rimorphin and preproenkephalin

Neuropeptides induce signal transduction across the plasma membrane by acting through cell-surface receptors. The dynorphins, endogenous ligands for opioid receptors, are an exception; they also produce non-receptor-mediated effects causing pain and neurodegeneration. To understand non-receptor mechanism(s), we examined interactions of dynorphins with plasma membrane. Using fluorescence correlation spectroscopy and patch-clamp electrophysiology, we demonstrate that dynorphins accumulate in the membrane and induce a continuum of transient increases in ionic conductance. This phenomenon is consistent with stochastic formation of giant (~2.7 nm estimated diameter) unstructured non-ion-selective membrane pores. The potency of dynorphins to porate the plasma membrane correlates with their pathogenic effects in cellular and animal models. Membrane poration by dynorphins may represent a mechanism of pathological signal transduction. Persistent neuronal excitation by this mechanism may lead to profound neuropathological alterations, including neurodegeneration and cell death.

Topics: Analgesics, Opioid; Animals; Cell Membrane; Dynorphins; Endorphins; Enkephalins; Humans; Ligands; Microscopy, Confocal; Neuropeptides; Opioid Peptides; PC12 Cells; Protein Precursors; Rats; Signal Transduction

Dynorphins, endogenous peptides for the kappa opioid receptor, play important roles in many physiological and pathological functions. Here, we examined how prolonged treatment with three major prodynorphin peptides, dynorphin A (1-17) (Dyn A), dynorphin B (1-13) (Dyn B) and alpha-neoendorphin (alpha-Neo), regulated the human kappa opioid receptor (hKOR) stably expressed in Chinese hamster ovary (CHO) cells. Results from receptor binding and [(35)S]GTPgammaS binding assays showed that these peptides were potent full agonists of the hKOR with comparable receptor reserve and intrinsic efficacy to stimulate G proteins. A 4-h incubation with alpha-Neo at a concentration of approximately 600xEC(50) value (from [(35)S]GTPgammaS binding) resulted in receptor down-regulation to a much lower extent than the incubation with Dyn A and Dyn B at comparable concentrations ( approximately 10% vs. approximately 65%). Extending incubation period and increasing concentrations did not significantly affect the difference. The plateau level of alpha-Neo-mediated receptor internalization (30 min) was significantly less than those of Dyn A and Dyn B. Omission of the serum from the incubation medium or addition of peptidase inhibitors into the serum-containing medium enhanced alpha-Neo-, but not Dyn A- or Dyn B-, mediated receptor down-regulation and internalization; however, the degrees of alpha-Neo-induced adaptations were still significantly less than those of Dyn A and Dyn B. Thus, these endogenous peptides differentially regulate KOR after activating the receptor with similar receptor occupancy and intrinsic efficacy. Both stability in the presence of serum and intrinsic capacity to promote receptor adaptation play roles in the observed discrepancy among the dynorphin peptides.

Topics: Animals; Binding, Competitive; Blotting, Western; CHO Cells; Cricetinae; Cricetulus; Down-Regulation; Dynorphins; Electrophoresis, Polyacrylamide Gel; Endorphins; Enkephalins; Flow Cytometry; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Ligands; Peptides; Protease Inhibitors; Protein Precursors; Receptors, Opioid, kappa

The prodynorphin gene and its product, dynorphin B, have been found to promote cardiogenesis in embryonic cells by inducing the expression of GATA-4 and Nkx-2.5, two transcription factor-encoding genes essential for cardiogenesis. The molecular mechanism(s) underlying endorphin-induced cardiogenesis remain unknown. In the present study, we found that GTR1 embryonic stem (ES) cells expressed cell surface kappa opioid receptors, as well as protein kinase C (PKC)-alpha, -beta1, -beta2, -delta, -epsilon, and -zeta. Cardiac differentiation was associated with a marked increase in the Bmax value for a selective opioid receptor ligand and complex subcellular redistribution of selected PKC isozymes. PKC-alpha, -beta1, -beta2, -delta, and -epsilon all increased in the nucleus of ES-derived cardiac myocytes, compared with nuclei from undifferentiated cells. In both groups of cells, PKC-delta and -epsilon were mainly expressed at the nuclear level. The nuclear increase of PKC-alpha, -beta1, and -beta2 was due to a translocation from the cytosolic compartment. In contrast, the increase of both PKC-delta and PKC-epsilon in the nucleus of ES-derived cardiomyocytes occurred independently of enzyme translocation, suggesting changes in isozyme turnover and/or gene expression during cardiogenesis. No change in PKC-zeta expression was observed during cardiac differentiation. Opioid receptor antagonists prevented the nuclear increase of PKC-alpha, PKC-beta1, and PKC-beta2 and reduced cardiomyocyte yield but failed to affect the nuclear increase in PKC-delta and -epsilon. PKC inhibitors prevented the expression of cardiogenic genes and dynorphin B in ES cells and abolished their development into beating cardiomyocytes.

Topics: Animals; Cell Differentiation; Cell Line; Cell Nucleus; Dynorphins; Embryo, Mammalian; Embryo, Nonmammalian; Endorphins; Enkephalins; Enzyme Inhibitors; Gene Expression Regulation, Developmental; Heart; Isoenzymes; Myocytes, Cardiac; Myosin Heavy Chains; Narcotic Antagonists; Protein Kinase C; Protein Precursors; Receptors, Opioid, kappa; RNA, Messenger; Signal Transduction; Stem Cells

The cardiac differentiation of embryonic stem (ES) cells was found to involve prodynorphin gene and dynorphin B expression and was associated with the interaction of secreted dynorphin B with cell surface opioid receptors coupled with protein kinase C (PKC) signaling and complex subcellular redistribution patterning of selected PKC isozymes. Here, confocal microscopy revealed the presence of immunoreactive dynorphin B-like material in GTR1 ES cells, suggesting that dynorphin peptides may also act intracellularly. Opioid binding sites were identified in ES cell nuclei, with a single dissociation constant in the low nanomolar range. A significant increase in Bmax for a kappa opioid receptor ligand was observed in nuclei isolated from ES-derived cardiomyocytes compared with nuclei from undifferentiated cells. Direct exposure of nuclei isolated from undifferentiated ES cells to dynorphin B or U-50,488H, a synthetic kappa opioid receptor agonist, time- and dose-dependently activated the transcription of GATA-4 and Nkx-2.5, 2 cardiac lineage-promoting genes. Nuclear exposure to dynorphin B also enhanced the rate of prodynorphin gene transcription. These responses were abolished in a stereospecific fashion by the incubation of isolated nuclei with selective opioid receptor antagonists. Nuclei isolated from undifferentiated cells were able to phosphorylate the acrylodan-labeled MARCKS peptide, a high-affinity fluorescent PKC substrate. Exposure of isolated nuclei to dynorphin B induced a remarkable increase in nuclear PKC activity, which was suppressed by opioid receptor antagonists. Nuclear treatment with PKC inhibitors abolished the capability of dynorphin B to prime the transcription of cardiogenic genes.

Topics: Animals; Cell Differentiation; Cell Line; Cell Lineage; Cell Nucleus; DNA-Binding Proteins; Dynorphins; Embryo, Mammalian; Embryo, Nonmammalian; Endorphins; Enkephalins; Enzyme Activation; GATA4 Transcription Factor; Gene Expression Regulation, Developmental; Heart; Homeobox Protein Nkx-2.5; Homeodomain Proteins; Myocytes, Cardiac; Protein Kinase C; Protein Precursors; Receptors, Opioid; RNA, Messenger; Signal Transduction; Stem Cells; Transcription Factors; Transcriptional Activation; Xenopus Proteins

Environmental manipulations early in life may induce persistent alterations in adult behaviour and physiology. The underlying neural mechanisms of these responses are not yet clear. We have previously reported long-term changes in brain opioid peptide levels in male and female Sprague-Dawley rats after short periods (15 min, known as neonatal handling) of maternal separation (MS) until weaning. To study this further, we investigated behavioural and neurochemical effects of repeated MS in male Wistar rats. The rat pups were separated from their dams in litters for either 360 min (MS360) or 15 min (MS15) daily from postnatal day 1 to 21 or exposed to normal animal facility rearing. Behavioural analysis showed that MS360 rats had increased ultrasonic calls on postnatal day 5 compared to MS15 rats, but not on postnatal day 6. Moreover, the MS360 rats had more animals with higher frequency of calls at day 5 than 6 than the MS15 rats. Analysis of the opioid peptides dynorphin B and Met-enkephalin-Arg(6)Phe(7) with radioimmunoassay 7 weeks after the MS procedure, revealed long-term neurochemical changes in several brain areas and in the pituitary gland. Immunoreactive dynorphin B and Met-enkephalin-Arg(6)Phe(7) levels were affected in the hypothalamus and dynorphin B levels in the neurointermediate pituitary lobe, amygdala, substantia nigra and the periaqueductal gray. Together, these findings show that repeated periods of MS early in life in male Wistar rats affect the development of the ultrasonic call response and induce long-lasting and possibly permanent alterations in the opioid peptide systems.

Topics: Animals; Animals, Newborn; Behavior, Animal; Body Weight; Brain; Corticosterone; Dynorphins; Endorphins; Enkephalin, Methionine; Enkephalins; Female; Male; Maternal Deprivation; Opioid Peptides; Pituitary Gland; Protein Precursors; Radioimmunoassay; Rats; Rats, Wistar; Time Factors; Ultrasonics

Intrathecal (i.t.) administration of big dynorphin (1-10 fmol), a prodynorphin-derived peptide consisting of dynorphin A and dynorphin B, to mice produced a characteristic behavioral response, the biting and/or licking of the hindpaw and the tail along with slight hindlimb scratching directed toward the flank, which peaked at 5-15 min after an injection. Dynorphin A produced a similar response, though the doses required were higher (0.1-30 pmol) whereas dynorphin B was practically inactive even at 1000 pmol. The behavior induced by big dynorphin (3 fmol) was dose-dependently inhibited by intraperitoneal injection of morphine (0.125-2 mg/kg) and also dose-dependently, by i.t. co-administration of D(-)-2-amino-5-phosphonovaleric acid (D-APV) (1-4 nmol), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 (0.25-4 nmol), an NMDA ion-channel blocker, and ifenprodil (2-8 pmol), an inhibitor of the NMDA receptor ion-channel complex interacting with the NR2B subunit and the polyamine recognition site. On the other hand, naloxone, an opioid receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA glutamate receptor antagonist, 7-chlorokynurenic acid, a competitive antagonist of the glycine recognition site on the NMDA receptor ion-channel complex, [D-Phe(7),D-His(9)]-substance P(6-11), a specific antagonist for substance P (NK1) receptors, and MEN-10376, a tachykinin NK2 receptor antagonist, had no effect. These results suggest that big dynorphin-induced nociceptive behavior is mediated through the activation of the NMDA receptor ion-channel complex by acting on the NR2B subunit and/or the polyamine recognition site but not on the glycine recognition site, and does not involve opioid, non-NMDA glutamate receptor mechanisms or tachykinin receptors in the mouse spinal cord.

Topics: 2-Amino-5-phosphonovalerate; 6-Cyano-7-nitroquinoxaline-2,3-dione; Analgesics, Opioid; Animals; Behavior, Animal; Dizocilpine Maleate; Dynorphins; Endorphins; Enkephalins; Excitatory Amino Acid Antagonists; Injections, Spinal; Kynurenic Acid; Male; Mice; Morphine; Neurokinin A; Nociceptors; Peptide Fragments; Piperidines; Protein Precursors; Receptors, N-Methyl-D-Aspartate; Receptors, Tachykinin; Substance P

Zinc finger-containing transcription factor GATA-4 and homeodomain Nkx-2.5 govern crucial developmental fates and have been found to promote cardiogenesis in embryonic cells exposed to the differentiating agent DMSO. Nevertheless, intracellular activators of these transcription factors are largely unknown. In this study, pluripotent P19 cells expressed the prodynorphin gene, an opioid gene encoding for the dynorphin family of opioid peptides. P19 cells were also able to synthesize and secrete dynorphin B, a biologically active end product of the prodynorphin gene. DMSO-primed GATA-4 and Nkx-2.5 gene expression was preceded by a marked increase in prodynorphin gene expression and dynorphin B synthesis and secretion. The DMSO effect occurred at the transcriptional level. In the absence of DMSO, dynorphin B triggered GATA-4 and Nkx-2.5 gene expression and led to the appearance of both alpha-myosin heavy chain and myosin light chain-2V transcripts, two markers of cardiac differentiation. Moreover, dynorphin B-exposed cells were positively stained in the presence of MF 20, a mouse monoclonal antibody raised against the alpha-myosin heavy chain. Opioid receptor antagonism and inhibition of opioid gene expression by a prodynorphin antisense phosphorothioate oligonucleotide blocked DMSO-induced cardiogenesis, suggesting an autocrine role of an opioid gene in developmental decisions.

Topics: Animals; Autocrine Communication; Cell Differentiation; Dimethyl Sulfoxide; DNA-Binding Proteins; Dynorphins; Endorphins; Enkephalins; Fetal Heart; Fetal Proteins; GATA4 Transcription Factor; Gene Expression Regulation, Developmental; Homeobox Protein Nkx-2.5; Homeodomain Proteins; Mice; Oligonucleotides, Antisense; Opioid Peptides; Protein Precursors; Recombinant Fusion Proteins; RNA, Messenger; Stem Cells; Thionucleotides; Transcription Factors; Transfection; Xenopus Proteins; Zinc Fingers

Prodynorphin mRNA and dynorphin B expression have been previously shown to be greatly increased in cardiac myocytes of BIO 14.6 cardiomyopathic hamsters. Here we report that exogenous dynorphin B induced a dose-dependent increase in prodynorphin mRNA levels and stimulated prodynorphin gene transcription in normal hamster myocytes. Similar responses were elicited by the synthetic selective kappa opioid receptor agonist U-50,488H. These effects were counteracted by the kappa opioid receptor antagonist Mr-1452 and were not observed in the presence of chelerythrine or calphostin C, two specific protein kinase C (PKC) inhibitors. Treatment of cardiomyopathic cells with Mr-1452 significantly decreased both prodynorphin mRNA levels and prodynorphin gene transcription. In control myocytes, dynorphin B induced the translocation of PKC-alpha to the nucleus and increased nuclear PKC activity without affecting the expression of PKC-delta, -epsilon, or -zeta. Acute release of either U-50,488H or dyn B over single normal or cardiomyopathic cells transiently increased the cytosolic Ca2+ concentration. A sustained treatment with each opioid agonist increased the cytosolic Ca2+ level for a more prolonged period in cardiomyopathic than in control myocytes and led to a depletion of Ca2+ from the sarcoplasmic reticulum in both groups of cells. The possibility that prodynorphin gene expression may affect the function of the cardiomyopathic cell through an autocrine mechanism is discussed.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Calcium; Cardiomyopathy, Hypertrophic; Cell Compartmentation; Cell Nucleus; Cricetinae; Cytosol; Dynorphins; Endorphins; Enkephalins; Enzyme Inhibitors; Gene Expression; Mesocricetus; Myocardium; Protein Kinase C; Protein Precursors; Pyrrolidines; Receptors, Opioid, kappa; Ryanodine; Sarcoplasmic Reticulum

The levels of dynorphin A-like immunoreactivity (Dyn A-LI) and dynorphin B-like immunoreactivity (Dyn B-LI) were determined in various regions of brain, spinal cord and pituitary gland in spontaneously hypertensive rats (SHRs) as compared with the normotensive Wistar-Kyoto rats (WKYs). SHRs had significantly lower levels of Dyn A-LI and Dyn B-LI in the neurointermediate pituitary lobe and in the hippocampus. Conversely, the levels of Dyn A-LI and Dyn B-LI were higher in the hypothalamus, striatum and periaqueductal gray of the SHRs.

Topics: Animals; Biomarkers; Brain; Dynorphins; Endorphins; Enkephalins; Hypertension; Immunohistochemistry; Lumbosacral Region; Male; Pituitary Gland; Protein Precursors; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Spinal Cord

Research has suggested that exogenous opioid substances can have direct effects on cardiac muscle or influence neurotransmitter release via presynaptic modulation of neuronal inputs to the heart. In the present study, multiple-labelling immunohistochemistry was employed to determine the distribution of endogenous opioid peptides within the guinea-pig heart. Approximately 40% of cardiac ganglion cells contained immunoreactivity for dynorphin A (1-8), dynorphin A (1-17) and dynorphin B whilst 20% displayed leu-enkephalin immunoreactivity. Different populations of opioid-containing ganglion cells were identified according to the co-existence of opioid immunoreactivity with immunoreactivity for somatostatin and neuropeptide Y. Immunoreactivity for prodynorphin-derived peptides was observed in many sympathetic axons in the heart and was also observed, though to a lesser extent, in sensory axons. Leu-enkephalin immunoreactivity was observed in occasional sympathetic and sensory axons. No immunoreactivity was observed for met-enkephalin-arg-gly-leu or for beta-endorphin. These results demonstrate that prodynorphin-derived peptides are present in parasympathetic, sympathetic and sensory nerves within the heart, but suggest that only the prodynorphin gene is expressed in guinea-pig cardiac nerves. This study has shown that endogenous opioid peptides are well placed to regulate cardiac function via both autonomic and sensory pathways.

Topics: Adrenergic Fibers; Animals; Antibody Specificity; Axons; beta-Endorphin; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalin, Methionine; Enkephalins; Female; Ganglia, Autonomic; Guinea Pigs; Heart; Immunohistochemistry; Male; Neurons, Afferent; Opioid Peptides; Parasympathetic Fibers, Postganglionic; Protein Precursors

The main purpose of this study was to investigate differences regarding endogenous opioids in post-mortem frontal cortex of adult patients with Down syndrome (DS), patients with Alzheimer disease (AD) and neurologically healthy persons, respectively, using specific radioimmunoassays. The results of this study show that there is an increase in the levels of leu-enkephalin and dynorphin A in the frontal cortex of patients with DS as compared to the control group. An almost identical increase was also observed when comparing patients with AD to controls. In conclusion, the results of this study suggest a relationship between elevated tissue levels of leuenkephalin and dynorphin A in cerebral cortex and cognitive impairments in patients with DS and AD.

Topics: Aged; Alzheimer Disease; Down Syndrome; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalin, Methionine; Enkephalins; Female; Frontal Lobe; Gene Expression Regulation; Humans; Male; Middle Aged; Protein Precursors; Radioimmunoassay

Most adrenal chromaffin cells synthesize opioids derived from proenkephalin but not from prodynorphin. However, human pheochromocytomas and the PC12 rat pheochromocytoma cell line synthesize dynorphins. The aim of this study was to confirm the presence of the authentic prodynorphin transcript and its dynorphin product in PC12 cells. We have found that the sequence of a 458 bp cDNA fragment derived from RT-PCR amplification of total PC12 RNA was in complete accordance with the published sequence of the equivalent region of the prodynorphin gene. It encodes the potent endogenous kappa opioid agonists alpha-neo-endorphin, dynorphin A and dynorphin B. Furthermore, immunoaffinity-purified PC12 cell extracts were subjected to RP-HPLC. Most of its IR-dynorphin eluted on a peak exhibiting the retention time of similarly treated rat anterior pituitary. The expression of the prodynorphin gene in pheochromocytomas can be explained as either the result of (a) the process of dedifferentiation of chromaffin cells to pheochromocytoma which may thus cause the expression of a previously unexpressed prodynorphin or that (b) those pheochromocytomas expressing the prodynorphin gene derive from the few, centrally located chromaffin cells, which express this gene even under normal conditions.

Topics: Adrenal Medulla; Animals; Chromatography, Affinity; Chromatography, High Pressure Liquid; Dynorphins; Endorphins; Enkephalins; Gene Expression; PC12 Cells; Pheochromocytoma; Pituitary Gland; Polymerase Chain Reaction; Protein Precursors; Rats; Sequence Analysis

Pharmacological studies suggest that diabetes produces changes in the brain opioid system, affecting several behavioral functions including analgesia, feeding and self-stimulation. Previous investigations of opioid receptor binding have failed to explain the unusual opioid pharmacology of the diabetic animal. In the present study, the effects of streptozotocin-induced diabetes on levels of three immunoreactive (ir)-prodynorphin-derived peptides, ir-dynorphin A1-17 (A1-17), ir-dynorphin A1-8 (A1-8) and ir-dynorphin B1-13 (B1-13), were determined in eleven brain regions known to be involved in appetite, taste and reward. Diabetes was found to increase levels of A1-17 in the ventromedial and dorsomedial hypothalamic nuclei (+60% and +25%, respectively) and levels of A1-8 in the dorsomedial and lateral hypothalamus (+45% and +35%, respectively). The possible significance of these results is discussed in relation to (i) diabetic hyperphagia, (ii) medial hypothalamic transduction of circulating insulin levels, and (iii) the potentiation of reward by metabolic need states.

Topics: Animals; Brain; Diabetes Mellitus, Experimental; Dynorphins; Enkephalins; Hypothalamic Hormones; Male; Peptide Fragments; Protein Precursors; Rats; Rats, Sprague-Dawley

Dynorphin B (Dyn B-13, also known as rimorphin) is generated from Dyn B-29 (leumorphin) by the cleavage at a single Arg residue. An enzymatic activity capable of processing at this monobasic site has been previously reported in neurosecretory vesicles of the bovine pituitary and pituitary-derived cell lines. This enzyme termed "the dynorphin-converting enzyme" (DCE) has been purified to apparent homogeneity from the neurointermediate lobe of the bovine pituitary using hydrophobic chromatography on phenyl-Sepharose, preparative isoelectrofocusing in a granulated gel between pH 4 to 6.5, and non-denaturing electrophoresis on 5% polyacrylamide gel. DCE exhibits a pI of about 5.1 and a molecular mass of about 54 kDa under reducing conditions. DCE is a metallopeptidase and exhibits a neutral pH optimum. Specific Inhibitors of soluble metallopeptidases such as enkephalinase (EC 3.4.24.11) or enkephalin generating neutral endopeptidase (EC 3.4.24.15) do not inhibit DCE activity indicating that DCE is distinct from these two enzymes. Cleavage site determination with matrix-assisted laser desorption ionization time of flight (MALDITOF) mass spectrometry shows that DCE cleaves the Dyn B-29 N terminus to the Arg14 generating Dyn B-13 and Dyn B-(14-29). Among other peptides derived from Dyn B-29, DCE cleaves only those peptides that fit the predicted "consensus motif" for monobasic processing. These data are consistent with a broader role for the dynorphin converting enzyme in the biosynthesis of many peptide hormones and neuropeptides by processing at monobasic sites.

Topics: Amino Acid Sequence; Animals; Binding Sites; Cattle; Dynorphins; Endorphins; Enkephalins; Isoelectric Point; Kinetics; Molecular Sequence Data; Molecular Weight; Peptide Fragments; Pituitary Gland; Protein Precursors; Protein Processing, Post-Translational; Serine Endopeptidases; Substrate Specificity

Proteolytic processing of prodynorphin-derived peptides in rat brain was studied with the help of high performance size exclusion chromatography (SEC) connected to electrospray ionization mass spectrometry. Extracts from rat striatum were incubated with individual synthetic dynorphin peptides. Dynorphin A was the most resistant to proteolytic cleavage, converting slowly to Leu-enkephalin (0.3 pmol/min), whereas dynorphin B was processed to this pentapeptide at a 10(4)-fold higher rate. Minor cleavage was also observed between Arg6-Arg7. Alphaneoendorphin was also rapidly metabolized to Leu-enkephalin (6 nmol/min) and, to a lesser extent, to Leu-enkephalinArg6. This new strategy for studying peptidases can easily be adapted to identification of components present in body fluids.

Topics: Animals; Anti-Bacterial Agents; Chromatography, Gel; Corpus Striatum; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalins; Male; Mass Spectrometry; Peptide Hydrolases; Peptides; Protein Precursors; Rats; Sensitivity and Specificity; Tissue Extracts

Opioid peptide gene expression was characterized in adult rat ventricular cardiac myocytes that had been cultured in the absence or the presence of phorbol 12-myristate 13-acetate. The phorbol ester induced a concentration- and time-dependent increase of prodynorphin mRNA, the maximal effect being reached after 4 h of treatment. The increase in mRNA expression was suppressed by incubation of cardiomyocytes with staurosporine, a putative protein kinase C inhibitor, and was not observed when the cells were cultured in the presence of the inactive phorbol ester 4 alpha-phorbol 12,13-didecanoate. Incubation of cardiac myocytes with phorbol 12-myristate 13-acetate also elicited a specific and staurosporine-sensitive increase in immunoreactive dynorphin B, a biologically active end product of the precursor, both in the myocardial cells and in the culture medium. In vitro run-off transcription assays indicated that transcription of the prodynorphin gene was increased both in nuclei isolated from phorbol ester-treated myocytes and in nuclei isolated from control cells and then exposed to phorbol 12-myristate 13-acetate. No transcriptional effect was observed when cardiac myocytes or isolated nuclei where exposed to 4 alpha-phorbol 12,13-didecanoate. The phorbol ester-induced increase in prodynorphin gene transcription was prevented by pretreatment of myocytes or isolated nuclei with staurosporine, suggesting that myocardial opioid gene expression may be regulated by nuclear protein kinase C. In this regard, cardiac myocytes expressed protein kinase C-alpha, -delta, -epsilon, and -zeta, as shown by immunoblotting. Only protein kinase C-delta and protein kinase C-epsilon were expressed in nuclei that have been isolated from control myocytes, suggesting that these two isotypes of the enzyme may be part of the signal transduction pathway involved in the effect elicited by the phorbol ester on opioid gene transcription in isolated nuclei. The incubation of myocardial nuclei isolated from control cells in the presence of a protein kinase C activator induced the phosphorylation of the myristoylated alanine-rich protein kinase C substrate peptide, a specific fluorescent substrate of the enzyme. The possibility that prodynorphin gene expression may control the heart function through autocrine or paracrine mechanisms is discussed.

Topics: Alkaloids; Animals; Cell Nucleus; Cells, Cultured; Dose-Response Relationship, Drug; Dynorphins; Endorphins; Enkephalins; Enzyme Inhibitors; Gene Expression; Heart Ventricles; Isoenzymes; Kinetics; Male; Myocardium; Phorbol Esters; Protein Kinase C; Protein Precursors; Rats; Rats, Wistar; Staurosporine; Tetradecanoylphorbol Acetate; Transcription, Genetic

Chronic food restriction produces a variety of physiological and behavioral adaptations including a potentiation of the reinforcing effect of food, drugs and lateral hypothalamic electrical stimulation. Previous work in this laboratory has revealed that the lowering of self-stimulation threshold by food restriction is reduced by mu- and kappa-selective opioid antagonists. In the present study, the effect of chronic food restriction on levels of three prodynorphin-derived peptides, namely dynorphin A1-17 (A1-17), dynorphin A1-8 (A1-8) and dynorphin B1-13 (B1-13) were measured in eleven brain regions known to be involved in appetite, taste and reward. Food restriction increased levels of A1-17 in dorsal medial (+19.6%), ventral medial (+24.2%) and medial preoptic (+82.9%) hypothalamic areas. Levels of A1-17 decreased in the central nucleus of the amygdala (-35.1%). Food restriction increased levels of A1-8 in nucleus accumbens (+34.4%), bed nucleus of the stria terminalis (+24.5%) and lateral hypothalamus (+41.9%). Food restriction had no effect on levels of B1-13. A1-17 is highly kappa-preferring and the brain regions in which levels increased all have a high ratio of kappa: mu and delta receptors. A1-8 is less discriminating among opioid receptor types and the brain regions in which levels increased have a low ratio of kappa: mu and delta receptors. The present results suggest that food restriction alters posttranslational processing within the dynorphin A domain of the prodynorphin precursor, possibly leading to a change in the balance between kappa and non-kappa opioid receptor stimulation in specific brain regions.

Topics: Animals; Diet; Dynorphins; Enkephalins; Hypothalamic Hormones; Male; Neuropeptides; Peptide Fragments; Protein Precursors; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Time Factors

The distributions of four prodynorphin-derived peptides, dynorphin A (1-17), dynorphin A (1-8), dynorphin B, and alpha-neo-endorphin were determined in 10 cortical regions and the striatum of the old world monkey (Macaca nemestrina). alpha-neo-endorphin was the most abundant peptide in both cortex and striatum. The concentrations of all four peptides were significantly greater in the striatum compared to the cortex. In general, concentrations of each peptide tended to be higher in allocortex than in neocortex. Possible inter- and intradomain processing differences, as estimated by ratios of these peptides, did not vary within cortex, but the intradomain peptide ratio, dyn A (1-17)/dyn A (1-8), was significantly greater in cortex than in striatum. These results indicate that prodynorphin is, in some ways, uniquely processed in the primate. Particularly unusual is the relatively low abundance of prodynorphin-derived products in the cortex, in the face of moderately high levels of kappa opiate receptor expression.

Topics: Animals; Cerebral Cortex; Corpus Striatum; Dynorphins; Endorphins; Enkephalins; Macaca nemestrina; Peptide Fragments; Protein Precursors; Tissue Distribution

The distributions and extent of processing of four prodynorphin-derived peptides (dynorphin A (1-17), dynorphin A (1-8), dynorphin B, and alpha-neoendorphin) were determined in ten regions of the cortex as well as in the striatum of the guinea-pig. There were significant differences between concentrations of these peptides in most cortical regions, with alpha-neoendorphin being several times more abundant than the other peptides, and dynorphin A (1-17) being present in the least amount. There were significant between-region differences in concentration for each peptide, although most regions had concentrations similar to those seen in the striatum. Concentrations of each peptide tended to be higher in piriform, entorhinal, motor, and auditory cortex than in other cortical regions. The extent of processing of prodynorphin varied across cortical regions as well, primarily due to the extent of processing to alpha-neoendorphin. Prodynorphin mRNA levels were not significantly different between cortical regions or from the amount observed in the striatum. Although specific regional variation exists, it appears that in general prodynorphin is expressed and processed in a similar manner in the cortex as in the striatum.

Topics: Animals; Blotting, Northern; Cerebral Cortex; Corpus Striatum; Dynorphins; Endorphins; Enkephalins; Guinea Pigs; Male; Organ Specificity; Peptide Fragments; Protein Precursors; Radioimmunoassay; RNA, Messenger

Guinea-pig ileum was dissected and the mucosa, submucosa and external musculature extracted with aqueous acetic acid for measurement of four prodynorphin-derived peptides, namely dynorphin A 1-8, dynorphin A 1-17, dynorphin B, and alpha-neoendorphin. The peptide-like immunoreactive material extracted from the external musculature was characterized by multi-dimensional chromatographic analysis and compared to synthetic porcine standards. The chromatographic methods utilized were: reversed-phase high performance liquid chromatography (RP-HPLC), using two different eluants; cation exchange high performance liquid chromatography (CE-HPLC) and gel filtration chromatography. The dynorphin A 1-8-like immunoreactive material was homogeneous and coeluted with the standard in all chromatographic modes. The dynorphin A 1-17-like and dynorphin B-like immunoreactive material was heterogeneous but showed a peak that coeluted with synthetic standard in all chromatographic modes. The alpha-neoendorphin-like immunoreactive material also appeared to be heterogeneous with the major component on CE-HPLC coeluting with the synthetic peptide standard while the major component on RP-HPLC eluted differently. It was concluded that the guinea-pig ileum contains immunoreactivity for peptides derived from all coding regions of the prodynorphin gene and that these peptides may be present in multiple immunoreactive forms.

Topics: Animals; Chromatography, Gel; Chromatography, High Pressure Liquid; Dynorphins; Endorphins; Enkephalins; Guinea Pigs; Ileum; Peptide Fragments; Protein Precursors; Radioimmunoassay

The neuroanatomical distribution of the prodynorphin precursor molecule in the forebrain of the male Syrian hamster (Mesocricetus auratus) has been studied with a novel antiserum directed against the C-terminus of the leumorphin [dynorphin B (1-29)] peptide product. C-peptide staining in sections from colchicine-treated hamsters is compared to staining in sections from untreated animals. In addition, the pattern of C-peptide immunostaining in hamster brain is compared to that in the rat brain. Finally, the C-peptide immunolabeling patterns in hamsters and rats are compared to those obtained with antisera to dynorphin A (1-17) and dynorphin B (1-13). Areas of heaviest prodynorphin immunoreactivity in the hamster include the hippocampal formation, lateral septum, bed nucleus of the stria terminalis, medial preoptic area, medial and central amygdaloid nuclei, ventral pallidum, substantia nigra, and numerous hypothalamic nuclei. Although this C-peptide staining pattern is similar to dynorphin staining reported previously in the rat, several species differences are apparent. Whereas moderate dentate gyrus granule cell staining and no CA4 cell staining have been reported in the rat hippocampal formation, intense immunostaining in the dentate gyrus and CA4 cell labeling are observed in the hamster. In addition, the medial preoptic area, bed nucleus of the stria terminalis, and medial nucleus of the amygdala stain lightly for prodynorphin-containing fibers and cells in the rat, compared to heavy cell and fiber staining in the hamster in all three of these regions. In the rat there is no differential staining between tissues processed with the C-peptide, dynorphin A, and dynorphin B antisera, but numerous areas of the hamster brain show striking differences. In most hamster brain areas containing prodynorphin peptides, the C-peptide antiserum immunolabels more cells and fibers than the dynorphin B antiserum, which in turn labels more cells and fibers than dynorphin A antiserum. However, exceptions to this hierarchy of staining intensity are found in the lateral hypothalamus, substantia nigra, arcuate nucleus, and habenula. The differences in staining patterns between rat and hamster are greatest when C-peptide antiserum is used; apparent species differences are present, though less pronounced, in dynorphin B- and dynorphin A-immunostained material.

Topics: Animals; Brain Chemistry; Colchicine; Cricetinae; Dynorphins; Endorphins; Enkephalins; Immune Sera; Immunoenzyme Techniques; Male; Mesocricetus; Peptide Fragments; Perfusion; Protein Precursors; Rats; Rats, Inbred Strains; Species Specificity

The contents of methionine-enkephalin-Arg-Gly-Leu, dynorphin A, dynorphin B and alpha-neoendorphin have been measured in both control and Huntington's disease brains obtained postmortem. All 4 peptides were significantly reduced in the caudate nucleus and putamen of Huntington's disease compared with the control group. No differences were observed in frontal cortex or hypothalamus. Immunocytochemistry showed a marked depletion of dynorphin-like immunoreactivity in Huntington's disease substantia nigra.

Topics: Basal Ganglia; Caudate Nucleus; Dynorphins; Endorphins; Enkephalins; Globus Pallidus; Humans; Huntington Disease; Protein Precursors; Putamen; Substantia Nigra

Dynorphin B (rimorphin) is formed from leumorphin (dynorphin B-29) by the action of a thiol protease from rat brain membranes, in a single step. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. We have observed that in addition to dynorphin B, dynorphin B-14 is formed from dynorphin B-29. Among the various protease inhibitors tested, none except p-chloromercuribenzensulfonic acid inhibited the formation of the two products. Both temperature and pH had similar effects on the formation of dynorphin B-14 and dynorphin B. The inhibitory potencies of adrenocorticotropic hormone, peptide E, and dynorphin A were virtually identical for the formation of the two products. These results suggest that the same enzyme may be responsible for the formation of dynorphin B-14 and dynorphin B.

Topics: Adrenocorticotropic Hormone; Cysteine Endopeptidases; Dynorphins; Endopeptidases; Endorphins; Enkephalins; Hydrogen-Ion Concentration; Peptides; Protease Inhibitors; Protein Precursors; Temperature

The total content of rat pituitary anterior lobe (AL) immunoreactive (ir) dynorphin A (ir-Dyn A) and ir-dynorphin B (Dyn B) increased in male rats between 15 and 58 days of age, but there was little alteration in the concentration of ir-Dyn A or B expressed relative to protein content. Adult rats (90 days of age) had lower concentrations of these peptide immunoreactivities in the AL. Castration of 58-day-old male rats produced a testosterone-reversible loss of ir-Dyn A and B by 50-60% 3 days after surgery. Thereafter, the levels of these peptides gradually increased to 2.5 times the levels found in control animals at 1 month after castration. These effects of castration on AL dynorphin were not seen in 15-day-old rats and were much less marked in adults. Similar changes were seen in the levels of other prodynorphin products, alpha- and beta-neo-endorphin (ir-alpha-nEnd and ir-beta-nEnd), and ir-[Leu5]enkephalin (ir-LE). Administration of testosterone (100 micrograms/100 g BW) to castrated rats for 2 days largely prevented the drop in the levels of AL ir-Dyn A and B. Ovariectomy produced an increase in the levels of ir-Dyn A, Dyn B, alpha-nEnd, beta-nEnd, and LE 2 weeks after surgery, but, in contrast to castration, no significant decrease was seen 3 days after ovariectomy. These changes in AL content of dynorphin-related peptides after castration or ovariectomy directly reflect those previously reported for AL content of LH. The mechanisms regulating storage (and perhaps secretion) of AL peptides derived from prodynorphin may be similar to those regulating storage and secretion of LH and FSH in rat AL. AL ir-LE could potentially arise from proenkephalin A or prodynorphin (proenkephalin B). Ir-LE levels in AL were approximately 10 times higher than the levels of ir-[Met5]-enkephalinyl-Arg-Gly-Leu (ME-RGL) in male rat AL, and changes in ir-LE content after castration were very similar to those observed in other prodynorphin-derived peptides, but different from the effects of castration on ir-ME-RGL. It is possible that prodynorphin is a major source of AL ir-LE.

Topics: Animals; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalins; Female; Gonadal Steroid Hormones; Male; Orchiectomy; Ovariectomy; Pituitary Gland, Anterior; Protein Precursors; Rats; Testosterone

Dynorphin B (rimorphin), a proenkephalin B (prodynorphin)-derived peptide, and met-enkephalin-Arg6, Gly7, Leu8 (met-enkephalin octapeptide), a proenkephalin A-derived peptide, were identified in the mammalian cochlea by specific radioimmunoassays. The antisera are directed against unique sequences in the peptides, and this immunoreactivity cannot be ascribed to cross-reaction with any other known opioid peptides. Met-enkephalin octapeptide and dynorphin B can for this reason serve as reliable markers for the proenkephalin A- and proenkephalin B-derived peptides, respectively. Lesion studies in the cochlea indicate that dynorphin B is confined to olivocochlear efferents. It has not been determined if the dynorphin-containing neurons are the same as those known to contain enkephalin-related peptides, or if they may be cholinergic. Different, presumably inhibitory, neurotransmitters or modulators in the olivocochlear fibers create the possibility of separately modulating the effects of inner or outer hair cells on auditory nerve activity, and so becoming able to study their individual actions in audition. The olivocochlear fiber-hair cell-eighth nerve interaction may provide a valuable model for a complex multi-transmitter synaptic junction.

Topics: Animals; Cochlea; Dynorphins; Endorphins; Enkephalin, Methionine; Enkephalins; Female; Guinea Pigs; Hair Cells, Auditory; Nerve Tissue Proteins; Protein Precursors

The effect of leumorphin (LM), one of big leu-enkephalins derived from preproenkephalin B, on PRL secretion was studied in the rat in vivo and in vitro. Intracerebroventricular injection of synthetic porcine LM (0.06-6 nmol/rat) caused a dose-related increase in plasma PRL levels in urethane-anesthetized male rats and in conscious freely moving rats. Intravenous injection of LM (3 nmol/100 g BW) also raised plasma PRL levels in these animals. The plasma PRL response to intracerebroventricular LM (0.6 nmol/rat) was blunted by naloxone (125 micrograms/100 g BW, iv). The stimulating effect of LM on PRL release was the most potent among the peptides derived from preproenkephalin B. In in vitro studies, PRL release from superfused anterior pituitary cells was stimulated in a dose-related manner by LM (10(-9)-10(-6) M), and the effect was blunted by naloxone (10(-5) M). These results suggest that LM has a potent stimulating effect on PRL secretion from the pituitary in the rat by acting, at least in part, directly at the pituitary through an opiate receptor.

Topics: Animals; beta-Endorphin; Dynorphins; Endorphins; Enkephalins; Injections, Intraventricular; Male; Naloxone; Pituitary Gland, Anterior; Prolactin; Protein Precursors; Rats; Swine; Thyrotropin-Releasing Hormone

Antibodies have been raised to a synthetic peptide corresponding to the C-terminal 15-amino acid residues of prodynorphin, the common precursor to the neo-endorphins and dynorphins. The amino acid sequence of the antigen was based on the sequence deduced from mRNA isolated and cloned from porcine hypothalamus (Kakidani, H., Y. Furutani, H. Takahashi, M. Noda, Y. Morimoto, T. Hirose, M. Asai, S. Inayama, S. Nakanishi, and S. Numa (1982) Nature 298: 245-248). Using a radioimmunoassay developed from these antibodies we have isolated an endogenous prodynorphin C-fragment from bovine caudate nucleus. The isolated peptide displayed characteristics on gel filtration similar to those of synthetic prodynorphin C-fragment predicted from the porcine mRNA sequence but had low cross-reactivity in the radioimmunoassay. Sequencing and amino acid analysis showed a substitution of serine for asparagine at position 6 in the porcine sequence. Dynorphin B (rimorphin), which is adjacent to prodynorphin C-fragment in the precursor, was isolated from the same extract. Amino acid analysis and elution position on a gel filtration column confirmed its structure as that previously characterized from bovine pituitary extracts. The release of prodynorphin C-fragment and the C-terminus of dynorphin B from the porcine precursor would require cleavage at a single arginine residue. However, a terminal arginine was not present on either of these prodynorphin peptides isolated from bovine caudate. The data would suggest that processing at a single arginine residue results in elimination of the arginine, a feature in common with processing at paired basic residues.

Topics: Animals; Cattle; Caudate Nucleus; Dynorphins; Endorphins; Enkephalins; Protein Precursors; Rabbits; Radioimmunoassay

Dynorphin B (rimorphin) is formed from dynorphin B-29 (leumorphin) by the action of a thiol protease from rat brain membranes. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. In isotope dilution experiments we find that the radioactivity from radiolabelled dynorphin B-29, which appears in dynorphin B during incubation with the enzyme preparation, is not diminished by addition of a high concentration of dynorphin B-Arg14. Moreover, in pulse-chase experiments, radioactivity that appeared in dynorphin B-Arg14 did not decrease, nor did the radioactivity in dynorphin B increase, after chasing with a high concentration of non-radioactive dynorphin B-29. These results indicate that although some dynorphin B-Arg14 is formed by the impure enzyme preparation, it is not an intermediate in the conversion of dynorphin B-29 to dynorphin B. Thus the formation of dynorphin B does not involve the action of a trypsin-like enzyme followed by removal of arginine-14 by a carboxypeptidase B-like enzyme. It appears that a single enzyme converts dynorphin B-29 to dynorphin B in a single step.

Topics: Animals; Brain; Cell Membrane; Chromatography, High Pressure Liquid; Cysteine Endopeptidases; Dynorphins; Endopeptidases; Endorphins; Enkephalins; Iodine Radioisotopes; Kinetics; Protein Precursors; Rats

Analysis of an acid extract of the striatum of the rhesus monkey revealed that the molar ratio of dynorphin A(1-8)-sized material and dynorphin (A(1-17)-sized material is approximately 1:1. In addition, the molar ratios of the dynorphin A-related end products to both dynorphin B(1-13)-sized material and alpha-neo-endorphin-sized material were approximately 1:1. Fractionation of an acid extract of the substantia nigra by gel filtration and reverse phase HPLC revealed the following molar ratios for pro-dynorphin-related end products. The molar ratio of dynorphin A(1-8) to dynorphin A(1-17) is approximately 6:1. The molar ratios of dynorphin A-related end products to dynorphin B(1-13) and alpha-neo-endorphin were approximately 0.5 and 0.8, respectively. Comparisons between proteolytic processing patterns of pro-dynorphin in the striatum and the substantia nigra of the rhesus monkey are considered. In addition, comparisons between pro-dynorphin processing in the substantia nigra of the rhesus monkey and the substantia nigra of the rat are discussed.

Topics: Animals; Chromatography, Gel; Chromatography, High Pressure Liquid; Corpus Striatum; Dynorphins; Endorphins; Enkephalins; Female; Macaca mulatta; Peptide Fragments; Protein Precursors; Radioimmunoassay; Substantia Nigra

The distribution of peptides derived from the novel opioid peptide precursor proenkephalin B (prodynorphin) was studied in lobes of the pituitary with antibodies against alpha-neoendorphin (alpha-neo-E) beta-neoE, dynorphin (DYN)-(1-17), DYN-(1-8), and DYN B in combination with gel filtration and high pressure liquid chromatography. In the posterior pituitary, all five opioid peptides occurred in high and about equimolar concentrations, whereas putative precursor peptides were found in only minor quantities. In contrast, in the anterior pituitary immunoreactive (ir-) DYN-(1-17) and ir-DYN B consisted exclusively of a common precursor species with a mol wt of about 6000. Six thousand-dalton DYN may be comprised of the C-terminal portion of proenkephalin B, with the sequence of DYN-(1-17) at its N-terminus. Moreover, the major portions of ir-alpha-neo-E and ir-beta-neoE in the anterior pituitary were found to be of an apparent mol wt of 8000. These findings indicate a differential processing of the opioid peptide precursor proenkephalin B in the two lobes of the pituitary. The anterior pituitary seems to process proenkephalin B predominantly into high mol wt forms of neo-E and DYNs, whereas in the posterior pituitary proenkephalin B undergoes further proteolytic processing to the smaller opioid peptides alpha-neo-E, beta-neo-E, DYN-(1-17), DYN-(1-8), and DYN B. Thus, processing differences may enable the selective liberation of different (opioid) peptides with distinct biological properties from one precursor within different tissues.

Topics: Animals; beta-Endorphin; Chromatography, High Pressure Liquid; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalins; Male; Molecular Weight; Peptide Fragments; Pituitary Gland; Pituitary Gland, Anterior; Pituitary Gland, Posterior; Protein Precursors; Radioimmunoassay; Rats; Rats, Inbred Strains; Tissue Distribution

The opioid activity and opioid receptor type specificity of synthetic human leumorphin were studied in vitro. Human leumorphin inhibited the contraction of the myenteric plexus-longitudinal muscle preparation of the guinea pig ileum and was similar in opioid potency to porcine leumorphin. This action of human leumorphin was antagonized less effectively by naloxone than by the opiate antagonist Mr 2266. Human leumorphin also inhibited the contraction of the rabbit vas deferens which has only the kappa-type opioid receptor. It is concluded that human leumorphin has potent opioid activity and acts as an agonist at the kappa-type opioid receptor, like porcine leumorphin and other peptides derived from preproenkephalin B.

Topics: Animals; Benzomorphans; Depression, Chemical; Dynorphins; Endorphins; Enkephalins; Guinea Pigs; Humans; Ileum; Male; Naloxone; Protein Precursors; Rabbits; Receptors, Opioid; Receptors, Opioid, kappa; Swine; Vas Deferens

The postnatal development of several pro-enkephalin-B-derived opioid peptides - dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha-neo-endorphin and beta-neo-endorphin - was examined in rat pituitary lobes. The concentrations of pro-enkephalin-B-derived peptides from the anterior pituitary were between 4- and 12-fold and those from the neurointermediate pituitary between 17- and 122-fold lower in newborn as compared to adult rats. Similarly, the concentrations of vasopressin in the neurointermediate pituitary increased 50-fold between birth and adulthood; those of oxytocin, however, increased more than 540-fold over this period. The molecular weight pattern of dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha- and beta-neo-endorphin-immunoreactive peptides in the anterior and neurointermediate pituitary did not differ between 3-day-old pups and adult rats. In the neurointermediate pituitary, the major immunoreactive components had the same chromatographic properties as synthetic dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha- and beta-neo-endorphin, respectively, on gel filtration and high-performance liquid chromatography (HPLC). This indicates that neonatal rats were already capable of processing the precursor pro-enkephalin B into these various opioid peptides. In newborn rats, however, the amount of dynorphin 1-8 in the neurointermediate pituitary was three times lower than that of its putative intermediate precursor peptide dynorphin 1-17. Similarly, the amount of beta-neo-endorphin was almost four times lower than that of its putative precursor alpha-neo-endorphin. In contrast, in the neurointermediate pituitary of adult rats, dynorphin 1-17 and dynorphin 1-8, in addition to a alpha- and beta-neo-endorphin, occurred in equimolar amounts.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Animals, Newborn; Cell Differentiation; Chromatography, High Pressure Liquid; Dynorphins; Endorphins; Enkephalin, Leucine; Enkephalins; Female; Male; Molecular Weight; Oxytocin; Peptide Fragments; Peptides; Pituitary Gland, Anterior; Pituitary Gland, Posterior; Pregnancy; Protein Precursors; Rats; Rats, Inbred Strains; Vasopressins

Leumorphin and rimorphin (dynorphin B) were nearly equipotent in inhibiting the contraction of the myenteric plexus-longitudinal muscle preparation of the guinea pig ileum and the rabbit vas deferens. Leumorphin had long duration of action in vitro after wash-out, whereas the duration of action of rimorphin was relatively shorter. These action of leumorphin and rimophin were antagonized less effectively by naloxone than by Mr2266, an antagonist relatively specific for the kappa-receptor. Rimorphin as well as leumorphin inhibits the contraction of the rabbit vas deferens which contains solely kappa-receptors. It is concluded that leumorphin and rimorphin have equipotent opioid activity and act at the kappa-receptor, like other opioid peptides derived from preproenkephalin B.

Topics: Animals; Biological Assay; Dynorphins; Electric Stimulation; Endorphins; Enkephalin, Leucine; Enkephalins; Guinea Pigs; Ileum; Male; Muscle Contraction; Muscle, Smooth; Naloxone; Protein Precursors; Rabbits; Receptors, Opioid; Receptors, Opioid, kappa; Vas Deferens

Using synthetic leumorphin, we obtained antisera for leumorphin and set up two radioimmunoassays (RIAs) with different specificities. Gel exclusion chromatography coupled with the two RIAs showed the existence of a considerable amount of leumorphin-like peptide in water extracts from porcine neuro-intermediate pituitaries. Reverse phase high performance liquid chromatography revealed that leumorphin-like peptide in the water extracts was indistinguishable from synthetic leumorphin. These results along with potent opioid activity of leumorphin indicate that leumorphin is a novel endogenous opioid peptide derived from preproenkephalin B.

Topics: Animals; Chemical Phenomena; Chemistry; Chromatography, Gel; Chromatography, High Pressure Liquid; Dynorphins; Electrophoresis, Polyacrylamide Gel; Endorphins; Enkephalin, Leucine; Enkephalins; Pituitary Gland; Protein Precursors; Radioimmunoassay; Swine