Behavioral and neuroendocrine responses to m-chlorophenylpiperazine in subtypes of alcoholics and in healthy comparison subjects.

OBJECTIVE

The purpose of this study was to explore central serotonergic functions in subgroups of alcoholics and in healthy comparison subjects.

METHOD

The mixed serotonin (5-HT) agonist/antagonist m-chlorophenylpiperazine (m-CPP) was administered to male alcoholic patients who were classified according to the criteria of von Knorring et al. as type I alcoholics (late onset) (N = 16) or type II alcoholics (early onset with antisocial traits) (N = 24) and to 22 healthy comparison subjects. Psychological, physiological, and neuroendocrine measures were obtained before and after the m-CPP infusion.

RESULTS

m-CPP elicited subtype-related differential effects among the alcoholics; the type I alcoholics reported more anger and anxiety, and the type II alcoholics reported increased euphoria and a greater likelihood of drinking. The healthy comparison subjects exhibited a greater increase in plasma ACTH response to the m-CPP infusion than the alcoholics regardless of subtype.

CONCLUSIONS

Differences in certain 5-HT receptor functions may explain some of the clinical characteristics that differentiate the type II and type I subgroups of alcoholic patients. Furthermore, alcoholics may have reduced sensitivity of 5-HT2C receptors in comparison with healthy subjects.