EFFECT OF PERTUSSIS TOXIN ON BACLOFEN-INDUCED AND DIPHENHYDRAMINE-INDUCED AMNESIA

The effect of pretreatment with pertussis toxin at the doses of 0.25 a nd 0.50 mu g per mouse ICV on the amnesic effect produced by baclofen (0.1-4 mg kg(-1) IP), diphenhydramine (15-30 mg kg(-1) IP) and scopola mine (0.5-5 mg kg(-1) IP) was investigated in the mouse passive avoida nce test. Ten days after a single injection of pertussis toxin, baclof en (2-4 mg kg(-1) IP) amnesia was prevented. By contrast, pertussis to xin had no effect on diphenhydramine-and scopolamine-induced amnesia. Pretreatment with pertussis toxin at both doses used did not impair mo tor coordination of the mice,as revealed by the rota-rod test. The pre sent results indicate that the activation of pertussis toxin-sensitive G-proteins represents an important transduction step in memory impair ment induced by GABA(B) (gamma-aminobutyric acid B) agonists, but not by antihistaminic and antimuscarinic drugs.