[Effects of oxiracetam on the decrease in population spikes in hypoxic and low glucose media].

Abstract

Evoked potentials were recorded in rat cerebral cortical slices. The amplitude of the evoked potential was reduced by perfusion with hypoxic (0-25%) or low glucose (0-5 mM) media in a concentration-dependent manner, and the evoked potentials disappeared under severe conditions (below 15% O2, below 3 mM glucose). We investigated the protective effects of oxiracetam on the decrease in evoked potentials under hypoxic (15% O2) and low glucose (3 mM glucose) conditions. Drugs were perfused from 45 min before hypoxic or low glucose perfusion to the end of the experiment. Oxiracetam (10(-6)-10(-5) M) dose-dependently minimized the amplitude reduction of evoked potentials and prolonged their disappearance time. At a concentration of 10(-5) M, oxiracetam protected against the disappearance of evoked potential in 5 of the 6 samples under hypoxic conditions and in all 6 samples under low glucose conditions. Indeloxazine (5 x 10(-6)-10(-5) M) and bifemelane (5 x 10(-6)-10(-5) M) prevented the reduction of the amplitude of evoked potentials under low glucose conditions. However, these drugs had no effect at a concentration of 10(-6) M. These data indicate that oxiracetam has a protective effect against neuronal dysfunction and that this effect develops at a lower concentration than those of indeloxazine and bifemelane.