SEX-DIFFERENCES IN BICUCULLINE-INDUCED CONVULSIONS - INTERACTION WITHSTRESS AND LIGANDS OF BENZODIAZEPINE BINDING-SITES

The response to i.v. administration of bicuculline and its interaction with the benzodiazepine agonist diazepam and antagonist flumazenil we re studied in male and female handling stressed and swim stressed rats . Both handling stressed and swim stressed male rats needed less bicuc ulline to produce myoclonic twitch and running/bouncing (RB) clonus th an females. Besides, a lower dose of bicuculline produced tonic hindli mb extensor convulsion (THE) in male than in female swim stressed rats . Flumazenil failed to affect seizure thresholds for bicuculline eithe r in handling stressed or in swim stressed animals. Sex differences re mained present after diazepam pre-treatment as well. While diazepam en hanced doses of bicuculline producing all three convulsive signs simil arly in both handling and swim stressed rats (141-162%), swim stress h ad the lowest anticonvulsive effect for the onset of myoclonic twitch (110% in males and 117% in females) and the highest for THE (148% in m ales and 188% in females). The anticonvulsive effect of diazepam was n ot sex-dependent, while the anticonvulsive effect of swim stress was g reater in female than in male rats. The results suggest that greater s ensitivity of male rats to bicuculline and the anticonvulsive effect o f swim stress do not result from the release of endogenous modulators of benzodiazepine binding sites. (C) 1997 Elsevier Science B.V.