Dopamine cells and rod bipolar cells contain protein kinase C-like immunoreactivity in some vertebrate retinas.

The localization of cells immunoreactive to a monoclonal antibody against protein kinase C (PKC) and to polyclonal antibodies against tyrosine hydroxylase (TH) was investigated in the retina of fish (carp, goldfish, dace and catfish), frog, turtle, chick and some mammalians (guinea pig, rat, cat and rabbit) by means of fluorescence microscopy. PKC-like immunoreactivity was found in dopamine (DA) or TH-like immunoreactive (IR) cells in all the species examined and also in rod bipolar cells in the fish (except for catfish), and in presumed rod bipolar cells in the other animals (except for frog and turtle). In the catfish, frog and turtle retinas, no PKC-like IR bipolar cells were found. In the rat retina, some other amacrine cells in addition to TH-like IR amacrine cells were reactive to the anti-PKC antibody. It is of interest that PKC-like immunoreactivity is commonly found in DA cells and probably in rod bipolar cells in most animal species, although the functional significance is unknown at present.