Localization of Guanine Aminohydrolase in the Postnatl Developing Rat Retina

Lee, Hwa Young

Abstract

Guanine aminohydrolase (GAH; Guanine deaminase, EC 3.5.4.3) is an enzyme that has a role in purine catabolism. Most of the enzymes involved in purine catabolism have been studied for their biological functions, physiological roles and amino acid sequences, and biochemical activity of GAH is known to be detected in various organs such as liver, kidney, small intestine and brain. Its activity is also known to be changed during development of the nervous system. Although there have been studies on GAH, the histological distribution of GAH in the rat retina has not been examined until now. In this study, in order to investigate the cellular distribution and temporal regulation of GAH in rat retina, we performed immunohistochemistry in retinal sections at different developmental ages between postnatal day 0 (P0, birthdate) and the adult stage using specific antibody against GAH. GAH immunoreactivity was observed in the ganglion cell layer and inner plexiform layer at P0. From P5, GAH staining appeared in the inner part of the neuroblast layer, where amacrine cells localize. At P14, labeling of GAH also was observed in horizontal cell bodies and in the outer plexiform layer. Immunoreactivity of GAH in horizontal cell bodies was increased and strong punctate reactivity was observed in the outer plexiform layer at the adult rat retina, whereas the number and intensity of immunoreactive amacrine cell bodies in the inner part of inner nuclear layer decreased. From these results, we can suggest that GAH may be involved in the establishment of synaptic connections and signal transduction in the developing rat retina.