Salt-induced sympathoexcitation involves vasopressin V-1a receptor activation in the paraventricular nucleus of the hypothalamus

Author(s)

Ribeiro, Natalia ^[1] ; Panizza, Helena do Nascimento ^[1] ; dos Santos, Karoline Martins ^[1] ; Ferreira-Neto, Hildebrando C. ^[1] ; Antunes, Vagner Roberto ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY; v. 309, n. 11, p. R1369-R1379, DEC 1 2015.
• Web of Science Citations: 10

Abstract

A high-salt diet can lead to hydromineral imbalance and increases in plasma sodium and osmolality. It is recognized as one of the major contributing factors for cardiovascular diseases such as hypertension. The paraventricular nucleus (PVN) plays a pivotal role in osmotically driven sympathoexcitation and high blood pressure, the precise mechanisms of which are not fully understood. Recent evidence indicates that AVP released from magnocellular neurons might be involved in this process. Using a combination of in vivo and in situ studies, we sought to investigate whether AVP, acting on PVN neurons, can change mean arterial pressure (MAP) and sympathetic nerve activity (SNA) in euhydrated male rats. Furthermore, we wanted to determine whether V-1a receptors on PVN neurons would be involved in salt-induced sympathoexcitation and hypertension. In rats, 4 days of salt loading (NaCl 2%) elicited a significant increase in plasma osmolality (39 +/- 7 mosmol/kgH(2)O), an increase in MAP (26 +/- 2 mmHg, P < 0.001), and sympathoexcitation compared with euhydrated rats. Microinjection of AVP into the PVN of conscious euhydrated animals (100 nl, 3 mu M) elicited a pressor response (14 +/- 2 mmHg) and a significant increase in lumbar SNA (100 nl, 1 mM) (19 +/- 5%). Pretreatment with a V-1a receptor antagonist, microinjected bilaterally into the PVN of salt-loaded animals, elicited a decrease in lumbar SNA (-14 +/- 5%) and MAP (-19 +/- 5 mmHg), when compared with the euhydrated group. Our findings show that AVP plays an important role in modulating the salt-induced sympathoexcitation and high blood pressure, via V-1a receptors, within the PVN of male rats. As such, V-1a receptors in the PVN might contribute to neurogenic hypertension in individuals consuming a high-salt diet. (AU)

• FAPESP's process: 09/13047-0 - Role of the autonomic nervous system in the hepatic production of glucose via central action of insulin in hypertensive animals
• Grantee: Izabela Martina Ramos Ribeiro de Toledo
• Support type: Scholarships in Brazil - Master
• FAPESP's process: 13/06206-0 - Gene expression changes of neuropeptides and proinflammatory factors of the hypothalamus and brainstem nucleus involved with cardiovascular regulation in diet-induced obesity animals
• Grantee: Vagner Roberto Antunes
• Support type: Regular Research Grants
• FAPESP's process: 10/17997-0 - Purinergic mechanisms at the hypothalamus level on sympathetic outflow and its correlation to neurogenic hypertension
• Grantee: Vagner Roberto Antunes
• Support type: Regular Research Grants
• FAPESP's process: 10/05037-1 - Role of purinergic receptors of paraventricular nucleus of the hypothalamus in the neurogenic hypertension
• Grantee: Hildebrando Candido Ferreira Neto
• Support type: Scholarships in Brazil - Doctorate