Intermedin in paraventricular nucleus attenuates sympathetic activity and blood pressure via nitric oxide in hypertensive rats.
Intermedin (IMD) is a member of calcitonin/calcitonin gene-related peptide family, which shares the receptor system consisting of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs). This study investigated the effects of IMD in paraventricular nucleus (PVN) on renal sympathetic nerve activity and mean arterial pressure and its downstream mechanism in hypertension. Rats were subjected to 2-kidney 1-clip (2K1C) surgery to induce renovascular hypertension or sham operation. Acute experiments were performed 4 weeks later under anesthesia. IMD mRNA and protein were downregulated in 2K1C rats. Bilateral PVN microinjection of IMD caused greater decreases in renal sympathetic nerve activity and mean arterial pressure in 2K1C rats than in sham-operated rats, which were prevented by pretreatment with adrenomedullin receptor antagonist AM22-52 or nonselective nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester, and attenuated by selective neuronal NO synthase inhibitor N(ω)-propyl-l-arginine hydrochloride or endothelial NO synthase inhibitor N(5)-(1-iminoethyl)-l-ornithine dihydrochloride. AM22-52 increased renal sympathetic nerve activity and mean arterial pressure in 2K1C rats but not in sham-operated rats, whereas calcitonin/calcitonin gene-related peptide receptor antagonist calcitonin/calcitonin gene-related peptide 8-37 had no significant effect. CRLR and RAMP3 mRNA, as well as CRLR, RAMP2, and RAMP3 protein expressions, in the PVN were increased in 2K1C rats. Microinjection of IMD into the PVN increased the NO metabolites (NOx) level in the PVN in 2K1C rats, which was prevented by AM22-52. Chronic PVN infusion of IMD reduced, but AM22-52 increased, blood pressure in conscious 2K1C rats. These results indicate that IMD in the PVN inhibits sympathetic activity and attenuates hypertension in 2K1C rats, which are mediated by adrenomedullin receptors (CRLR/RAMP2 or CRLR/RAMP3) and its downstream NO.
Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, 140 Hanzhong Rd, Nanjing 210029, China. gqzhucn@njmu.edu.cn.
Ye-Bo
YB
Zhou
Hai-Jian
HJ
Sun
Dan
D
Chen
Tong-Yan
TY
Liu
Ying
Y
Han
Jue-Jin
JJ
Wang
Chao-Shu
CS
Tang
Yu-Ming
YM
Kang
Guo-Qing
GQ
Zhu
D053607:Adrenomedullin / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D058286:Calcitonin Receptor-Like Protein / Q000235:genetics; D006973:Hypertension / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000503:physiopathology; D008297:Male; D008916:Miotics / Q000494:pharmacology; D009479:Neuropeptides / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D058262:Receptor Activity-Modifying Protein 1 / Q000235:genetics; D058263:Receptor Activity-Modifying Protein 2 / Q000235:genetics; D058264:Receptor Activity-Modifying Protein 3 / Q000235:genetics; D058265:Receptors, Adrenomedullin / Q000037:antagonists & inhibitors; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
C499411:Adm2 protein, rat; D058286:Calcitonin Receptor-Like Protein; D008916:Miotics; D009479:Neuropeptides; D010446:Peptide Fragments; D012333:RNA, Messenger; C545508:Ramp1 protein, rat; C545509:Ramp2 protein, rat; C545510:Ramp3 protein, rat; D058262:Receptor Activity-Modifying Protein 1; D058263:Receptor Activity-Modifying Protein 2; D058264:Receptor Activity-Modifying Protein 3; D058265:Receptors, Adrenomedullin; C104782:adrenomedullin (22-52); C058636:calcitonin gene-related peptide (8-37); D053607:Adrenomedullin; D009569:Nitric Oxide; D015740:Calcitonin Gene-Related Peptide
hypertension; intermedin protein, rat; nitric oxide; paraventricular hypothalamic nucleus