Feeding inhibition by urocortin in the rat hypothalamic paraventricular nucleus

Ventricular administration of urocortin (UCN) inhibits feeding, but specifi c site(s) of UCN action are unknown. In the current studies we examined the effect of UCN in the hypothalamic paraventricular nucleus (PVN) on feeding . We tested UCN administered into the PVN in several paradigms: deprivation -induced, nocturnal, and neuropeptide Y (NPY)-induced feeding. We compared the effect of equimolar doses of UCN and corticotrophin releasing hormone ( CRH) on NPY-induced and nocturnal feeding, determined whether UCN in the PV N produced a conditioned taste aversion (CTA) and induced changes in c-Fos immunoreactivity (c-Fos-ir) after UCN and NPY administration in the PVN. UC N in the PVN significantly decreased NPY and nocturnal and deprivation-indu ced feeding at doses of 1, 10, and 100 pmol, respectively. UCN anorectic ef fects lasted longer than those attributed to CRH. Ten and thirty picomoles UCN did not induce a CTA, whereas 100 pmol UCN produced a CTA. UCN (100 pmo l) in the PVN neither increased c-Fos-ir in any brain region assayed nor al tered c-Fos-ir patterns resulting from PVN NPY administration. These data s uggest the hypothalamic PVN as a site of UCN action.