The effect of chronic administration of nicotine and withdrawal on somatostatin concentration and binding in brain of rat.

The effects of chronic administration of nicotine (20 or 30 days) and its withdrawal on somatostatin-like immunorectivity and the binding of 125I-Tyr11-somatostatin in the frontoparietal cortex and hippocampus of the rat were investigated. Chronic administration of nicotine resulted in a decrease in the total number of specific somatostatin receptors, while the affinity of the receptors was unaltered and somatostatin-like immunoreactivity was unchanged in both areas of the brain. Three weeks after ending chronic exposure to nicotine in the second experimental group, the number of somatostatin receptors had returned to the same values as those of saline-treated rats.