REGULATION OF INTRACELLULAR CALCIUM AND PREPROTACHYKININ NEUROTRANSMITTER PRECURSOR GENE-EXPRESSION BY PATTERNED ELECTRICAL-STIMULATION IN RAT SYMPATHETIC NEURONS

Experiments were performed to test several predictions of the hypothes is that activity pattern-dependent changes in intracellular free calci um concentration ([Ca2+](i)) might play a role in the translation of a ltered patterns of neuronal activity into changes in neurotransmitter gene expression. It was shown that (1) the Ca2+ channel blocker cadmiu m prevented depolarization-induced preprotachykinin-I (PPT-I) gene rep ression in rat sympathetic neurons; (2) the magnitudes of transient ri ses in [Ca2+](i) were dependent upon the pattern in which a fixed numb er of depolarizing stimuli were delivered; and (3) stimulation at 10 H z for 24 h did not repress PPT-I mRNA, while the same number of pulses delivered in 0.2 s bursts of 50 Hz caused a highly significant reduct ion to 30 +/- 2.5% of control levels.