgery, of young male rats with marginal vitamin A status.

Topics: Administration, Oral; Animals; beta Carotene; Carotenoids; Diterpenes; Dose-Response Relationship, Drug; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Skin; Time Factors; Tretinoin; Vitamin A; Wound Healing

Topics: Diterpenes; Lasers; Photolysis; Retinyl Esters; Spectrophotometry; Tretinoin; Vitamin A

Using mitomycin C treated 3T3-Swiss fibroblasts as feeder cells, human keratinocytes derived from infant foreskins were subcultured in the presence of trans-retinoic acid (RA) and other retinoids. At 1 microgram/ml (3 x 10(-6) M) and higher RA concentrations plating efficiency was markedly reduced. Addition of retinoids to 1 microgram/ml after colonies were established produced no change in the rate of cell production, but caused differentiated cells to be sloughed earlier than in control cultures. Electron microscopy showed wider extra cellular spaces the contained numerous villi, increased numbers of microvilli at the surfaces of the outermost cells, and decreased number of cell layers all of which were consistent with the observed desquamatory effects of RA. Retinoic acid also extended the time during which cell population increased so that RA treated cultures produced more cells than control cultures over their respective lifetimes. Keratin polypeptides represented a smaller percentage of the total solubilizable protein and more keratin was present as acid soluble prekeratin in postconfluent RA treated cultures. This may be a consequence of early desquamation rather than a decrease in keratin synthesis. No unusual proteins were visible in RA treated cultures by simple sodium dodecylsulfate electrophoresis, nor was there increase in specific activities of three lysosomal enzymes.

Topics: Animals; Cell Differentiation; Cell Division; Cell Line; Cell Membrane; Cells, Cultured; Clone Cells; Diterpenes; Epidermal Cells; Humans; Keratins; Kinetics; Mice; Retinyl Esters; Tretinoin; Vitamin A

The in vitro proliferation of herpesvirus-transformed marmoset lymphoblastoid cell lines (LCL) was inhibited by retinoic acid and retinyl acetate. Both Herpesvirus-ateles-and Herpesvirus-saimiri-transformed LCL with T-cell characteristics and Epstein-Barr-transformed LCL with B-cell markers were more sensitive to retinoic acid than to retinyl acetate. Inhibition of LCL proliferation was dependent on retinoid concentration and became apparent only after 3-4 days of exposure. In vitro assays for marmoset LCL sensitivity to retinoids may indicate the potential usefulness of these compounds in the chemoprevention of virus-induced lymphoma in vivo.

Topics: Animals; Callitrichinae; Cell Division; Cell Line; Cell Survival; Cell Transformation, Viral; Diterpenes; Herpesviridae; Herpesvirus 4, Human; In Vitro Techniques; Lymphocyte Activation; Lymphocytes; Retinyl Esters; Tretinoin; Vitamin A

Retinol at concentrations of 10(-6) and 10(-5) M stimulated growth of bovine aortic endothelial cells maintained in Eagle's MEM supplemented with delipidized serum. In addition to retinol, retinal, retinoic acid, and retinyl acetate were also growth stimulatory. At very low inoculum densities (4-40 cells/cm2) the growth promoting effect could be demonstrated only in the presence of conditioned medium from macrophage-like culture P388D1. When added to media containing whole (nondelipidized) serum, retinol was growth inhibitory at 10(-6) and 10(-5) M concentrations.

Topics: Animals; Aorta; Blood; Cattle; Cell Division; Cells, Cultured; Culture Media; Diterpenes; Endothelium; Fibroblast Growth Factors; Peptides; Retinaldehyde; Retinyl Esters; Stimulation, Chemical; Tretinoin; Vitamin A

Topics: Animals; Cell Adhesion; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Diterpenes; Methylcholanthrene; Mice; Mice, Inbred C3H; Retinaldehyde; Retinyl Esters; Tretinoin; Vitamin A

All-trans-[3H]retinyl acetate has been shown to be metabolized to all-trans-[3H]retinoic acid in a target tissue of vitamin A action, the hamster trachea in organ culture. That the compound produced is indeed all-trans-retinoic acid is demonstrated by chromatography of the biosynthetically produced retinoic acid with synthetic all-trans-retinoic acid in two different high-pressure liquid chromatographic systems, either as the free acids in a reverse-phase system or as the methyl esters in a normal-phase system. The all-trans-[3H]retinoic acid was also found in the tracheal epithelium and cartilage as well as in the medium. In addition the tracheal tissue also contained retinyl palmitate and other esters. Finally, further in vitro metabolism of [3H]retinyl acetate paralleled the metabolism of [14C]retinoic acid suggesting that these two compounds are being metabolized through similar pathways.

Topics: Animals; Carbon Radioisotopes; Cricetinae; Diterpenes; Kinetics; Organ Culture Techniques; Retinyl Esters; Trachea; Tretinoin; Tritium; Vitamin A

Various natural and synthetic retinoids have been studied for their activity in two biological systems: (a) their activity as inhibitors of methylcholanthrene-induced neoplastic transformation in the C3H/10T1/2 clone 8 mouse fibroblast line (System 1); and (b) their ability to increase the degree of adhesion of C3H/10T1/2 clone 8 cells to a plastic substrate (System 2). These activities were then compared with their known activity in maintaining epithelial differentiation (System 3). With the notable exception of retinoic acid and 13-cis-retinoic acid, which were inactive in Systems 1 and 2, an excellent correlation was observed between activities in Systems 1 and 3 for retinyl acetate, N-(4-hydroxyphenyl)retinamide, retinylidene dimedone, N-ethylretinamide, and N-benzoylretinylamine. Compounds shown to be inactive in System 1 had little or no activity in System 2. However, the ability of retinoids to cause increased adhesion could not be correlated with Systems 1 or 3 in all cases. For instance, retinyl acetate was highly active in Systems 1, 2, and 3, whereas retinylidene dimedone was highly active in Systems 1 and 3 but weakly active in System 2. Conversely, N-(4-hydroxyphenyl)retinylamide was highly active in Systems 1 and 3 but caused a decrease in System 2. The lack of activity of 3 but caused a decrease in System 2. The lack of activity of retinoic acid isomers in the C3H/10T1/2 clone 8 system is paradoxical and may provide important information on requirements for their activation and/or transport.

Topics: Amides; Animals; Cell Adhesion; Cell Line; Cell Transformation, Neoplastic; Diterpenes; Fenretinide; Isotretinoin; Methylcholanthrene; Mice; Neoplasms, Experimental; Retinoids; Retinyl Esters; Structure-Activity Relationship; Tretinoin; Vitamin A

Retinoic acid, retinol, retinyl acetate, and retinal induced activities of lysosomal enzymes, such as lysozyme, acid protease, and acid phosphatase, in mouse myeloid leukemia cells (M1), while the pyridyl analog of retinoic acid had no effect. Retinoic acid was the most potent inducer of lysosomal enzyme activities. The induction of lysozyme activity by retinoic acid was inhibited by treatment with puromycin. The retinoids did not induce phagocytic and locomotive activities or morphological changes in M1 cells, and they inhibited the induction of these differentiation-associated properties by various inducers without inhibiting cell growth. Retinoic acid was the most potent inhibitor of induction of these differentiation-associated properties. The inhibitory effect of retinoic acid was found to be reversible. These results suggest that distinct mechanisms exist for control of induction of lysosomal enzyme activities and of other differentiation-associated properties of M1 cells, such as phagocytosis, morphological changes, and migration.

Topics: Animals; Cell Differentiation; Cell Line; Cell Movement; Dexamethasone; Diterpenes; Leukemia, Experimental; Leukemia, Myeloid; Lysosomes; Mice; Phagocytosis; Retinaldehyde; Retinyl Esters; Tretinoin; Vitamin A

The effects of level and feeding frequency of retinoic acid (OIC) or retinyl acetate (YL) on the accumulation of lipids in the serum and liver of rats were investigated. Male Sprague-Dawley rats were fed ad libitum 1% cholesterol diets with or without supplemental OIC or YL. Vitamin A-fed groups included (per g of dry diet): 105 microgram of OIC or 113 microgram YL daily for 28 days, 735 microgram OIC or 791 microgram YL once each week for 28 days; and 735 or 105 microgram OIC on day 1 or 105 microgram OIC daily for the week experiment. Daily feeding of OIC or YL increased serum triglyceride concentrations as compared to conrols. Several days after removal of OIC or 1 week after removal of supplemental YL from the rat diets, serum triglyceride concentrations returned to basal levels. Cholesterol feeding elevated serum cholesterol as well as hepatic cholesterol, total lipids and vitamin A concentrations. Daily OIC feeding depressed serum and hepatic cholesterol concentrations. These results show that daily supplement of vitamin A increased serum triglycerides and reduced serum and hepatic cholesterol concentrations. Serum and liver alterations were dependent on continued feeding.

Topics: Animals; Cholesterol; Cholesterol, Dietary; Diterpenes; Female; Hyperlipidemias; Lipid Metabolism; Liver; Organ Size; Phospholipids; Rats; Retinyl Esters; Tretinoin; Triglycerides; Vitamin A

Topics: Amides; Anemia; Animals; Blood Glucose; Diterpenes; Enzymes; Female; Fractures, Bone; Granulocytes; Leukocytosis; Liver; Male; Mice; Retinyl Esters; Serum Albumin; Tretinoin; Vitamin A

The effects of retinyl acetate on the biosynthesis of sulfated glycosaminoglycans in dermal and epidermal cells isolated from newborn mice was investigated. Three compartments were analysed for [35S]-glycosaminoglycans; the culture medium, the cellular matrix, and the cells. The individual levels of chondroitin 4-sulfate, dermatan sulfate and heparin and/or heparan sulfate in these compartments as a function of retinyl acetate was also analysed. The addition of retinyl acetate resulted in a dose dependent increase 35SO4 incorporation in the cellular and matrix compartments of the dermis in vitro. At the optimum concentration of 1.8 X 10(-6) M, this increase was 50%. The levels of35SO4 incorporated into medium glycosaminoglycans were relatively constant. There were also changes in the levels of the individual sulfated glycosaminoglycans. The glycosaminoglycan profile was modified differently in each of the three compartments analysed. In the epidermal cells, retinyl acetate at an optimum concentration of 1.8 X 10(-6) M resulted in a dose dependent increase in 35SO4 incorporation in the cellular, matrix and medium compartments. There was no apparent change in the glycosaminoglycan profile, with heparin and/or heparan sulfate being the major sulfated glycosaminoglycan.

Topics: Cell Count; Cells, Cultured; Diterpenes; Epidermal Cells; Epidermis; Glycosaminoglycans; Retinyl Esters; Skin; Tretinoin; Vitamin A

The in vitro proliferation of murine melanoma cell lines S91 and B16 was inhibited by retinoic acid and retinyl acetate. The inhibitory effects were dependent on retinoid concentration and increased from 55 and 30% at 10(-9) M retinoic acid to 85 and 82% at 10(-5) M retinoic acid for S91 and B16 melanoma cells, respectively. S91 melanoma cells were more sensitive than B16 melanoma cells to inhibition by either retinoid, and both cell lines were more sensitive to retinoic acid than to retinyl acetate. When exposed to 10(-5) M retinoic acid, the two cell types grew at the same rate as did control cells for 48 hours, whereupon the growth rates of retinoid-treated cells decreased. After 6 days, the number of cells in control cultures increased 140 times (S91 melanoma cells) and 265 times (B16 melanoma cells), whereas retinoic acid-treated cells increased only 14 times (S91 melanoma cells) and 40 times (B16 melanoma cells). The degree of growth inhibition by retinoic acid was not dependent on initial cell density. Cortisone and hydrocortisone failed to prevent or reduce the inhibitory effect of retinoic acid; the release of lysosomal acid phosphatase was not increased and the intracellular level of 3',5'-cyclic AMP in cells grown for 5 days in the presence of 10(-5) M retinoic acid was not elevated. Viability of S91 and B16 cells after 8 days' exposure to 10(-5) M retinoic acid was similar to that in control cultures. The reduced growth rate of retinoic acid-treated cells reversed to the control rate 48-72 hours after removal of retinoic acid from the growth medium.

Topics: Animals; Cell Division; Cell Line; Cortisone; Cyclic AMP; Diterpenes; Dose-Response Relationship, Drug; Drug Interactions; Hydrocortisone; Kinetics; Melanoma; Mice; Neoplasms, Experimental; Retinyl Esters; Tretinoin; Vitamin A

Both retinoic acid and retinyl acetate, administered in high doses on days 13--15 of gestation, are capable of causing a 90 per cent incidence of cleft palate in Charles River rats. However, an attempt to develop as in vivo rabbit model system for the induction of clefts via hypervitaminosis A was unsuccessful. In the rat, the retinoic acid form of vitamin A is the more potent teratogen, inducing clefts at less than half the dose required to produce them with retinyl acetate. Histologic examination of fetal rat heads confirmed the biochemical evidence that retinoic acid is the more potent teratogen. Both forms of vitamin A prevented palatal shelf reorientation from occurring at the correct gestational age. The retinyl acetate treatment delayed the rotation for approximately 12 hours, the retinoic acid for at least 48 hours.

Topics: Animals; Cleft Palate; Disease Models, Animal; Diterpenes; Palate; Rabbits; Rats; Retinaldehyde; Retinyl Esters; Teratogens; Tretinoin; Vitamin A

Topics: Animals; Antineoplastic Agents; Cell Division; Cell Line; Cell Transformation, Neoplastic; Diterpenes; DNA, Neoplasm; Mammary Neoplasms, Experimental; Melanoma; Neoplasm Proteins; Neoplasms, Experimental; Retinol-Binding Proteins; Retinyl Esters; Sarcoma, Experimental; Tretinoin; Vitamin A

After partial hepatectomy the net increase in tissue weight and in RNA, DNA and proteins in the regenerating liver was markedly less in vitamin A-deleted or retinoic acid-supplemented male rats, compared with the corresponding normal control or retinyl acetate-supplemented ones.

Topics: Acetates; Animals; Diterpenes; DNA; Esters; Fatty Acids, Unsaturated; Haplorhini; Hepatectomy; Liver; Liver Regeneration; Male; Proteins; Retinyl Esters; RNA; Time Factors; Tretinoin; Vitamin A