Hypothalamic alpha 2- and beta-adrenoceptor rhythms are correlated with circadian feeding: evidence from chronic...

The circadian regulation of food intake in rats is correlated with a bimodal rhythm of beta-adrenoceptor binding in the lateral hypothalamus and a unimodal rhythm of alpha 2-adrenoceptor binding in the medial hypothalamus. Chronic methamphetamine treatment provides evidence for a functional correlation: beta-adrenoceptor binding in the lateral hypothalamus is reduced at dusk, together with reduction of food intake; alpha 2-adrenoceptor binding in the medial hypothalamus is increased at dawn, together with persistent food intake. Long-term changes in these two adrenergic systems are also correlated with homeostasis of food intake: 24-h mean beta-adrenoceptor binding is reduced and alpha 2-adrenoceptor binding is increased upon methamphetamine withdrawal, when rebound feeding occurs. Corticosterone, although normally coupled to adrenergic mechanisms that regulate feeding, is phase delayed after chronic methamphetamine treatment.