Partial reversal of behavioral action of the agonist D-Trp-6-LH-RH by naloxone in mice.
The effects of the superactive agonist analog D-Trp-6-LH-RH were investigated in several neuropharmacological tests: inhibition of picrotoxin-induced seizures, open-field behavior, hot-plate and tail-flick tests, assessment of catalepsy and apomorphine-induced cage-climbing. In most tests, D-Trp-6-LH-RH was administered subcutaneously (sc.) at the dose of 100 micrograms/kg. The opiate involvement in the peptide action was checked by using naloxone HCl (NX) in a dose of 1 mg/kg intraperitoneally (ip.), with the exception of the analgesic tests where the dose was 0.5 mg/kg. The analog significantly suppressed the open-field parameters of ambulation, rearing and grooming; except for grooming, these actions were fully antagonized by NX. Similarly, NX pretreatment restored to the control levels the latencies of seizure parameters increased by D-Trp-6-LH-RH. The hot-plate latencies did not change after pretreatment with NX but the opiate antagonist was fully able to antagonize the analgesic effect of the peptide in the tail-flick test. The cataleptogenic effect and the inhibition of apomorphine-induced cage-climbing demonstrated after D-Trp-LH-RH were not antagonized by NX.
Kádár
T
T
Department of Pathophysiology, A. Szent-Györgyi Medical University, Szeged, Hungary.
Telegdy
G
G
Schally
A V
AV
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006120:Grooming / Q000187:drug effects; D008186:Luteolytic Agents / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D017329:Triptorelin Pamoate
D000927:Anticonvulsants; D008186:Luteolytic Agents; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; D009270:Naloxone