Vasopressin Gene Expression is Differently Regulated at the PVN Level of Salt‐loaded Wistar and SHR

Abstract

It is known that osmotic challenges leads to an increase in blood pressure that is associate with a simpathoexcitatory component; moreover, the paraventricular nucleus of hypothalamus (PVN) plays an important role in this response. Previous studies performed in our lab have shown that salt‐induced sympathoexcitation and hypertension involves arginine vasopressin (AVP) receptors activation at the PVN level. Thus, here we sought to evaluate if the high salt‐induced hypertension could be due a differential AVP mRNA expression into the PVN of SHR and Wistar. Institutional approved ethical committee protocol N° 111‐ Male SHR and Wistar (300 g). Were offered NaCl 2% in replacement of the drinking water, and kept in metabolic cages for 1, 4 or 7 days to evaluate hydroelectrolytic parameters. At the end, the animals were decapitated and the PVN was microdissected for RNA extraction and qPCR procedures. The results have shown a higher increase in the blood pressure (194±8 mmHg, n=3) in SHR exposed to 7 days of high salt intake when compared to 7 days salt‐loaded Wistars (131±4 mmHg, n=4). An upregulation of AVP gene expression in the PVN was observed only in SHR rats subjected to salt overload for 7 days (2,7±0,53 a.u, n=7) compared to the their normohydrated control group (0,86 ± 0,3, n=6) and Wistar animals exposure to the same period to salt overload (1,6±0,2 a.u, n=7). In conclusion, we can suggest that AVP mRNA expression in the PVN of salt‐loaded animals is time‐dependent and differently modulated in Wistar and SHR, which could be a causality relationship with higher blood pressure levels observed in salt‐loaded SHR.