Altered expression of FosB/ΔFosB in central autonomic regions in hypertensive obese Zucker rats

Abstract

Adult obese Zucker rats (OZR) have elevated sympathetic nerve activity and blood pressure vs. lean Zucker rats (LZR). We determined whether autonomic regulatory regions in the brain are chronically activated in OZR vs. LZR by immunohistochemical examination of FosB/ΔFosB expression. Male rats (14 wks) were perfused with paraformaldehyde and brains were sectioned coronally. One in six sections were processed for FosB expression (Santa Cruz goat anti‐FosB) via a nickel diaminobenzidine (DAB) reaction. A subset was processed to reveal catecholaminergic neurons (Chemicon mouse anti‐tyrosine hydroxylase) via a DAB reaction. In nucleus tractus solitarius (−13.1 to −13.5 mm bregma) FosB expression was higher (85–134%) in OZR (7) vs. LZR (6) at all levels. In rostral ventrolateral medulla (−12.0 to −12.6 mm bregma) FosB expression was enhanced at the most caudal level (−12.6 mm) in OZR with comparable expression in other levels in OZR (5) vs. LZR (5). In NTS and RVLM there was no FosB expression in catecholaminergic neurons in OZR or LZR. In the hypothalamic paraventricular nucleus (PVN) OZR (5) had less FosB expression (94–200%) vs. LZR (5). Similarly, in the anterior hypothalamic nucleus OZR(6) had less (18–44%) expression than LZR(6). These data suggest that the chronic activations of multiple autonomic regions are altered in OZR vs. LZR, and future studies are needed to identify the phenotypes of the activated neurons.