CUES INTRINSIC TO THE RETINA INDUCE NACHR GENE-EXPRESSION DURING DEVELOPMENT

Recent studies of optic nerve regeneration in goldfish have indicated that the optic tectum plays an important role in modulating the induct ion of nicotinic acetylcholine receptor (nAChR) gene expression in reg enerating retinal ganglion cells (Hieber, Agranoff, and Goldman, 1992, J. Neurochem. 58:1009-1015). These observations suggest that inductio n of these genes is regulated by brain target regions. The appearance of nAChR mRNA in the developing rat retina coincides with a time when ganglion cells are sending axons to their brain targets (Hoover and Go ldman, 1992, Exp. Eye Res. 54:561-571). Might a mechanism similar to t hat seen during goldfish optic nerve regeneration also mediate inducti on of nAChR gene expression during development of the mammalian retina ? This possibility was tested by either transplanting embryonic rat re tina to different brain regions, or explanting it to organ culture and assaying for nAChR gene expression. These studies showed that inducti on of the nAChR genes in developing rat retina is independent of the e nvironment in which the retina develops. These results indicate that e ither the retinal microenvironment or a signal intrinsic to the retina l ganglion cell is responsible for this induction. (C) 1993 John Wiley Sons, Inc.