[CAS NO. 7491-74-9]  Piracetam

Piracetam (300 mg/kg once daily) significantly increases membrane fluidity in some brain regions of young and aged rats, but has no measurable effect on membrane fluidity in the young rats. Piracetam (300 mg/kg daily for 6 weeks) improves active avoidance learning in the aged rats only and elevates membrane fluidity in all brain regions except the cerebellum in the aged rats. Piracetam (300 mg/kg daily for 6 weeks) also improves NMDA receptor density in the hippocampus and on muscarinic cholinergic receptor densities in the frontal cortex and the striatum and to a lesser extent in the hippocampus of rats. Piracetam (500 mg/kg p.o. for 14 days) elevates N-methyl-D-aspartate (NMDA) receptor density by about 20% and normalizes the enhanced affinity of L-glutamate for the NMDA receptor in aged mice. Piracetam-treated withdrawn rats has higher the number of synapses than that observed in nonpiracetam-treated and alcohol-fed animals by up to 20%, the mechanisms leading to the synaptic reorganization took place at the mossy fiber level.