The effect of cocaine-amphetamine regulated transcript (CART) on the activation of the pituitary-adrenal axis

OBJECTIVE: It has been reported that the cocaine and amphetamine regulated transcript (CART) is widely expressed in the hypothalamic nuclei involved in the mechanism of hormonal secretion. RESEARCH METHODS: In order to evaluate the effect of CART on the activation of the pituitary-adrenal axis in the rat, CART (55-102) in a dose of 0.5 mu g in 5 mu l CSF was infused into the third ventricle (icv) with an automatic pump. At 10, 30, 60, 120 min after the infusion of CART or vehicle, the animals were decapitated and the trunk blood was collected. Serum ACTH and corticosterone concentrations were measured with RIA kits provided by Phoenix Pharmaceuticals and ICN Biomedicals USA, respectively. RESULTS: The stimulating effect of CART on ACTH concentration was observed only 30 min after icv injection. However, CART stimulated corticosterone release at 10, 30, 60 min after icv injection. CONCLUSIONS: CART (55-102) administered intracerebroventricularly (icv) stimulated ACTH and corticosterone release. The stimulating effect of CART on ACTH was short-lived.