The effect of naloxone on cerebellar cGMP content. A possible GABA-antagonistic action?
Naloxone in high doses (60--240 mg/kg i.p.) produced a dose-dependent increase in cerebellar cGMP content of mice. The rise in cGMP content reached its maximum within 5 min and was of short duration. Short-lasting episodes of clonic seizures were noted after 240 mg/kg naloxone. Low doses of naloxone (5--10 mg/kg) had no effect on cerebellar cGMP content, but markedly potentiated the increase in cGMP induced by isoniazid. On the other hand, naloxone (5 mg/kg) partially antagonized the fall in cGMP elicited by diazepam, but had only a slight effect on the action of pentobarbital (30 mg/kg i.p.). These results support the assumption proposed by other authors that naloxone exerts GABA antagonistic effects aside from the potent opiate receptor antagonistic activity.
D000818:Animals; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D003975:Diazepam / Q000494:pharmacology; D018756:GABA Antagonists; D007538:Isoniazid / Q000494:pharmacology; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology*; D010424:Pentobarbital / Q000494:pharmacology; D013997:Time Factors
D018756:GABA Antagonists; D009270:Naloxone; D006152:Cyclic GMP; D010424:Pentobarbital; D003975:Diazepam; D007538:Isoniazid