Cholinergic and dopaminergic amacrine cells differentially express calcium channel subunits in the rat retina

Abstract

Immunofluoresence labeling was performed to study the expression of high voltage-activated Ca 2+ channel subunits on rat retinal cholinergic and dopaminergic amacrine cells, which were double labeled with antibodies against choline acetyltransferase and tyrosine hydroxylase, respectively. The α 1A subunit was predominantly expressed on the processes but not on the somata of cholinergic amacrine cells, whereas staining for α 1B and α 1E was observed in both structures of the cells. Immunoreactivity of α 1C and α 1D was not found in the cholinergic amacrine cells. Dopaminergic amacrine cells, on the other hand, exhibited a differential expression pattern of the Ca 2+ channel subunits, with α 1A, α 1C and α 1E being expressed on both somata and processes and α 1B predominantly on the processes of the cells. No α 1D labeling was seen. These results suggest that Ca 2+ channel subunits differentially expressed on the cholinergic and dopaminergic amacrine cells may endow these two cell types with different physiological properties.