Smoking-associated changes in the serotonergic systems of discrete regions of human brain

This paper describes the results of a postmortem study of the effects of tobacco smoking on the concentrations of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) as well as the binding of [3H]-8-hydroxy-(di-n-propylamino)-tetralin ([3H]-8-OH-DPAT) and [3H]-ketanserin in six discrete regions of human brain. Smoking was associated with significant decreases in the concentrations of 5-HIAA in the hippocampal neocortex (P less than 0.001), hippocampal formation (P less than 0.05) and the median raphe nuclei (P less than 0.05). The 5-HT level of the hippocampal formation was also significantly reduced in smokers (P less than 0.05). These changes were accompanied by significant increases in the binding of [3H]-8-OH-DPAT in the hippocampal neocortex (P less than 0.01) and hippocampal formation (P less than 0.05). [3H]-Ketanserin binding in the brain regions studied was unaffected by smoking. It is concluded that smoking is associated with a regionally selective decrease in the activity of the serotonergic system of the human hippocampus.