Piracetam improves cognitive performance by restoring neurochemical deficits of the aged rat brain

In order to test the hypothesis that piracetam improves cognitive functions by restoring biochemical deficits of the aging brain, we investigated the effects of piracetam treatment (300 mg/kg daily for 6 weeks) on the active avoidance performance of young and aged rats. After testing, the rats were killed and membrane fluidity and NMDA as well muscarinic cholinergic recept or densities were determined in the frontal cortex, the hippocampus, the st riatum, as well as the cerebellum. Piracetam treatment improved active avoi dance learning in the aged rats only and elevated membrane fluidity in all brain regions except the cerebellum in the aged animals. Moreover, we obser ved a positive effect of piracetam treatment on NMDA receptor density in th e hippocampus and on muscarinic cholinergic receptor densities in the front al cortex and the striatum and to a lesser extent in the hippocampus. Again , these effects were only observed in aged animals. Discrimination analysis indicated that piracetam effects on membrane fluidity in the frontal corte x, the hippocampus, and the striatum and its effects on NMDA densities in t he hippocampus might be involved in its positive effects on cognitive perfo rmance.