THE EFFECT OF CAFFEINE AN FOOD-INTAKE IN RATS - INVOLVEMENT OF CORTICOTROPIN-RELEASING FACTOR AND THE SYMPATHOADRENAL SYSTEM

The involvement of CRH and the sympatho-adrenal system in the effects of caffeine on food intake and body weight gain has been investigated in rats. Food intake and body weight gain were measured in male rats a fter the treatment with caffeine in combination with either an injecti on of the CRH antagonist alpha-helical CRH((9-41)), a surgical adrenal demedullation (medullectomy), or a ganglionic blockade. Alpha-helical CRH((9-41)), was injected in the lateral ventricle of the brain and h examethonium was used to chemically block the ganglionic transmission. From 4 to 24 h following a caffeine injection, spontaneous food intak e, which was cumulated from the time caffeine was injected, was signif icantly (p < 0.01) lower in caffeine- than in saline-treated rats. In food-deprived rats, the anorectic effect of caffeine was biphasic, bei ng significant at 0.5 and 1 h after the caffeine administration, then vanishing for 3 h, and becoming significant again 6 h after the caffei ne administration. In both the spontaneously fed and food-deprived rat s, caffeine reduced the rate of weight gain, which was measured at the end of a 12- or a 24-h period following the caffeine injection. A sig nificant (p < 0.05) interaction effect of caffeine and alpha-helical-C RH((9-41)) was found on the cumulative food intake at 1, 6, and 8 h, a nd on the amount of food eaten between the 4-6-h interval following th e injection of caffeine; the effects of caffeine on food intake and bo dy weight gain seem largely prevented by the use of a CRH antagonist. Neither the medullectomy nor the ganglionic blockade attenuated the ef fect of caffeine on food intake. There was, in fact, no interaction ef fect of either caffeine and medullectomy or caffeine and hexamethonium on postcaffeine food intake and body weight gain. The present results do not support a role for the sympatho-adrenal system in the effects of caffeine on food intake and body weight. This study, together with providing evidence for a central CRH-mediated anorectic action of caff eine, further emphasizes the role of CRH in the control of food intake .