title: cAMP/PKA Agonist Restores the Fasting-Induced Down-Regulation of nNOS Expression in the Paraventricular Nucleus.
abstract: Gene expression of neuronal nitric oxide synthase (nNOS) changes in the hypothalamic paraventricular nucleus (PVN) depending on feeding conditions, which is decreased during food deprivation and restored by refeeding, and phosphorylated cAMP response element binding protein (pCREB) was suggested to play a role in its regulation. This study was conducted to examine if the fasting-induced down-regulation of the PVN-nNOS expression is restored by activation of cAMP-dependent protein kinase A (cAMP/PKA) pathway. Freely moving rats received intracerebroventricular (icv) injection of cAMP/PKA activator Sp-cAMP (40 nmol) or vehicle (sterilized saline) following 48 h of food deprivation. One hour after drug injections, rats were transcardially perfused with 4% paraformaldehyde, and the PVN tissues were processed for nNOS or pCREB immunohistochemistry. Sp-cAMP significantly increased not only nNOS but also pCREB immunoreactivities in the PVN of food deprived rats. Fasting-induced down-regulation of the PVN-nNOS was restored by 1 h after the icv Sp-cAMP. Results suggest that cAMP/PKA pathway may mediate the regulation of the PVN-nNOS expression depending on different feeding conditions.
authors.affiliation: Dental Research Institute, Department of Oral & Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul 110-768, Korea.
authors.forename: Sang Bae
authors.initials: SB
authors.lastname: Yoo
authors.forename: Seoul
authors.initials: S
authors.lastname: Lee
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Bom-Taeck
authors.initials: BT
authors.lastname: Kim
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Jeong Won
authors.initials: JW
authors.lastname: Jahng
keywords: Food deprivation; Gene expression; Neuronal nitric oxide synthase; Paraventricular nucleus; Rat