These experiments test the effect of intraperitoneal injection of lysine acetylsalicylate on 1) food intake and 2) the sympathetic and thermogenic changes induced by lesion of the lateral hypothalamus (LH). Food intake, firing rate of the nerves innervating interscapular brown adipose tissue (IBAT), and IBAT and colonic temperatures (TIBAT and TC) were monitored in male Sprague-Dawley rats lesioned in the LH. These variables were measured before and after intraperitoneal injection of lysine acetylsalicylate. The same variables were also monitored in 1) lesioned rats with intraperitoneal administration of saline, 2) sham-lesioned animals with intraperitoneal injection of lysine acetylsalicylate, and 3) sham-lesioned rats with intraperitoneal injection of saline. The results show that lysine acetylsalicylate modifies the aphagia by increasing food intake and also reduces the enhancements in firing rate, TIBAT, and TC induced by LH lesion. These findings suggest that prostaglandin synthesis plays a key role in the control of eating behavior in LH-lesioned rats by acting on the sympathetic and thermogenic changes induced by LH lesion.