Effects of thyrotropin-releasing hormone and metoclopramide on PRL secretion in normally cycling and amenorrheic alcoholic women

Abstract

To assess the possible influence of alcoholism on the dopaminergic inhibitory control of prolactin (PRL) secretion, 10 mg of the dopaminergic antagonist metoclopramide (MTC), was injected i.v. in a group of eight healthy abstemious women (aged 28 ± 6 (mean ± S.E.) years) and in 16 age-matched nondepressed female alcoholic subjects after 3–4 weeks of abstinence from alcohol. All normal controls and eight alcoholics had normal menstrual cycles and were tested in the early follicular phase (4–8 days), the remaining eight alcoholics were affected by amenorrhea (duration: 15 ± 3 months). During the same period, all patients were also tested with TRH (200 μg in an i.v. bolus) to determine whether the pituitary PRL cell secretory capacity was preserved in alcoholics. The amenorrheic alcoholic group showed strikingly lower circulating estrogen levels than normally cycling groups. Similar basal PRL levels and PRL responses to TRH were observed in normal controls and normally cycling alcoholics, whereas basal and TRH-stimulated PRL levels were significantly higher in amenorrheic alcoholics. In contrast, the PRL response to MTC was significantly higher in cycling alcoholic patients than in normal controls and amenorrheic alcoholic subjects. However, when the statistical analysis of MTC test took into account the difference in estrogen levels among groups, the statistical differences in the PRL responses to MTC observed between normally cycling and amenorrheic alcoholics disappeared. These data suggest the presence of an enhanced dopaminergic inhibitory control of PRL secretion in 2–3 week abstinent alcoholics with normal menstual cycles and normal circulating estrogen levels. In contrast, amenorrhea in abstinent alcoholics appears to be associated with an enhancement of PRL cell secretory activity.