Stimulation of food intake in rats by the alpha 2-adrenoceptor agonists xylazine and detomidine.

Effects of the alpha 2-adrenoceptor agonists xylazine and detomidine on food intake in freely feeding male rats were evaluated. Intraperitoneal (i.p.) injection of xylazine (0.25-3 mg/kg) and detomidine (25 and 50 micrograms/kg) significantly increased the 2 and 24 h food intake from control values. Treatment of rats with the alpha 2-adrenoceptor antagonist yohimbine (1 mg/kg, i.p.) 15 min before xylazine (0.5 mg/kg, i.p.) or detomidine (50 micrograms/kg, i.p.) significantly inhibited the increase in food intake. Yohimbine treatments alone at 0.5, 1 and 2 mg/kg, i.p. did not significantly change the 2 and 24 h food intake from control values. The results suggest that the alpha 2-agonists xylazine and detomidine enhance food intake in rats.