Nrf2 Improves Leptin and Insulin Resistance Provoked by Hypothalamic Oxidative Stress

Abstract

The relationship between loss of hypothalamic function and onset of diabetes mellitus remains elusive. Therefore, we generated a targeted oxidative-stress murine model utilizing conditional knockout (KO) of selenocysteine-tRNA (Trsp) using rat-insulin-promoter-driven-Cre (RIP-Cre). These Trsp-KO (Trsp^RIPKO) mice exhibit deletion of Trsp in both hypothalamic cells and pancreatic β cells, leading to increased hypothalamic oxidative stress and severe insulin resistance. Leptin signals are suppressed, and numbers of proopiomelanocortin-positive neurons in the hypothalamus are decreased. In contrast, Trsp-KO mice (Trsp^Ins1KO) expressing Cre specifically in pancreatic β cells, but not in the hypothalamus, do not display insulin and leptin resistance, demonstrating a critical role of the hypothalamus in the onset of diabetes mellitus. Nrf2 (NF-E2-related factor 2) regulates antioxidant gene expression. Increased Nrf2 signaling suppresses hypothalamic oxidative stress and improves insulin and leptin resistance in Trsp^RIPKO mice. Thus, Nrf2 harbors the potential to prevent the onset of diabetic mellitus by reducing hypothalamic oxidative damage.

Keywords: Nrf2; Trsp; hypothalamus; insulin resistance; leptin resistance; oxidative stress; pancreatic beta-cells; proopiomelanocortin; selenoproteins.