CHRONIC-ALCOHOLICS WITHOUT WERNICKE-KORSAKOFF-SYNDROME OR CIRRHOSIS DO NOT LOSE SEROTONERGIC NEURONS IN THE DORSAL RAPHE NUCLEUS

Despite the considerable evidence that alcoholics have perturbation of serotonergic function, there is little pathological evidence for alco hol directly affecting the nervous system, The present study aims to a ssess neuronal loss that occurs as a consequence of alcohol neurotoxic ity in the serotonergic dorsal raphe nucleus (DRN), To that end, the b rains of eight alcoholics and eight age-matched control cases were car efully screened to eliminate serious liver disease, the sequela of thi amine deficiency, Wernicke-Korsakoff syndrome (WKS), and other patholo gical abnormalities, Brains were formalin-fixed for 2 weeks, cut, and then immunohistochemically stained using a monoclonal PH8 antibody spe cific for the rate-limiting enzyme of serotonin synthesis, tryptophan hydroxylase. The morphology of the serotonin-synthesizing neurons and their average size was similar in all cases, However, there was a redu ction in the staining intensity of the reaction product in the DRN ser otonergic neurons of most alcoholics, Neuronal counts on spaced serial sections revealed that there were an estimated average total of 106,1 00 +/- 19,500 serotonergic neurons in the DRN of alcoholics and 108,30 0 +/- 11,800 in the DRN of controls, indicating that in most alcoholic s there is no reduction in the number of these neurons. Therefore, the effect of chronic alcohol consumption on the serotonergic system, in the absence of WKS or liver disease, seems to be functional rather tha n neuropathological.