Visualization of the Distribution of Autophosphorylated Calcium/ Calmodulin-Dependent Protein Kinase II after Tetanic Stimulation in the CA1 Area of the Hippocampus

Autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) at threonine-286 produces Ca21-independent kinase activity and has been proposed to be involved in induction of long-term potentiation by tetanic stim-ulation in the hippocampus. We have used an immunocyto-chemical method to visualize and quantify the pattern of auto-phosphorylation of CaMKII in hippocampal slices after tetanization of the Schaffer collateral pathway. Thirty minutes after tetanic stimulation, autophosphorylated CaM kinase II (P-CaMKII) is significantly increased in area CA1 both in apical dendrites and in pyramidal cell somas. In apical dendrites, this increase is accompanied by an equally significant increase in staining for nonphosphorylated CaM kinase II. Thus, the in-crease in P-CaMKII appears to be secondary to an increase in the total amount of CaMKII. In neuronal somas, however, th