Vasoactive intestinal peptide stimulates proenkephalin A mRNA expression in bovine adrenal chromaffin cells.

The effects of vasoactive intestinal peptide (VIP) and substance P (SP) on the amount of proenkephalin A (ProEnk A) mRNA in cultures of bovine adrenal chromaffin cells were examined. Exposure of chromaffin cells to 5 microM VIP for 24 h produced a significant elevation in ProEnk A mRNA. The stimulatory effect of VIP could be abolished by the presence of the calcium channel blocker D600 or actinomycin D but was not affected by the nicotinic antagonist hexamethonium. The results suggest that VIP may induce transcription of ProEnk A mRNA by a Ca2+-dependent, non-cholinergic mechanism. By contrast, SP (5 microM) had no effect on the amount of ProEnk A mRNA. Since VIP is found in nerve terminals and the ganglion cells within the adrenal medulla, this peptide could be an endogenous regulator of adrenal enkephalin gene expression.