Increasing hypothalamic nucleobindin 2 levels and decreasing hypothalamic inflammation in obese male mice via diet and exercise alleviate obesity-associated hypogonadism

Abstract

To explore the role of nesfatin-1 in regulating male reproductive function during energy balance variation, we employed an obese mouse model which was first induced by a high-fat diet (HFD) and followed by interventions of a normal diet (ND) and/or moderate exercise, and then serum reproductive hormones of male mice, hypothalamic nucleobindin 2 (NUCB2)/nesfatin-1, inflammatory factors, and gonadotropin-releasing hormone (GnRH) levels were tested. Our findings showed that both serum nesfatin-1, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) levels and hypothalamic NUCB2/nesfatin-1 and Gnrh mRNA levels were reduced, whereas, the mRNA and protein levels of hypothalamic tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, inhibitor kappa B kinase β (IKKβ), and nuclear factor (NF)-κB were increased in obese male mice. Diet, exercise, and diet combined with exercise interventions reversed the decreases in serum nesfatin-1, FSH, LH, and T levels; increased hypothalamic NUCB2/nesfatin-1 and Gnrh mRNA levels; and reduced hypothalamic TNF-α, IL-1β, IKKβ, and NF-κB levels. These changes were accompanied by reduced adiposity, and these effects were more obvious in the diet combined with exercise group. Overall, our findings suggested that the hypogonadotropic hypogonadism associated with obesity may be induced by reduced hypothalamic NUCB2/nesfatin-1 levels, which attenuated the stimulatory effect on GnRH directly or indirectly by suppressing its anti-inflammatory effect in the brain. Diet and/or exercise interventions were able to alleviate the hypogonadotropic hypogonadism associated with obesity, potentially by increasing hypothalamic NUCB2/nesfatin-1 levels.