LONG-TERM CHANGES IN GERBIL BRAIN NEUROTRANSMITTER RECEPTORS FOLLOWING TRANSIENT CEREBRAL-ISCHEMIA

1 Receptor autoradiographic and histological techniques were used to investigate long-term changes in the gerbil brain following transient cerebral ischaemia. 2 Transient ischaemia was induced for 3 min and 10 min, and the animals were allowed to survive for 8 months. 3 Histological examination revealed that 3 min ischaemia caused neuronal damage and mild shrinkage only in the hippocampal CA1 sector. Ten minutes of ischaemia produced severe neuronal damage in the striatum and the hippocampal CA1 and CA3 sectors. Considerable shrinkage was seen in the hippocampus; the dentate gyrus, however, was not damaged. 4 Three minutes of ischaemia produced changes in the binding of [H-3]-quinuclidinylbenzilate ([H-3]-QNB), [H-3]-muscimol, and [H-3]-MK-801 in various brain regions, as determined autoradiographically. In contrast, [H-3]-cyclohexyladenosine ([H-3]-CHA) and [H-3]-PN200-110 ([H-3]-isradipine) binding in the brain was unaltered. 5 Ten minutes of ischaemia resulted in a major loss of neurotransmitter receptors, especially in the hippocampus. The substantia nigra showed a significant reduction in [H-3]-CHA binding, whereas the striatum, which was morphologically damaged, showed no significant changes in any of the neurotransmitter receptors examined. 6 The results demonstrated that long-term survival after transient cerebral ischaemia produced alterations in neurotransmitter receptors, especially in the hippocampal formation, where considerable shrinkage was noted. These results also suggest that the hippocampal damage was not static, but progressive.