Colocalization of vasoactive intestinal polypeptide and GABA immunoreactivities in a population of wide-field amacrine cells in the rabbit retina.
Vasoactive intestinal polypeptide (VIP) immunoreactive (IR) neurons in the rabbit retina constitute a population of wide-field amacrine cells. To better define this cell population, we examined the coexpression of VIP with other putative retinal transmitters or their biosynthetic enzymes, including gamma-aminobutryic acid (GABA), tyrosine hydroxylase (TH), and somatostatin (SRIF). Colchicine-treated retinas were immersion fixed in 4% paraformaldehyde. The retinas were cut either perpendicular or parallel to the vitreal surface and processed by double-label immunofluorescence techniques using antibodies directed to VIP, GABA, TH, and SRIF. The immunoreactive staining patterns obtained with these antibodies were the same as those described in previous studies. GABA-IR neurons were localized to the proximal inner nuclear layer (INL) and ganglion cell layer (GCL) and processes were distributed throughout the inner plexiform layer (IPL). TH- and SRIF-IR neurons were sparsely distributed to the proximal INL and GCL, respectively. TH-IR processes ramified in laminae 1, 3, and 5, and SRIF-IR processes in laminae 1 and 5 of the IPL. Colocalization experiments showed that all VIP-IR neurons contain GABA immunoreactivity. In contrast, colocalization of VIP and TH or SRIF immunoreactivities was never observed. These results demonstrate that VIP-IR wide-field amacrines of the rabbit retina make up a neurochemically and morphologically distinct subpopulation of the GABA-IR amacrine cell population. Furthermore, VIP-IR amacrine cells constitute a distinct group with respect to the TH- and SRIF-IR amacrine cells.
Casini
G
G
Department of Anatomy and Cell Biology, UCLA School of Medicine.
Brecha
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NC
D000818:Animals; D005455:Fluorescent Antibody Technique; D010641:Phenotype; D011817:Rabbits; D012160:Retina / Q000737:chemistry* / Q000166:cytology; D013004:Somatostatin / Q000032:analysis; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis; D014660:Vasoactive Intestinal Peptide / Q000032:analysis*; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D014660:Vasoactive Intestinal Peptide; D013004:Somatostatin; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase