Abstract
Protein kinase C is a calcium- and phospholipid-stimulated enzyme present in high concentration in the brain. Phorbol esters are potent tumor promoters that bind to specific receptors with high affinity. Several lines of evidence indicate that the phorbol ester receptor is identical to protein kinase C. To determine the distribution of protein kinase C, we have localized phorbol ester receptors in the rat brain by autoradiography, using [3H]phorbol 12,13-dibutyrate ([3H]PDBu) and have performed a variety of lesions to assess the nature of the cellular elements possessing the binding sites. The [3H]PDBu binding sites in the rat brain are discretely localized and primarily associated with neurons. Evidence is presented for localization to intrinsic neurons of the cortex and hippocampus, terminals of the striatonigral projection, a projection to the molecular layer of the dentate gyrus, and to dendrites of Purkinje cells.