[Effects of piracetam and meclofenoxate on the brain NMDA and nicotinic receptors in mice with different exploratory efficacy in the cross maze test].

A population of outbred mice of the ICR strain was divided into two subpopulations according to their high (EH mice) or low (EL mice) exploratory efficacy in the closed cross maze test. In addition, the EH and EL mice differed in the number of binding sites of (i) [G-3H]-MK-801 with NMDA receptors from hippocampus and (ii) [G-3H]-nicotine with nicotine cholinoreceptors (nACh) from neocortex. A subchronic administration of the cognition enhancer piracetam (200 mg/kg, once per day for 5 days) increased by 70% the number of binding sites of NMDA receptors in the EL mice. At the same time, this treatment decreased the density of neocortical nACh receptors in both EL and EH mice (by 55% and 40%, respectively). A subchronic administration of the cognition enhancer and anti-oxidant meclofenoxate (100 mg/kg, once per day for 5 days) also decreased the density of neocortical nACh receptors in both EL and EH mice (by 48% and 20%, respectively). However, meclofenoxate also increased by 41% the number of binding sites of NMDA receptors in the EH mice.