Effect of pertussis toxin on baclofen- and diphenhydramine-induced amnesia

The effect of pretreatment with pertussis toxin at the doses of 0.25 and 0.50 microg per mouse ICV on the amnesic effect produced by baclofen (0.1 4 mg kg(-1) i.p.), diphenhydramine (15-30 mg kg(-1) i.p.) and scopolamine (0.5-5 mg kg(-1) i.p.) was investigated in the mouse passive avoidance test. Ten days after a single injection of pertussis toxin, baclofen (2 4 mg kg(-1) i.p.) amnesia was prevented. By contrast, pertussis toxin had no effect on diphenhydramine- and scopolamine-induced amnesia. Pretreatment with pertussis toxin at both doses used did not impair motor coordination of the mice, as revealed by the rota-rod test. The present results indicate that the activation of pertussis toxin-sensitive G-proteins represents an important transduction step in memory impairment induced by GABA(B) (gamma-aminobutyric acid B) agonists, but not by antihistaminic and antimuscarinic drugs.