Effects of nicotine on levels of acetylcholine and biogenic amines in rat cortex

Abstract

Abstract Transcortical dialysis was employed to investigate the effects of systemic nicotine (3.6 μmol/kg, sc) administration on cortical extracellular levels of acetylcholine (ACh), norepinephrine (NE), dopamine (DA), and serotonin (5‐HT). Systemic administration of [–]‐nicotine produced a 106% increase of cortical ACh release over basal levels that persisted for approximately 2 h. Concurrently, NE levels were increased 86% over basal values for 60 min. The effects appear to be stereoselective, as systemic injections of [+]‐nicotine significantly increased cortical ACh levels only 48% over basal levels for 30 min, and NE levels in the dialysate only 43% over control levels for 60 min. No significant changes of basal dopamine (DA) or serotonin (5‐HT) levels were observed, although DA did appear to increase in response to systemic nicotine. In addition, striatal total endogenous ACh increased significantly over control levels 15 min after [–]‐nicotine administration (3.6 μmol/kg, sc), and then significantly declined after 3 h, suggesting that nicotine may influence synthesis as well as release. Analysis of total ACh levels in cortical tissue revealed a similar trend. At the dose utilized in this study, no changes in the cortical electroencephalogram (EEG) were observed. © 1994 Wiley‐Liss, Inc.