Role of microglia M1/M2 polarisation in the paraventricular nucleus: New insight into the development of stress-induced hypertension in rats

The lack of precise therapies for stress-induced hypertension highlights the need to explore the process of blood pressure changes. Studies have shown that neuroinflammation in the central nervous system is associated with hypertension, although the mechanisms remain elusive. Microglia, are known to play dualistic protective and destructive roles, representing logical but challenging targets for improving stress-induced hypertension. Here, as a model, we used rats with stress-induced hypertension, and found that a switch from an immunoregulatory (M2) to a pro-inflammatory (M1) dominant response occurred in microglia during development of stress-induced hypertension. Administration of minocycline, which is commonly used to inhibit microglial M1 polarisation, attenuated the increase in activated microglia and M1 microglial markers expression in the hypothalamic paraventricular nucleus of rats with stress-induced hypertension. To shed further light on development of stress-induced hypertension, we examined changes in pro- and anti-inflammatory cytokines, and found increased expression of M2 microglial markers during early pathogenesis. Based on these results, we propose the possibility that M1/M2 microglia are related to development of stress-induced hypertension. Consequently, a target molecule that skews M2 polarisation of microglia may be a beneficial therapy for this disease.