CHOLINERGIC STIMULATION OF SKELETAL-MUSCLE CELLS INDUCES RAPID IMMEDIATE-EARLY GENE-EXPRESSION - ROLE OF INTRACELLULAR CALCIUM

Many properties of skeletal muscle are closely regulated by motor nerves. We have shown that nerve stimulation in vivo induced a rapid rise in mRNA for the immediate early gene (IEG) zif268 in stimulated muscle. However, the mechanisms leading to neural regulation of zif268 gene expression in muscle are not yet known. in this study, we used a mammalian skeletal muscle cell line (C2C12) to analyze the role of cholinergic transmission, and calcium flux, in the neural regulation of zif268. Treatment of the C2C12 muscle cells with carbachol, a cholinergic agonist, induced zif268 gene expression rapidly and transiently. This effect was blocked by alpha-bungarotoxin (alpha-BuTx), which specifically blocks nicotinic acetylcholine receptors. Treatment with ryanodine or dantrolene, which block the calcium release channel of the sarcoplasmic reticulum, inhibited the carbachol-induced zif268 response essentially completely. Calcium influx produced by A23187, a calcium ionophore, induced an increase of zif268 gene expression equivalent to the effect of carbachol stimulation. These results suggest that the effect of neural stimulation on zif268 may be attributable to cholinergic transmission, and the subsequent release of calcium from the sarcoplasmic reticulum.