Imaging of memory-specific changes in the distribution of protein kinase C in the hippocampus

Activation of protein kinase C (PKC) can mimic the biophysical effects of associative learning on neurons. Furthermore, classical conditioning of the rabbit nictitating membrane (a form of associative learning) produces translocation of PKC activity from the cytosolic to the membrane compartments of the CA1 region of the hippocampus. Evidence is provided here for a significant change in the amount and distribution of PKC within the CA1 cell field of the rabbit hippocampus that is specific to learning. This change is seen at 1 day after learning as focal increments of [3H]phorbol-12,13-dibutyrate binding to PKC in computer-generated images produced from coronal autoradiographs of rabbit brain. In addition, 3 days after learning, the autoradiographs suggest a redistribution of PKC within CA1 from the cell soma to the dendrites.