Neurochemical anatomy of the zebrafish retina as determined by immunocytochemistry.

The zebrafish retina is rapidly becoming a major preparation for the study of molecular genetic mechanisms underlying neural development and visual behavior. Studies utilizing retinal mutants would benefit by the availability of a data base on the distribution of neurotransmitter systems in the wild-type fish. To this end, the neurochemical anatomy of the zebrafish retina was surveyed by light microscopic immunocytochemistry. An extensive series of 60 separate antibodies were used to describe the distribution of major transmitter systems and a variety of neuron-associated membrane channels and proteins. These include markers (i.e., antibodies against enzymes, receptors, transporters) for transmitters: GABA, glycine, glutamate, biogenic amines, acetylcholine, cannabinoids and neuropeptides; as well as a sample of voltage-gated channels and synapse associated membrane proteins. Discussion of the comparative localization of these antibodies is restricted to other teleost fishes, particularly goldfish. Overall, there was great similarity in the distribution of the various markers, as might be expected. However, there were some notable differences, including several antibodies that did not label zebrafish at all, even though goldfish retinas that were processed in parallel, labeled beautifully. This survey is extensive, but not exhaustive, and hopefully will serve as a valuable resource for future studies of the zebrafish retina.