title: Angiotensin-(1-7) in paraventricular nucleus modulates sympathetic activity and cardiac sympathetic afferent reflex in renovascular hypertensive rats.
abstract: BACKGROUND
  Excessive sympathetic activity contributes to the pathogenesis and progression of hypertension. Enhanced cardiac sympathetic afferent reflex (CSAR) is involved in sympathetic activation. This study was designed to determine the roles of angiotensin (Ang)-(1-7) in paraventricular nucleus (PVN) in modulating sympathetic activity and CSAR and its signal pathway in renovascular hypertension.
  
  
  RESULTS
  Renovascular hypertension was induced with two-kidney, one-clip method. Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in sinoaortic-denervated and cervical-vagotomized rats with anesthesia. CSAR was evaluated with the RSNA and MAP responses to epicardial application of capsaicin. PVN microinjection of Ang-(1-7) and cAMP analogue db-cAMP caused greater increases in RSNA and MAP, and enhancement in CSAR in hypertensive rats than in sham-operated rats, while Mas receptor antagonist A-779 produced opposite effects. There was no significant difference in the angiotensin-converting enzyme 2 (ACE2) activity and Ang-(1-7) level in the PVN between sham-operated rats and hypertensive rats, but the Mas receptor protein expression in the PVN was increased in hypertensive rats. The effects of Ang-(1-7) were abolished by A-779, adenylyl cyclase inhibitor SQ22536 or protein kinase A (PKA) inhibitor Rp-cAMP. SQ22536 or Rp-cAMP reduced RSNA and MAP in hypertensive rats, and attenuated the CSAR in both sham-operated and hypertensive rats.
  
  
  CONCLUSIONS
  Ang-(1-7) in the PVN increases RSNA and MAP and enhances the CSAR, which is mediated by Mas receptors. Endogenous Ang-(1-7) and Mas receptors contribute to the enhanced sympathetic outflow and CSAR in renovascular hypertension. A cAMP-PKA pathway is involved in the effects of Ang-(1-7) in the PVN.
authors.affiliation: Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Han
authors.forename: Hai-Jian
authors.initials: HJ
authors.lastname: Sun
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Qing
authors.initials: Q
authors.lastname: Gao
authors.forename: Ye-bo
authors.initials: YB
authors.lastname: Zhou
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Xing-Ya
authors.initials: XY
authors.lastname: Gao
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Zhu
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000344:Afferent Pathways / Q000187:drug effects / Q000503:physiopathology*; D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000031:analogs & derivatives / Q000494:pharmacology; D000085962:Angiotensin-Converting Enzyme 2; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000294:innervation* / Q000503:physiopathology; D006978:Hypertension, Renovascular / Q000473:pathology / Q000503:physiopathology*; D007668:Kidney / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D008297:Male; D008845:Microinjections; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D010446:Peptide Fragments / Q000494:pharmacology*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012018:Reflex / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: C092006:7-Ala-angiotensin (1-7); D010446:Peptide Fragments; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D013873:Thionucleotides; D000804:Angiotensin II; C017759:9-(tetrahydro-2-furyl)-adenine; C016957:adenosine-3',5'-cyclic phosphorothioate; D003994:Bucladesine; D000803:Angiotensin I; D000242:Cyclic AMP; D007703:Peptidyl-Dipeptidase A; C000705329:Ace2 protein, rat; D000085962:Angiotensin-Converting Enzyme 2; C118790:angiotensin I (1-7); D000225:Adenine