SPECIFIC REGULATION OF IMMEDIATE-EARLY GENES BY PATTERNED NEURONAL-ACTIVITY

Electrical activity shapes development of the nervous system, presumab ly in part by regulating gene expression. A set of regulatory genes, i mmediate early genes (IEGs), which are responsive to a number of extri nsic cellular stimuli have been proposed to play a role in coupling su ch activity to gene expression. Using a semiquantitative polymerase ch ain reaction assay, we show that in dissociated mouse dorsal root gang lion neurons the expression of two IEGs, c-fos and nur/77, is differen tially sensitive to patterns of electrical stimulation. Differences in c-fos activation did not correlate with the peak intracellular calciu m [Ca++]i produced by the different stimulation patterns or with resid ual [Ca++]i following stimulation. However, the net increase in [Ca++] i (calcium time integral) was greater for the pulsed stimulus that act ivated c-fos (6 impulses/min), compared to the ineffective stimulus (1 2 impulses/2 min). This system of genes seems suited to mediating the coupling between electrical activity and other functional genes. (C) 1 993 Wiley-Liss, Inc.