Distribution of .GAMMA.-Aminobutyric Acid (GABA) and the Calcium-binding Protein Parvalbumin in Rat Retina During Development.

Abstract

We investigated immunohistochemically the distribution of γ-aminobutyric acid (GABA) and the calcium-binding protein parvalbumin (PV) in postnatal rat retina. At birth, GABA was found in the ganglion cell layer and in some cells in the nuclear layer that differentiate to amacrine cells and horizontal cells, while PV appeared in some cells in the outer portion of the nuclear layer that differentiates to horizontal cells. At P7, when the inner and outer nuclear layers were divided by outer plexiform layer, both GABA and PV were observed in some cells in the ganglion cell layer, amacrine cells, and horizontal cells. As the postnatal day advanced, GABA and PV were observed in some cells in the ganglion cell layer and amacrine cells. PV has been present in the horizontal cells after its appearance, however, the immunoreactivity of GABA was gradually weaker as the postnatal day advanced. Since GABA existed transiently in the horizontal cells in the early postnatal period, it seems that GABA may have some specific function for differentiation of horizontal cells. However, PV has existed in the horizontal cells since they differentiated in the retina, suggesting that PV may be one of the specific marker of horizontal cells.