Amygdala serotonin transporters in alcoholics measured by whole hemisphere autoradiography

Background: A dysfunction in brain serotonin turnover is a well-established factor associated with the impulsive and sociopathic behavior in alcoholics. The conjuncted alterations in functioning of serotonin transporter (SERT) may play a role in the regulation of emotional balance, judgement, and the adverse behavioral effects of ethanol misuse. These traits may be related to serotonergic regulation in the amygdala and prefrontal cortex. Methods: The binding of [H-3]citalopram to SERT was evaluated in the amygdala of Cloninger type 1 and 2 alcoholics (n = 17), and nonalcoholic control subjects (n = 10) by postmortem whole-hemisphere autoradiography. Results: The SERT binding was substantially lower in the dorsal amygdala in alcoholic subjects when compared with the controls (-28%, effect size 1.26, P = 0.016). In secondary analysis, this reduction was observed in both alcoholic subgroups (-26% in type 1 alcoholics, and -33% in type 2 alcoholics). In ventral amygdala, no alteration was observed. There were significant correlations between the SERT binding in dorsal amygdala and in previous results from frontal cortical areas in alcoholics, depending on the type of alcoholic. Conclusions: These results suggest that SERT binding in the amygdala, as well as the differential regulation of the SERT in amygdala and frontal cortex in alcoholics may help to explain the dysfunctional regulation of emotions in alcoholics.