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

The e¤ect of pretreatment with pertussis toxin at the doses of 0.25 and 0.50 mg per mouse ICV on the amnesic e¤ect produced by baclofen (0.1 4 mg kg 1 IP), diphenhydramine (15 30 mg kg 1 IP) and scopolamine (0.5 5 mg kg 1 IP) was investigated in the mouse passive avoidance test. Ten days after a single injection of pertussis toxin, baclofen (2 4 mg kg 1 IP) amnesia was prevented. By contrast, pertussis toxin had no e¤ect on diphenhydramine- and scopolamineinduced 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 toxinsensitive G-proteins represents an important transduction step in memory impairment induced by GABAB (g-aminobutyric acid B) agonists, but not by antihistaminic and antimuscarinic drugs.