Hypertensive background modifies central nervous system stress responses in male rats

Abstract

Hypertension is a risk factor for stroke, and has been correlated with HPA axis sensitization and the initiation of immune/inflammatory processes during chronic stress. Our study examined whether hypertension affects the stress‐induced activation of brain regions involved in the generation of stress responses and cardiovascular control. Spontaneously hypertensive (SHR) and normotensive Wistar‐Kyoto (WKY) male rats were acutely (30min x 1d) or repeatedly (30min x 14d) restrained or were not stressed. Perfused brain sections were immunohistochemically stained for Fos, which was quantified in the paraventricular (PVH) and dorsomedial (DMH) nuclei and the central (CeA) and medial (MeA) amygdala. Acute stress increased Fos in the PVH and DMH of WKY rats, compared to controls, and this response habituated with repeated stress exposure. Similar results were seen in control and acute SHRs, but the habituation of Fos induction was not seen in the PVH and only partially occurred in the DMH of these animals after repeated stress. MeA and CeA responses varied by stress treatment but were largely similar in the two strains. The data suggest that hypertension leads to enhanced responses to chronic stress at the level of neuronal activation. Understanding stress‐hypertension interactions in the central nervous system will aid the development of treatments for these and related conditions. Support: NIH 5G12 RR008124