Reciprocal hunger-regulating circuits involving alpha- and beta-adrenergic receptors located, respectively, in the ventromedial and lateral hypothalamus.

The injection of adrenergic and adrenolytic drugs directly into the brain through permanently implanted cannulas has yielded results showing that food consumption in the rat is regulated by a hypothalamic alpha-adrenergic "hunger" system. and a hypothalamic beta-adrenergic "satiety" system. The rats' differential responses to alpha-adrenergic and beta-adrenergic drugs injected into different hypothalamic sites indicate the following: (1) the lateral hypothalamic "feeding" center contains beta receptors, the activation of which produces satiation, presumably by inhibition of the lateral "feeding" cells; (2) the ventromedial hypothalamic "satiety" center contains alpha receptors, the activation of which produces eating, presumably by inhibition of the ventromedial "satiety" cells; and (3) the medio-lateral perifornical area of the hypothalamus contains both alpha and beta receptors, which lead to inhibition of the ventromedial or lateral hypothalamic centers respectively. It is suggested that the ventromedial and lateral hypothalamus are connected by reciprocal circuits, so that activation of the ventromedial center results in stimulation of the lateral beta receptors which inhibit the lateral "feeding" cells, and activation of the lateral center results in stimulation of the ventromedial alpha receptors which inhibit the ventromedial "satiety" cells.