Neuroendocrine evidence for reduced serotonergic neurotransmission during heavy drinking.

A fenfluramine (60-mg oral dose) challenge test was performed in 19 male heavy drinkers (mean daily consumption 88 g of pure alcohol). Twelve healthy males served as controls. The prolactin and temperature responses to fenfluramine were significantly reduced in the group of heavy drinkers. The results suggest impaired central serotonergic neurotransmission in alcoholism, possibly involving subsensitivity in various serotonin receptor subtypes.