Enhanced resistance effect of piracetam upon hypoxia-induced impaired retention of fixed-interval responding in rats.

Rats were trained on a fixed-interval schedule of 60 s (FI 60). After stabilization of performance, rats were chronically submitted to hypoxic treatment (3.5% O2, 10 min) once a day, immediately after the daily FI 60 session. Hypoxia disturbed the retention of FI responding. It was mainly characterized by a decrease in response rate and in pause duration, and by changes in the temporal distribution of responses. Animals receiving piracetam (100 mg/kg, IP) 30 min before each FI session followed by hypoxia were significantly less affected than saline-treated animals. Results are discussed with reference to the effects of hypoxia and piracetam on nonspecific factors and on memory function. It is suggested that the effects of piracetam are due to alleviation of hypoxia-induced memory retrieval deficit rather than to a protection against hypoxic brain cell injury.