Amacrine, ganglion, and displaced amacrine cells in the rabbit retina express nicotinic acetylcholine receptors

Acetylcholine (ACh) in the vertebrate retina affects the response propertie s of many ganglion cells, including those that display directional selectiv ity. Three beta and eight alpha subunits of neuronal nicotinic acetylcholin e receptors (nAChRs) have been purified and antibodies have been raised aga inst many of them. Here we describe biochemical and immunocytochemical stud ies of nAChRs in the rabbit retina. Radioimmunoassay and Western blot analy sis demonstrated that many of the nAChRs recognized by a monoclonal antibod y (mAb210) contain beta2 subunits, some of which are in combination with al pha3 and possibly other subunits. MAb210-immunoreactive cells in the inner nuclear layer (INL) were 7-14 mum in diameter and were restricted to the in nermost one or two tiers of cells, although occasional cells were found in the middle of the INL. At least 60% of the cells in the ganglion cell layer (GCL) in the visual streak displayed mAb210 immunoreactivity; these neuron s ranged from 7-18 mum in diameter. The dendrites of cells in both the INL and GCL could sometimes be followed until they entered one of two dense, po orly defined, bands of processes in the inner plexiform layer (IPL) that ov erlap the arbors of the cholinergic starburst cells. Parvalbumin and seroto nin-positive neurons did not exhibit nAChR immunoreactivity. Although the l evel of receptor expression appeared to be low mAb210 immunoreactivity was observed in some of the ChAT-positive (starburst) amacrine cells.