POSTSYNAPTIC AND PRESYNAPTIC LESIONS IN THE CA1 REGION OF HIPPOCAMPUS - EFFECT ON [H-3] FORSKOLIN AND [H-3] PHORBOLDIBUTYRATE ESTER BINDING

The effect of transient cerebral ischemia and intraventricular injection of kainic acid on adenylate cyclase and protein kinase C as labeled by [H-3]forskolin ([H-3]FOR) and [H-3]phorboldibutyrate ester ([H-3]PDBU) in several rat brain microregions was investigated in a quantitative autoradiographic study. Four days after transient four vessel occlusion a 80% loss of [H-3]FOR and a 35% loss of [H-3]PDBU binding could be measured in the CA1 stratum radiatum of operated Wistar rats as compared to control rats. Four days after intraventricular injection of kainic acid only a marginal loss of [H-3]FOR and a 30% increase of [H-3]PDBU binding was seen in the CA1 stratum radiatum while in the CA3 stratum lucidum and radiatum respectively a 30% loss of [H-3]FOR and no significant change in [H-3]PDBU binding was observed. As transient cerebral ischemia and intraventricular kainic acid injection are depleting the hippocampal CA1 region of CA1 pyramidal cells and axons of CA3 pyramidal cells respectively in rat brain, these findings strongly suggest that both adenylate cyclase and protein kinase C are localized in CA1 pyramidal cells of rat hippocampus.