Fenfluramine-like potentiation of morphine anorexia in lateral hypothalamic rats

Recent experiments have implicated endogenous opioids in feeding in normal and obese animals. We now report on the influence of morphine in rats which have recovered from the initial aphagia resulting from lesions of the lateral hypothalamus (HL). We have examined morphine's influence on feeding in the LH rat in order to determine whether its action is similar to amphetamine or fenfluramine or different from both drugs. As yet there is insufficient evidence on the specificity of morphine's anorexia or its mode of action to rule out other interpretations although the marked difference from amphetamine anorexia suggests that, in accordance with a recent study on morphine induced motility in rats, morphine anorexia is not primarily mediated by catecholamines.