IMMUNOCYTOCHEMICAL LOCALIZATION OF THE GABA(C) RECEPTOR RHO-SUBUNIT IN THE CAT, GOLDFISH, AND CHICKEN RETINA

Polyclonal antibodies against the N-terminus of the rat pi subunit wer e used to study the distribution of gamma-aminobutyric acid C (GABA(C) ) receptors in the cat, goldfish, and chicken retina. Strong punctate immunoreactivity was present in the inner plexiform layer (IPL) of all three species. The punctate labelling suggests a clustering of the GA BA(C) receptors at synaptic sites. Weak label was also found in the ou ter plexiform layer (OPL) and over the cell bodies of bipolar cells. D ouble immunostaining of vertical sections with an antibody against pro tein kinase C (PKC) showed the punctate immunofluorescence to colocali ze with bipolar cell axon terminals. In the goldfish retina, the axon terminals of Mb1 bipolar cells were enclosed by rho-immunoreactive pun cta. In the chicken retina, several distinct strata within the IPL sho wed a high density of rho-immunoreactive puncta. The results suggest a high degree of sequence homology between the rho subunits of differen t vertebrate species, and they show that the retinal localization of G ABA(C) receptors is similar across different species. (C) 1997 Wiley-L iss, Inc.