Determinants of survival after forebrain ischemia in Mongolian gerbils.

Mongolian gerbils were exposed to 15 min of cerebral ischemia. Quantitative histology was used to establish neuronal damage in the CA1, CA2/3, and CA3 sectors of the hippocampus 2 weeks after the insult. Seven moribund animals were sacrificed earlier to examine whether there is a correlation between hippocampal damage and mortality. Surviving animals had a 86.6% loss of CA1 neurons. In the CA2/3 and CA3 sectors 62.7 and 72.6% of the neurons were preserved. Moribund animals had a further dramatic loss of nerve cells in these sectors, to 14.8 and 20.3%, respectively. The reduction of CA2/3 neurons and survival time were correlated. In addition, gerbils which would later become moribund were found to have a significant increase in plasma osmolarity from 319 to 342 mosm/liter and of hematocrit from 47.4 to 53.9 at day 4 after ischemia.