Brain angiotensins levels in hypertension and aging

CERNIELLO FM; SIRRI MF; CARRETERO OA; GIRONACCI MM

Congreso; Inter-American Society of Hypertension Meeting 2017; 2017

The depressor axis of the renin-angiotensin system (RAS) exerts cerebroprotective effects. We hypothetized that a centrally dysbalance exists between both axis that may contribute to hypertension development and cognitive dysfunction with age. Our aim was to determine Ang-(1-7) and Ang II levels in different areas of the brain in normotensive and spontaneously hypertensive (SHR) rats of different ages. Hypothalamus (HT), brain stem (BS), hippocampus (HC) and brain cortex (C) from 1, 3 and 12-months-old rats were isolated. Ang levels were quantified by radioimmunoassay. Ang-(1-7) levels decreased with age in HT, BS and C from normotensive rats. Regarding SHR, an increase in Ang-(1-7) levels with age was observed in BS, HC and HT when 1 and 3 months-old rats were compared but not significant differences were observed between 3 and 12 months-old rats, except in brainstem where Ang-(1-7) decreased. Ang-(1-7) levels in C did not significantly change with age in SHR. In all the studied areas Ang-(1-7) levels in 1-month-old rats were greater in normotensive than in SHR. Ang II levels increased with age in all the studied areas both in normotensive and SHR. However, AngII levels in HT, BS and C of 12-months-old rats decreased in comparison to 3-months-old rats. 1-month-old SHR showed greater Ang II levels in BS and C in comparison to normotensive young rats. On the contrary, Ang II levels in HT of young SHR were lower than in normotensive. Our results show that brain Ang-(1-7) levels in normotensive rats decreased while Ang II levels increased with age. The fact that Ang-(1-7) increased with age in hypertension may be due to a compensatory mechanism.