Nicotine elicits changes in expression of adrenal catecholamine biosynthetic enzymes, neuropeptide Y and immediate early genes by injection but not continuous administration

Abstract

Nicotine, a major pharmacologically active component of tobacco smoke, is generally believed to be one of the factors responsible for the deleterious consequences of cigarette smoking. Nicotine activates the sympathoadrenal system and increases the synthesis and release of catecholamines into circulation. In this study we show that single and repeated injections of nicotine increase the expression of tyrosine hydroxylase (TH), a rate limiting enzyme in the catecholamine biosynthetic pathway. These treatments also regulated the expression of dopamine beta-hydroxylase (DBH) and neuropeptide Y (NPY) in rat adrenals. The effect of nicotine on several transcription factors in the adrenal medulla was examined. Nicotine administration by injection increased the phosphorylation of CREB and induced c-Fos protein without affecting members of the jun family. In contrast to the results with injections, continuous infusion via osmotic pumps did not affect any of these parameters. These data indicate that activation of several transcription factors and increased expression of TH, DBH, and NPY is dependent on the mode of nicotine administration.