E-mail: marsol214@hotmail.com

Several evidences demonstrate an interaction between lead (Pb) and ethanol. Specifically we have reported a higher reactivity to the stimulant effects of ethanol in developmentally low-level Pb exposed rats. This study aimed to compare the influence of perinatal low-level Pb exposure on the motivational properties of ethanol by using a two-bottle ethanol/water test and an operant oral ethanol self-administration task. In addition, on the basis of the hypothesis that centrally-formed acetaldehyde has reinforcing effects (as opposed to peripheral acetaldehyde) we sought to explore the influence of ethanol metabolism in this experimental model. Thirty-five day-old male Wistar pups perinatally exposed to 220 ppm Pb were evaluated in their ethanol intake in a free-choice limited paradigm (2 h) at increasing ethanol concentrations (2-10%). Another group of animals was trained to associate the contingency of a lever press with 10% ethanol administration under a fixed-ratio 1 (FR 1) schedule of behavior, which was increased progressively across sessions to FR2, 5, 10, and 20. Aminotriazole, an inhibitor of acetaldehyde formation, and cyanamide, a drug that block acetaldehyde metabolism were centrally and systemically administered. The results demonstrated that Pb-exposed rats voluntarily consumed more ethanol than their respective controls. In the same way, Pb-exposed animals worked harder than the controls to obtain ethanol in an operant schedule of behavior, evidencing a ?break point? at higher lever-press rates. Moreover, the relationship between central and peripheral acetaldehyde modified these behaviors, revealing the importance of this metabolite in the motivational effects of ethanol in developmentally Pb-exposed rats.