The effect of chronic nicotine and withdrawal on intra-axonal transport of acetylcholine and related enzymes in sciatic nerve of the rat.

The content of acetylcholine (ACh) and activities of the cholinergic enzymes choline (acetyltransferase (CAT) and ACh-esterase (AChE) were studied in intact and crushed rat sciatic nerve after chronic nicotine administration and withdrawal 2 days before the final experiment. Nicotine was given in the drinking water during 8-10 weeks and the final dose reached was about 8 mg/kg/day i.e. equivalent to that of the heavy cigarette smoker. In the chronic nicotine group, ACh levels and AChE activity of uncrushed nerve were significantly decreased as compared to the controls. The accumulation of ACh and AChE proximal to a single crush was also somewhat decreased, but significant only for AChE at 18 hours postoperatively. After withdrawal of nicotine for 2 days the ACh content of both uncrushed and 12 hours crushed nerves were further decreased, while AChE was instead increased to control (uncrushed) or even supranormal (18-hour crush) levels.