Effects of nicotine withdrawal on central dopaminergic systems

The behavioral and neurochemical manifestations in rats 24 h following the cessation of 14-day nicotine administration were investigated. Animals were implanted subcutaneously with osmotic minipumps which continuously released either saline or nicotine (1.5 mg/kg/day or 3.0 mg/kg/day) for 14 days. After the animals were withdrawn from nicotine for 24 h, we observed a significant decrease of locomotor activities and a reduction of dopamine contents in the striatum and nucleus accumbens. Nicotine withdrawal did not affect the body weight, food, or water consumption, and no deficit in the acquisition of a conditioned avoidance task was found in these animals. In addition, nicotine withdrawal did not alter the density or the binding affinity (Kd) of ligands to D1 and D2 receptors in the striatum. Although nicotine withdrawal did not alter the density or binding affinity of ligands to D1 receptors in the nucleus accumbens, the maximum number of D2 receptor sites were reduced by nicotine treatment. These results offer possible neurochemical mechanisms for changes of locomotor activity which occurred in rats during nicotine abstinence.