ACUTE ISCHEMIC VULNERABILITY OF PKA IN THE DENDRITIC SUBFIELDS OF THEHIPPOCAMPUS CA1

ALTERATIONS of [H-3]cyclic AMP (cAMP) binding, an indicator of the bin ding activity of particulate cyclic AMP-dependent protein kinase (PKA) , were examined after 15 and 30 min of ischemia in the gerbil brain. S evere hemispheric cerebral ischemia was induced by occluding the right common carotid artery. Significant reductions in cAMP binding were no ted only in the dendritic subfields of the hippocampus CA1 such as the strata oriens, radiatum and lacunosum-moleculare, on the ischemic sid e after 15 min of ischemia. After 30 min ischemia cAMP binding was sig nificantly decreased not only in each dendritic subfield of the hippoc ampus CA1, but also in the layer of pyramidal cell bodies (stratum pyr amidale) on the occluded side; other brain regions such as the hippoca mpus CA3, dentate gyrus and cerebral cortices revealed no significant changes in cAMP binding. These findings suggest that derangement of PK A may begin in the dendritic subfields of the hippocampus CA1 after as little as 15 min of severe ischemia, and proceed centrally to the neu ronal cell bodies of the hippocampus CA1.