naloxone and binaltorphimine

The participation of the peripheral opioid and cannabinoid endogenous systems in modulating muscle pain and inflammation has not been fully explored. Thus, the aim of this study was to investigate the involvement of these endogenous systems during muscular-tissue hyperalgesia induced by inflammation. Hyperalgesia was induced by carrageenan injection into the tibialis anterior muscles of male Wistar rats. We padronized an available Randal-Sellito test adaptation to evaluate nociceptive behavior elicited by mechanical insult in muscles. Western blot analysis was performed to evaluate the expression levels of opioid and cannabinoid receptors in the dorsal root ganglia. The non-selective opioid peptide receptor antagonist (naloxone) and the selective mu opioid receptor MOP (clocinnamox) and kappa opioid receptor KOP (nor-binaltorphimine) antagonists were able to intensify carrageenan-induced muscular hyperalgesia. On the other hand, the selective delta opioid receptor (DOP) antagonist (naltrindole) did not present any effect on nociceptive behavior. Moreover, the selective inhibitor of aminopeptidases (Bestatin) provoked considerable dose-dependent analgesia when intramuscularly injected into the hyperalgesic muscle. The CB

Topics: Animals; Arachidonic Acids; Carrageenan; Cinnamates; Endocannabinoids; Hyperalgesia; Male; Monoacylglycerol Lipases; Morphine Derivatives; Myalgia; Naloxone; Naltrexone; Pain Measurement; Polyunsaturated Alkamides; Rats; Rats, Wistar; Receptors, Cannabinoid; Receptors, Opioid; Receptors, Opioid, delta; Receptors, Opioid, kappa; Receptors, Opioid, mu

Previously, we reported that central administration of bombesin, a stress-related peptide, elevated plasma levels of catecholamines (noradrenaline and adrenaline) in the rat. The sympatho-adrenomedullary system, which is an important component of stress responses, can be regulated by the central opioid system. In the present study, therefore, we examined the roles of brain opioid receptor subtypes (µ, δ, and κ) and nociceptin receptors, originally identified as opioid-like orphan receptors, in the bombesin-induced activation of central sympatho-adrenomedullary outflow using anesthetized male Wistar rats. Intracerebroventricularly (i.c.v.) administered bombesin-(1 nmol/animal) induced elevation of plasma catecholamines was significantly potentiated by pretreatment with naloxone (300 and 1000 µg/animal, i.c.v.), a non-selective antagonist for µ-, δ-, and κ-opioid receptors. Pretreatment with cyprodime (100 µg/animal, i.c.v.), a selective antagonist for µ-opioid receptors, also potentiated the bombesin-induced responses. In contrast, pretreatment with naltrindole (100 µg/animal, i.c.v.) or nor-binaltorphimine (100 µg/animal, i.c.v.), a selective antagonist for δ- or κ-opioid receptors, significantly reduced the elevation of bombesin-induced catecholamines. In addition, pretreatment with JTC-801 (30 and 100 µg/animal, i.c.v.) or J-113397 (100 µg/animal, i.c.v.), which are selective antagonists for nociceptin receptors, also reduced the bombesin-induced responses. These results suggest that brain µ-opioid receptors play a suppressive role and that brain δ-, κ-opioid, and nociceptin receptors play a facilitative role in the bombesin-induced elevation of plasma catecholamines in the rat. Thus, in the brain, these receptors could play differential roles in regulating the activation of central sympatho-adrenomedullary outflow.

Topics: Adrenal Medulla; Animals; Bombesin; Brain; Catecholamines; Morphinans; Naloxone; Naltrexone; Nociceptin Receptor; Rats; Receptors, Opioid; Sympathetic Nervous System

Rat fetuses can perceive chemosensory stimuli derived from their mother's diet, and they may learn about those stimuli. In previous studies we have observed that prenatal exposure to alcohol during the last days of gestation increases the acceptance and liking of an alcohol flavor in infant and adolescent rats. While these results were not found after prenatal exposure to vanilla, cineole or anise, suggesting that the pharmacological properties of alcohol, mediated by the opioid system, underlie the effects observed with this drug. Considering that other studies report enhanced acceptance of non-alcohol flavors experienced prenatally when subjects were tested before infancy, we explore the possibility of observing similar results if testing 1-day old rats exposed prenatally to vanilla. Using an "odor-induced crawling" testing procedure, it was observed that neonates exposed prenatally to vanilla or alcohol crawl for a longer distance towards the experienced odor than to other odors or than control pups. Blocking mu, but not kappa opioid receptors, reduced the attraction of vanilla odor to neonates exposed to vanilla in utero, while the response to alcohol in pups exposed prenatally to this drug was affected by both antagonists. Results confirm that exposure to a non-alcohol odor enhances postnatal responses to it, observable soon after birth, while also suggesting that the mu opioid receptor system plays an important role in generating this effect. The results also imply that with alcohol exposure, the prenatal opioid system is wholly involved, which could explain the longer retention of the enhanced attraction to alcohol following prenatal experience with the drug.

Topics: Analysis of Variance; Animals; Animals, Newborn; Drug-Seeking Behavior; Ethanol; Female; Locomotion; Maternal Exposure; Naloxone; Naltrexone; Odorants; Pregnancy; Rats; Rats, Sprague-Dawley; Receptors, Opioid; Vanilla

In a model of self-sustaining status epilepticus induced in rats by 30 min intermittent stimulation of the perforant path through chronically implanted electrodes, a decrease in dynorphin-like immunoreactivity in the dentate gyrus and CA3 was observed 3 h and 24 h after the induction of status epilepticus. Enkephalin-like immunoreactivity decreased 3 h but not 24 h after perforant path stimulation. Injection into the hilus of the dentate gyrus 10 min prior to stimulation of the kappa-receptor agonist dynorphin-A(1-13), the delta-receptor antagonists ICI-174864 and naltrindole, as well as i.p. injection of naloxone prevented the development of status epilepticus. Perihilar administration of the delta-agonist [D-Ser2]Leu-enkephalin-Thr6 or the kappa-antagonist nor-Binaltorphimine, but not of the mu-agonist [D-Ala2,N-Me-Phe4,Gly-ol5]-Enkephalin, facilitated the establishment of self-sustaining status epilepticus. Injection into the hilus of dynorphin-A(1-13) after the end of perforant path stimulation, stopped established status epilepticus, while administration of naloxone, naltrindole and ICI-174864 were ineffective. We conclude that kappa-opioids in the hippocampus counteract initiation and maintenance of status epilepticus, while delta-opioids promote initiation, but not maintenance of seizure activity. These data are important for the understanding the mechanisms which underlie initiation and maintenance of status epilepticus and for the development of new approaches for its effective management.

Topics: Action Potentials; Analgesics; Analgesics, Opioid; Animals; Disease Models, Animal; Dynorphins; Electric Stimulation; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalin, Leucine; Enkephalins; Immunohistochemistry; Male; Naloxone; Naltrexone; Narcotic Antagonists; Neurons; Opioid Peptides; Peptide Fragments; Perforant Pathway; Rats; Rats, Wistar; Receptors, Opioid, delta; Receptors, Opioid, kappa; Status Epilepticus

The head kidney is the main lymphopoietic organ of teleost fish. It is the source of leukocytes inhabiting the peritoneal cavity during an experimental peritoneal inflammation (Gruca et al., Folia Biol.-Kraków, 1997, 44, 137-142). The number of elicited peritoneal leukocytes is significantly lower in the goldfish with concomitant morphine injection than in their counterparts injected with the irritant only. Morphine may act directly on the head kidney leukocytes, as they are equipped with the selective naloxone-binding sites (Chadzińska et al., Arch. Immunol. Ther. Exp., 1997, in press). Further characterization of these opioid receptors (by radioligand binding techniques) indicates that the goldfish head kidney leukocytes possess at least two different opiate-binding sites: the [3H]naloxone binding site with a KD = 87 +/- 2.1 nM and Bmax = 298 +/- 15 fmol/mg protein; and the second, the [3H]naltrindole binding site with a KD = 37 +/- 5.5 nM and Bmax = 1,172 +/- 220 fmol/mg protein. The competition experiments with delta- (naltrindole), kappa- (nor-binaltorphimine) and mu- (cyprodime, naltrexone) selective ligands suggest that the naloxone-binding site is similar to mu 3 receptors described by Stefano et al. (Proc. Nat. Acad. Sci. USA, 1993, 90 11099-11103). Low affinity binding of selective ligands excludes the presence of neuronal-type mu- and delta-opioid receptors on goldfish leukocytes.

Topics: Animals; Binding Sites; Goldfish; Leukocytes; Morphinans; Morphine; Naloxone; Naltrexone; Narcotic Antagonists; Receptors, Opioid, delta; Receptors, Opioid, mu

Topics: Animals; Cells, Cultured; Diabetic Neuropathies; Ganglia, Spinal; Naloxone; Naltrexone; Nerve Growth Factors; Paclitaxel

We previously reported that kappa opioids stimulated the release of human placental lactogen (hPL) from trophoblastic cells and that this effect was prevented by co-incubation with naloxone. We also reported that adenylate cyclase was not directly involved in this process. In order to understand the post-receptor events mediating hPL release by opioids in the human placenta, we studied the role of extracellular calcium. Human trophoblastic cells obtained by trypsin digestion were cultured for 48 h in Ham's F-10 medium supplemented with 10% fetal bovine serum (FBS), 200 U/ml penicillin, and 200 micrograms/ml streptomycin. 45Ca2+ influx was then measured by filtration on glass-fiber filters. We observed a time- and dose-dependent stimulation of 45Ca2+ influx by ethylketocyclazocine (EKC) with an EC50 of 0.5 nM and a maximal stimulation of 196% over control. This effect was completely blocked by naloxone, a non-specific opioid antagonist, and by nor-binaltorphimine, a specific kappa antagonist. We also demonstrated that U-50,488 (kappa agonist) had the same stimulatory effect as EKC (221 +/- 25% of control). D-Ala2,NMe-Phe4,Gly-ol5)-enkephalin (DAGO) (mu agonist) slightly stimulated Ca2+ influx (128 +/- 5% of control, p > 0.05) whereas D-Ser2,Leu,Thr6)-enkephalin (DSLET) (delta agonist) had no effect. Pre-incubation of trophoblastic cells with pertussis toxin (PTX) did not affect the EKC-induced 45Ca2+ influx, suggesting that this placental opiate effect is not coupled with PTX-sensitive G proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Adenylate Cyclase Toxin; Analgesics; Calcium; Cells, Cultured; Dopamine; Dose-Response Relationship, Drug; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalin, Leucine; Enkephalins; Ethylketocyclazocine; Gene Expression Regulation; Humans; Ionomycin; Naloxone; Naltrexone; Narcotics; Pertussis Toxin; Placental Lactogen; Pyrrolidines; Time Factors; Trophoblasts; Virulence Factors, Bordetella

The present study was undertaken to determine whether acute physical dependence occurred in guinea-pigs in vivo and guinea-pig isolated ileum following a single dose of the kappa-opioid receptor agonist U50,488H. Administration of naloxone hydrochloride, 15 and 30 mg/kg s.c., to guinea-pigs treated 1 h before with U50,488H, 10 mg/kg s.c., induced increased locomotor activity accompanied by behavioural responses which differed from those previously found in this species with morphine withdrawal. Nor-binaltorphimine, 10 mg/kg s.c., given 1 h after administration of U50,488H, 10 mg/kg s.c., produced a small but significant increase in locomotor activity but no other withdrawal behaviours. The morphine withdrawal response was not significantly affected by U50,488H, 1 or 10 mg/kg s.c. On the guinea-pig isolated ileum, nor-binaltorphimine, 1 microM, produced a withdrawal contracture following 2 min contact of the ileum with U50,488H 1 microM. U50,488H, 1 microM, abolished the [Met5]enkephalin withdrawal response of the ileum. It is concluded that dependence occurs following activation of kappa-opioid receptors, which is largely non-morphine-like in the central nervous system, but which is morphine-like in the enteric nervous system.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Opioid; Animals; Behavior, Animal; Female; Guinea Pigs; Ileum; In Vitro Techniques; Male; Morphine Dependence; Motor Activity; Muscle Contraction; Muscle, Smooth; Naloxone; Naltrexone; Pyrrolidines; Receptors, Opioid, kappa; Substance Withdrawal Syndrome; Substance-Related Disorders

Tail-pinch feeding (TPF) in rats is decreased following general (naltrexone, NTX) and mu (Cys2-Tyr3-Orn5-Pen7-amide, CTOP) opioid antagonists, but not following kappa (nor-binaltorphamine. Nor-BNI) or delta (naltrindole, NTI) opioid antagonists. Because multiple mu (mu1 and mu2) and delta (delta 1 and delta 2) opioid receptor subtypes have been characterized, the present study evaluated whether TPF was differentially altered following ICV administration of general (NTX), mu (beta-funaltrexamine, B-FNA), mu1 (naloxonazine, NAZ), kappa (Nor-BNI), delta 1 ([D-Ala2, Leu5, Cys6]-enkephalin, DALCE) and delta 2 (NTI) opioid antagonists. Like the reversible mu antagonist CTOP, the irreversible mu antagonist B-FNA significantly and dose-dependently (1-20 micrograms) reduced TPF by up to 28%. In contrast, whereas NAZ (50 micrograms) reduced TPF by 32%, this effect was highly variable and failed to achieve significance. Neither NTX (5-10 mg/kg, SC), Nor-BNI (20 micrograms), DALCE (40 micrograms) nor NTI (20 micrograms) significantly altered TPF, suggesting that kappa, delta 1 and delta 2 opioid receptor subtypes were not involved. Because no antagonist altered the duration of food contact during tail pinch, it appears that the opioid effect modulates ingestive rather than activational mechanisms. The reliable inhibition of TPF by B-FNA (mu1 and mu2), together with the variable effect of naloxonazine (mu1), appears to implicate both mu binding sites in this response.

Topics: Animals; Arousal; Enkephalin, Leucine-2-Alanine; Feeding Behavior; Indoles; Male; Morphinans; Naloxone; Naltrexone; Narcotic Antagonists; Nociceptors; Rats; Rats, Sprague-Dawley; Receptors, Opioid, mu

A series of experiments provided evidence for the existence of a functional opioid system in the fetal rat near term. Application of a tactile probe to the perioral region of the fetus consistently evoked a stereotypic facial wiping response. Administration of low dosages of morphine to the fetus had little effect on nonevoked motor activity but reduced fetal responsiveness to cutaneous stimulation. Milk infused into the mouth of the fetus reduced fetal responsiveness to the tactile probe. Milk's effect on cutaneous responsiveness was reversed by injection of the nonspecific opioid antagonist naloxone. The effect of milk on fetal responsiveness to cutaneous stimulation was reversed by the kappa opioid antagonist nor-binaltorphimine, but not by the mu antagonist beta-funaltrexamine. Milk engages the endogenous opioid system of the fetal rat and affects fetal responsiveness by interacting with the kappa receptors of the opioid system.

Topics: Aging; Animals; Arousal; Chemoreceptor Cells; Dose-Response Relationship, Drug; Female; Fetal Movement; Gestational Age; Morphine; Motor Activity; Naloxone; Naltrexone; Pregnancy; Rats; Receptors, Opioid; Receptors, Opioid, kappa; Sucking Behavior; Taste; Touch

Daily rhythms of secretion have been described for luteinizing hormone (LH) and prolactin (PRL) from the anterior pituitary of rats. Using selective opioid antagonists, we found that mu and kappa opioid receptor ligands regulate LH and PRL secretion and, of particular interest, that the magnitude of opioidergic effects varies with the time of day. In addition, incomplete temporal overlapping of the LH and PRL responses to the antagonists suggests that different endogenous opioid pathways, with different temporal profiles of peptide release, may control each of these hormones.

Topics: Animals; Circadian Rhythm; Dose-Response Relationship, Drug; Endorphins; Ligands; Luteinizing Hormone; Male; Naloxone; Naltrexone; Pituitary Gland, Anterior; Prolactin; Rats; Rats, Inbred Strains; Receptors, Opioid

The opioid antagonist activities of two bivalent ligands, BNI and nor-BNI, have been evaluated in smooth muscle preparations and in mice. Both ligands are highly potent and selective as kappa opioid receptor antagonists, with relatively feeble blocking activity at mu and delta opioid receptors. BNI and nor-BNI represent the first highly selective kappa opioid receptor antagonists and should be of great utility as molecular probes for identifying the interaction of agonist ligands with kappa opioid receptors in vitro and in vivo.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Chemical Phenomena; Chemistry; Cyclazocine; Dynorphins; Enkephalin, Leucine; Enkephalin, Leucine-2-Alanine; Ethylketocyclazocine; Guinea Pigs; Male; Mice; Morphine; Naloxone; Naltrexone; Pyrrolidines; Rabbits; Receptors, Opioid; Receptors, Opioid, kappa