347-OR: Methionine Restriction Differentially Protects against High-Fat Diet-Induced Neuroinflammation and Central Insulin Resistance in Male and Female Mice

Abstract

High-fat diets (HFD) promote central inflammation and insulin resistance (IR). Methionine restriction (MR) improves peripheral insulin sensitivity, lipid metabolism, and cognitive function, at least in part by increasing fibroblast growth factor 21 (FGF21). However, the ability of MR to protect against neuroinflammation and central IR during adolescence has not been examined. Moreover, whether MR depends on FGF21 to protect against HFD-induced changes in central insulin signaling or neuroinflammation is unknown. We sought to determine whether MR protects against HFD-induced neuroinflammation and central IR during adolescence in males and females and whether MR’s effects are dependent on FGF21. Male and female wild-type (WT) and FGF21 knockout (KO) mice, aged 5 to 6 wk, were fed normal (18.9% fat-derived kcal) or high-fat (60% fat-derived kcal) versions of control (0.86% methionine) or MR (0.17% methionine) diets for 5 wk. To investigate insulin action, ITTs were performed after 4 wk on the diet, and saline or insulin (0.6U/kg body weight) was administered 15 min prior to sacrifice. MR significantly decreased weight gain of HFD-fed mice regardless of sex or genotype (p < 0.05). MR increased serum FGF21 of all males and HFD-fed females (p < 0.05), and strongly tended to increase FGF21 in female mice on the normal-fat diet. HFD feeding tended to promote inflammatory gene expression in the hippocampus of WT males, while MR trended to mitigate inflammation independent of FGF21. MR also significantly reduced fasting blood glucose and improved peripheral insulin response in an FGF21-dependent fashion (p < 0.05). Though, neither HFD nor MR had a notable impact on markers of IR in the hypothalamus or hippocampus. Our findings indicate that short-term MR improves metabolic parameters of adolescent mice fed normal or high-fat diets. In addition, MR acts in an FGF21-independent and sex-dependent manner to improve neuroinflammation. Disclosure H.L.Lail: None. R.Lawrence: None. D.Wanders: None.