Synaptic regulation of immediate early gene expression in primary cultures of cortical neurons

• Published in: Journal of neurochemistry Vol. 57; no. 6; p. 1862
• Main Authors: Murphy, T H, Worley, P F, Nakabeppu, Y, Christy, B, Gastel, J, Baraban, J M
• Format: Journal Article
• Language: English
• Published: England 01-12-1991
• Subjects: Animals; Cells, Cultured; Cerebral Cortex - cytology; Cerebral Cortex - physiology; Electrophysiology; Gene Expression Regulation - drug effects; Genes, fos; Genes, jun; Immunologic Techniques; Neurons - physiology; Picrotoxin - pharmacology; Staining and Labeling; Synapses - physiology
• ISSN: 0022-3042
• DOI: 10.1111/j.1471-4159.1991.tb06396.x

Neuronal stimulation can rapidly activate several immediate early genes that code for transcription factors. We have used primary cortical cultures to study the regulation of four of these genes, c-fos, c-jun, jun-B, and zif268. Immunocytochemical studies with antibodies to Jun-B, c-Jun, and c-Fos demonstrate intense staining in the nuclei of a subset of cortical neurons in mature cultures (21-25 days in vitro) but not young cultures (3-7 days in vitro). To assess whether this immunoreactivity may be induced by spontaneous synaptic activity that develops with a similar profile, we examined the effects of agents that reduce this synaptic activity. Tetrodotoxin or N-methyl-D-aspartate receptor antagonists suppress basal immunoreactivity to Jun-B and c-Fos, but not c-Jun, indicating that the basal level of c-Jun expression is not dependent on electrical activity. Picrotoxin, an agent that increases synaptic excitation indirectly by blocking inhibitory synaptic currents mediated by gamma-aminobutyric acidA receptors, markedly increases the percentage of neurons displaying immunoreactivity to c-Fos, c-Jun, Jun-B, and Zif268. Northern analysis suggests that the increases in immunostaining induced by picrotoxin are secondary to a rapid increase in mRNA for these proteins. These findings provide evidence for rapid transcriptional regulation of immediate early genes in cortical neurons by synaptic activity.