Morphine withdrawal precipitated by specific mu, delta or kappa opioid receptor antagonists: a c-Fos protein study in the rat central nervous system

摘要: We have recently shown concurrent changes in behavioural responses and c-Fos protein expression the central nervous system both naive morphine-dependent rats after systemic administration of opioid antagonist naloxone. However, because naloxone acts on three major types receptors, present study aimed at determining, same animals, behaviour c-Fos-like immunoreactivity intravenous injection selective antagonists, such as mu (beta-funaltrexamine, 10 mg/kg), delta (naltrindole, 4 mg/kg) or kappa (nor-binaltorphimine, 5 receptor rats. In a first experimental series, only beta-funaltrexamine increased eight structures examined, whereas no effect was seen naltrindole nor-binaltorphimine These results suggest tonic activity endogenous peptides acting receptors normal A second series showed that had highest potency induction classical signs morphine withdrawal syndrome, well increase 22 studied, suggesting role dependence. our also demonstrated and, to lesser extent, were able induce moderate relatively weak restricted structures. Therefore, may contribute slightly