Effects of oxiracetam-nicotine combinations on active and passive avoidance learning in mice.

Tested alone, in CD-1 mice, the nootropic drug oxiracetam (50 mg/kg) improved learning in a multitrial active avoidance task (shuttle-box), but did not affect one-trial passive avoidance acquisition. Nicotine, which was ineffective at the dose of 0.25 mg/kg, improved both active and passive avoidance at the dose of 0.5 mg/kg; 1 mg/kg nicotine still exerted facilitating effects on passive avoidance, but slightly depressed shuttle-box performance. Combinations of oxiracetam and nicotine improved passive avoidance more than either drug given separately. In the active avoidance task, a combination of oxiracetam with the lower dose of nicotine exerted improving effects never observed with nicotine alone, even at higher doses. The nootropic drug also prevented the slight depressant action exerted by 1 mg/kg nicotine. Thus, contrary to what was previously supposed, at least in mice subjected to shuttle-box avoidance training, nicotinic activation does not appear as the main neurochemical mechanism involved in the action of oxiracetam. Perhaps, oxiracetam and nicotine activate different types of cholinergic mechanisms, but it cannot be excluded that other neurotransmitters, particularly catecholamines, may be involved in the avoidance facilitating effects produced by nicotine and by combinations of the two drugs.