Effects of nerve growth factor and nicotine on the expression of nicotinic acetylcholine receptor subunits in PC12 cells.

The neuroprotective effect of nicotine via nicotinic acetylcholine receptor (nAChR) has been reported in differentiated PC12 cells. We examined the effects of nerve growth factor (NGF) and nicotine on the expressions of the nAChR subunits alpha3, alpha5, alpha7, beta2, beta3 and beta4, in PC12 cells using Northern blot analysis. NGF increased the transcriptions of alpha5 (1,4- to 2,3-fold), alpha7 (1.7- to 2.5-fold) and beta4 (1.9- to 3.0-fold) subunits, but changes in alpha3 and beta2 subunit levels were smaller than alpha5, alpha7, or beta4. Nicotine also increased the levels of mRNA encoding alpha5 and beta2 subunits. The pattern of subunit mRNA changes was different between NGF and nicotine treatment. No signal for beta3 subunit was detected. The results suggest that NGF changes the expression of nAChR in a subtype-specific manner over the course of the differentiation, and the disproportionate subunit expressions might be related to the neuroprotective effect exerted by nicotine.