ROLE OF ENDOTHE LIN RECEPTOR TYPE A (ETA) IN THE ACTIVITY AND EXPRESSION OF TYROSINE HYDROXYLASE (TH) IN THE ANTERIOR (AH) AND POSTERIOR HYPOTHALAMUS (PH) OF DOCA - SALT HYPERTENSIVE RATS

GUIL M.; CASSINOTTI L.; BALABASQUER L.; CATANZARITI A.; BIANCIOTTI L.; VATTA M.

Congreso; 1st PanAmerican Congress of Physiological Sciences; 2014

We previously reported that the chatecholaminergic system is impaired in PH and AH of DOCA-salt hypertensive rats. Furthermore, these regions exposed to exogenous ETs exhibit changes in the noradrenergic activity but only in hypertensive animals. In the present study, we aimed to determine the role of brain ETA receptors in TH activity and expression in the AH and PH of DOCA-salt hypertensive rats. A guide cannula was placed in the brain lateral ventricle of DOCA-salt hypertensive rats and BQ610 (ETA receptor antagonist) was injected. Blood pressure (BP) was recorded for 60 min and hypothalamus dissected in posterior and anterior areas to determine TH activity and expression as well as the enzyme-phosphorylated forms by radioenzymatic and western blot assays. BQ610 strongly reduced blood pressure but did not affect TH activity and expression in the AH of either hypertensive or normotensive rats. However, the ETA antagonist reduced TH expression and its phosphorylation at 40Ser site in the PH in hypertensive animals. These findings show that ETA receptor blockade reduces noradrenergic activity in a well-known sympatho-excitatory area like the PH, supporting that ETs through the activation of this receptor subtype leads to blood pressure elevation in this animal model of hypertension.