Neuroprotective efficiency of NMDA receptor blockade in the striatum and CA3 hippocampus after various durations of cerebral ischemia in gerbils.

The purpose of this study was to investigate neuroprotective efficiency of N-methyl D-aspartate (NMDA) receptor (NMDAR) blockade on the neuronal damage in the less studied and allegedly less affected CA3 hippocampus and striatum in the Mongolian gerbil model of global cerebral ischemia. The common carotid arteries of gerbils were occluded for 5, 10 or 15 minutes. Gerbils were given a low dose of non-competitive NMDA antagonist (MK-801, 3 mg/kg i.p.) or saline immediately after the occlusion in normothermic conditions. Neuronal damage was examined on 4th, 14th and 28th day after reperfusion. The effect of NMDAR blockade was followed in vivo by monitoring the neurological status of whole animals or at the cellular level by standard light- and confocal microscopy on brain slices. Increased duration of cerebral ischemia resulted in a progressive loss of striatal and CA3 hippocampal neurons. The most beneficial NMDAR blockade effect was observed when the neuronal damage was most severe - on the 28th day after 15-min ischemia. As judged by morphological and neurological data, the effect of ischemia is also apparent in the presumed less vulnerable regions (CA3 and striatum) which are functionally important in stroke plasticity. So, NMDAR blockade in normothermic conditions showed neuroprotective efficiency.