TRANSIENT, HIGH-LEVELS OF SNAP-25 EXPRESSION IN CHOLINERGIC AMACRINE CELLS DURING POSTNATAL OF THE DEVELOPMENT OF THE MAMMALIAN RETINA

In the present study, we have examined the development of cholinergic amacrine cells in the retina of the Brazilian opossum, Monodelphis dom estica. An antibody directed against choline acetyltransferase (ChAT) revealed that ChAT-like immunoreactivity (ChAT-IR) was first observed at 15 days postnatal (15PN). By 25PN, ChAT-IR identified two matching populations of amacrine cells in the inner nuclear and ganglion cell l ayer. Bromodeoxyuridine birth-dating analysis coupled with immunolabel ing with the anti-ChAT antibody revealed that the cholinergic amacrine cells are born postnatally, between 2PN and 15PN. In addition, we hav e examined the differentiation of the cholinergic amacrine cells by us ing an antibody directed against a presynaptic terminal-associated pro tein, synaptosomal-associated protein of 25 kDa (SNAP-25). Double-labe ling analysis revealed that relatively high levels of SNAP-25-IR were selectively present in cholinergic amacrine cells prior to eye opening . However, in the mature retina, high levels of SNAP-BB-IR were no lon ger observed in the ChAT-IR amacrine cells. These results reveal a dis tinct period in development, prior to eye opening, when high levels of SNAP-BB-IR are selectively expressed in cholinergic amacrine cells, T he specificity and time course of the high levels of SNAP-25 in cholin ergic amacrine cells may be critical in mediating the transient proper ties of these calls during visual system development. (C) 1998 Wiley-L iss, Inc.