Evidence of specific inflammatory condition in nucleus tractus solitarii of spontaneously hypertensive rats

Abstract

Since the nucleus tractus solitarii (NTS) is a pivotal region for regulating the set-point of arterial pressure, we proposed a role for it in the development of neurogenic hypertension. Recent studies have suggested that proinflammatory molecules, such as junctional adhesion molecule 1 (JAM-1) are highly expressed in the NTS of an animal model of human essential hypertension, the spontaneously hypertensive rat (SHR), compared with normotensive rats (Wistar-Kyoto, WKY). Moreover, we have also shown endogenous leukocyte accumulation inside capillaries within the NTS of SHR but not WKY rats. Based on this evidence, we hypothesized that gene expression of cytokines/chemokines is altered in the NTS of SHR. We have screened for abnormally expressed inflammatory mediators in the NTS of SHR using the RT2 Profiler PCR arrays, which were designed specifically to target major cytokines/chemokines. The specific PCR array revealed that seven genes were less expressed in the NTS of SHR compared with WKY rats (more than twofold differences), while only two genes were more expressed in the SHR. Moreover, we identified that some of these validated molecules exhibit important functional roles for cardiovascular homeostasis at the level of the NTS. We suggest that abnormal gene expression of proinflammatory molecules, such as JAM-1, causes leukocyte accumulation within the vasculature in the NTS of SHR. Consequently, gene expression of specific cytokines/chemokines may be downregulated to avoid further strong inflammatory activity in the NTS of SHR at the expense of an alteration in neuronal activity that leads to cardiovascular autonomic pathology. Importantly, to allow translation of our work, these novel insights need to be assessed in hypertensive human brainstem tissue; their confirmation could lead to novel therapeutic approaches for one of the world's most prevalent diseases.