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E.–J. Lee, L.B. Mann, N.M. Grzywacz; Immunoreactivity to Neuronal Nicotinic Receptor ß2 Subunit in Developing Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5332.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Neuronal nicotinic receptors (nAChRs) form a heterogeneous family of pentameric oligomers made up of combinations of subunits encoded by at least twelve genes. The nAChR ß2 subunit has a major role in spontaneous retinal waves during development. Hence, the ß2 subunit is likely to be present then in a significant fraction of retinal neuronal nicotinic receptors. This study was conducted to identify expression patterns of nAChR ß2 in the developing mouse retina, using immunocytochemistry. Methods: We used retinas of C57BL/6J black mice at embryonic days (E) 15, 16, 18, postnatal days (P) 1, 3, 5, 10, 15, 21, and adult ages. Retinas were immunostained with polyclonal antisera against nAChR ß2 subunit (1:1000, Chemicon). For double labeling, we used monoclonal antisera against calbindin, a specific marker for horizontal cells (1:6000, Sigma). We also used monoclonal antisera against ß–tubulin, a specific marker for neuronal cells (1:500, Sigma) and antisera against ChAT, a specific marker for cholinergic cells (1:300, Chemicon). Results: The nAChR ß2 immunoreactivity first appeared in neuroblasts in the mantle zone of the primitive retina at E16. From P1 onward, strong immunoreactivity appeared in the inner–plexiform (IPL), ganglion–cell (GCL), and neuroblastic layers (NBL). At P3, nAChR ß2 immunoreactivity appeared in somata located in the distal row of the NBL. In contrast, nAChR ß2 immunoreactive cells located in the middle of the NBL disappeared after P5. From P10 onward, the distribution of labeling within the IPL changed from a non–organized to a weakly laminated appearance. However, the intensity decreased gradually with the maturation of the retina. Double– fluorescence immunocytochemistry using an antiserum against ß–tubulin indicated that nAChR ß2 immunoreactive cells in E16 are neuronal cells. Moreover, co–expression of calbindin D–28kDa revealed that nAChR ß2 labeled cells in the distal row of the NBL are horizontal cells. Although the expression level appeared to be low, nAChR ß2 immunoreactivity was observed in some choline acetyltransferase (ChAT) immunoreactive cells. Conclusions: The nAChR ß2 subunits in developing mouse retina are expressed in migration and differentiation of cholinoceptive neurons.
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