Morphological analysis of tyrosine hydroxylase immunoreactive amacrine cell in the guinea pig retina

Abstract

Abstract: : Purpose: This study was conducted to characterize TH immunoreactive cells of the guinea pig retina in more detail. Methods:With immunocytochemistry using specific antisera against TH, whole mount preparations and 50–um –thick vibratome sections were examined by light microscopy. For double–label studies, sections were incubated overnight in a mixture of monoclonal anti–TH antibody (1:1000; Chemicon) with polyclonal anti–GABA (1:2000; Sigma). Results:In the present study, two types of amacrine cells were labeled with antisera against TH. These two types of amacrine cell differ in soma size, plane of arborization in the innerplexiform layer, and population density. The type 1 cells have comparatively large cell bodies almost exclusively in the innermost row of the inner nuclear layer (INL); their processes arbors in the outermost stratum of the inner plexiform layer (IPL); they give rise to fine predominantly radially oriented fibers in the INL. The type 2 amacrine cells have relatively small cell bodies located in the INL, and their processes arborize in the center of the IPL. The mean densities were 40cells/mm² in central and 25 cells/mm² in peripheral for the type 1 cell and 140 cells/mm² in central and 79cells/mm² in peripheral for the type 2 cell. Double immunocytochemistry using an antiserum against GABA revealed that while none of the type 1 cells showed GABA immunoreactivity, all of the type 2cells displayed GABA immunoreactivity. Conclusions:Our results suggest that, in the guinea pig retina, the type 1 amacrine cells are pure dopaminergic and the type 2 cells are dopaminergic cells that use GABA as their second transmitter.

Keywords: retina • retina: proximal (bipolar, amacrine, and ganglion cells) • retinal connections, networks, circuitry