SELECTIVE UP-REGULATION OF NEUROPEPTIDE SYNTHESIS BY BLOCKING THE NEURONAL-ACTIVITY - GALANIN EXPRESSION IN SEPTOHIPPOCAMPAL NEURONS

Neuronal activity regulates expression of phenotype-specific genes, in cluding galanin, which coexists with choline acetyltransferase in sept al and basal forebrain neurons. Transections of the fornix and the dia gonal band alter galanin expression in septohippocampal neurons attrib uted to a deficit in target-derived trophic factors. The present study demonstrates that tetrodotoxin-induced blockade of neuronal activity fully mimicked the effect of axotomy (transection of the septohippocam pal fibers) in the neurons of the nucleus of the diagonal band, and ca used a dramatic, although temporary, up-regulation of galanin immunore activity and galanin mRNA without significant alteration in choline ac etyltransferase expression. This finding suggests that in the septohip pocampal cholinergic system perturbance of electrical activity alone c an lead to temporary up-regulation of galanin expression, previously a ttributed exclusively to a ''lesion effect.'' (C) 1994 Academic Press, Inc.