REN and hypertensive disorder: It is well known that hypertension, a low-grade inflammatory disease, is accompanied by upregulation of the renin–angiotensin system, dysfunctional blood–brain barrier (BBB) permeability, and resident microglia activation within autonomic brain areas, allowing the autonomic imbalance that maintains high vasomotor sympathetic activity and pressure elevation (Guyenet, 2006; Biancardi et al., 2014; Shen et al., 2015; Buttler et al., 2017; Forrester et al., 2018; Su et al., 2021; Wang et al., 2022).