Histidine-like immunoreactivity in the rat retina.

PURPOSE

Histidine is an indispensable amino acid with an imidazole ring and it is a precursor of histamine, carnosine, and anserine. Histidine has been proposed to act as a neurotransmitter or neuromodulator in mammalian central nervous system (CNS), including retina. In this study, we report histidine-like immunoreactivity in the rat retina with the use of antibodies raised against histidine coupled to bovine serum albumin (BSA) with glutaraldehyde.

METHODS

In order to confirm the specificity of the antiserum toward histidine, immunodots were carried out. Only the histidine conjugate showed immunoreactivity. The rat retinas fixed with glutaraldehyde were used for immunocytochemistry.

RESULTS

Histidine immunoreactivity was identified in the ganglion cell layer (GCL), inner nuclear layer (INL), inner plexiform layer (IPL), and Müller cells of rat retina.

CONCLUSIONS

Histidine may be a precursor of histamine in the inner retina, and Müller cells may play some role in the metabolism of histidine.