Functional characterizations of cocaine- and amphetamine-regulated transcript mRNA expression in rat hypothalamus.

Anatomical relationships of hypothalamic cocaine- and amphetamine-regulated transcript (CART) with other hypothalamic neuropeptides were examined by using in situ hybridization histochemistry and immunohistochemistry. CART mRNA was found in various regions in rat hypothalamus, including the periventricular nucleus, paraventricular nucleus, dorsomedial nucleus, perifornical regions, lateral nucleus, and the arcuate nucleus. In the paraventricular nucleus, CART mRNA is colocalized with vasopressin and corticotropin-releasing factor-containing neurons. Moreover, either fasting or diabetes attenuates CART mRNA expression in the hypothalamus, demonstrating that CART mRNA regulation is related to the fuel availability and peripheral hormonal status. Our findings suggest that the presence of CART mRNA in specific cell groups of the hypothalamus plays a role in hypothalamic regulation of neuroendocrine functions.