Immunocytochemical staining with antibodies against protein kinase C and its isozymes in the turtle retina

Summary An LM immunocytochemical study has investigated the patterns of staining in turtle retina with monoclonal antibodies to the , and isozymes of protein kinase C. The protein kinase C- antibody reveals cells in the ganglion cell layer, occasional amacrine cells and faint banding in strata 2 and 4 of the inner plexiform layer. The protein kinase C- antibody stains primarily amacrine cells that have dendrites running in strata 2, in 4 close to the 3/4 border and on the 4/5 border of the inner plexiform layer. Protein kinase C- immunoreactivity is seen in a population of bipolar cells. The latter are characterized by stained axon terminals in strata 3 and 4 of the inner plexiform layer. A type of amacrine cell, different from those seen with the other antibodies, is also immunoreactive to protein kinase C-. EM immunocytochemistry (using a polyclonal antibody) reveals protein kinase C immunoreactivity in photoreceptor cells, bipolar cells, amacrine cells and ganglion cells. In photoreceptors protein kinase C immunoreactivity occurs as patchy staining associated with vesicles and the plasmalemma in pedicles and telodendria. Some varieties of bipolar cell display protein kinase C reaction product throughout the entire cell. Their dendrites contact photoreceptor pedicles at wide-cleft basal junctions and ribbon and non-ribbon related narrow cleft junctions. A few lateral elements per cone or rod pedicle are always protein kinase C-immunoreactive. Amacrine and ganglion cells typically show small clumps of protein kinase C immunoreactivity around vesicles and close to the postsynaptic membranes. Synaptic boutons of some varieties of amacrine cell stain more uniformly. Protein kinase C-immunoreactive bipolar cells are most commonly presynaptic in stratum 4 of the inner plexiform layer, while protein kinase C-immunoreactive amacrine cells are both pre- and postsynaptic throughout strata 1, 2, 3 and 4. Stratum 5 appears to be almost devoid of protein kinase C-immunoreactive neural profiles.