NMDA component in the effects of piracetam and new nootropic peptide GVS-111 on the neocortical and hippocampal EEG in conscious rats

Abstract

The effects of new nootropic dipeptide GVS-111 (N-phenylacetyl-L-prolylglycine ethyl ester) on EEG spectral characteristics were compared with those of piracetam. The EEG was recorded in the cortex and hippocampus of nonanesthetized nonrestrained rats with chronically implanted electrodes. GVS-111 and piracetam induced similar changes in EEG spectral profile in both structures increasing the o~-band power and decreasing the power of the 13-and 6-bands. These effects were prevented by intracerebral injection of 10 -~~ mol NMDA receptor antagonist (• acid. The data correlate with behavioral and neurochemical findings and suggest that NMDA receptors can be specifically involved in the mechanisms of nootropic effects of piracetam and GVS-111. In this study we compared the effects of GVS-111 and piracetam on spectral characteristics of EEG in the cortex and hippocampus of free-moving rats and assessed the involvement of NMDA receptors in these effects. The choice of these two structures was determined by the data on cortical and subcortical effects of nootropic drugs [2]. MATERIALS AND METHODSExperiments were carried out on 8 conscious fleemoving male Wistar rats weighing 350-420 g. Nichrome electrodes (0.4 mm in diameter) were implanted in the symmetrical areas of the somatosensory cortex and dorsal hippocampus (CA 1 area) of the right hemisphere under Nembutal anesthesia (50 mg/kg, subcutaneously). A cannula was implanted in the right lateral ventricle using a modified Meshcherski stereotaxic apparatus according to the rat brain atlas coordinates [11] AP=-0.4, L=3.2, H=3.7, ~=20, where o~ is the angle between the sagittal plane and the cannula.