Vardi N, Sterling P
Department of Neuroscience, University of Pennsylvania, Philadelphia 19104-6058.
Vision Res. 1994 May;34(10):1235-46. doi: 10.1016/0042-6989(94)90198-8.
The subcellular distribution of GABAA receptor in the macaque and human retina was studied by immunocytochemistry with monoclonal antibodies for the alpha and beta subunits with a particular focus on bipolar cells. Immunoreactivity to GABAA receptor was present on dendritic tips of all bipolar cells. The stain was strongest on bipolar membranes in apposition to horizontal cell processes. Stain was concentrated on the tips of flat and invaginating cone bipolar cells at the base of the cone pedicle and on the invaginating tips of rod bipolar cells. Stain on the cone pedicle membrane was restricted to sites of apposition to stained bipolar dendrites; pedicle membrane in apposition to horizontal cell processes was unstained. Stain was also present on bipolar axon terminals in both on and off strata of the inner plexiform layer. All bipolar cell somas stained faintly; horizontal and Müller cell somas were unstained. The alpha and beta subunits distributed similarly in monkey and human retina. Presence of GABAA receptor on the bipolar dendritic tips suggests that horizontal cells directly affect bipolar cells. Thus, GABAA receptor might mediate the receptive field surround of both off and on bipolar cells. Presence of GABAA receptor on bipolar axon terminals suggests that much of the inhibition feeding back from GABAergic amacrine to bipolar cells is GABAA-mediated.
采用针对α和β亚基的单克隆抗体，通过免疫细胞化学方法研究了猕猴和人类视网膜中GABAA受体的亚细胞分布，特别关注双极细胞。所有双极细胞的树突尖端均存在对GABAA受体的免疫反应性。在与水平细胞突起相邻的双极细胞膜上，染色最强。染色集中在视锥小足基部的扁平型和内陷型视锥双极细胞的尖端以及杆状双极细胞的内陷尖端。视锥小足膜上的染色仅限于与染色的双极树突相邻的部位；与水平细胞突起相邻的小足膜未染色。在内网状层的ON层和OFF层中，双极轴突终末也有染色。所有双极细胞的胞体染色较淡；水平细胞和米勒细胞的胞体未染色。α和β亚基在猴和人类视网膜中的分布相似。双极树突尖端存在GABAA受体表明水平细胞直接影响双极细胞。因此，GABAA受体可能介导OFF双极细胞和ON双极细胞的感受野周边。双极轴突终末存在GABAA受体表明，从GABA能无长突细胞反馈到双极细胞的大部分抑制作用是由GABAA介导的。
