SUN-665 Peripheral CB1R Blocker Improves Metabolism in Diet Induced Obese Mice Independent of Hepatic FGF21

Abstract

Obesity is associated with an overactive endocannabinoid system, and selective blockade of CB1R in peripheral tissues, including the liver, reverses HFD-induced metabolic abnormalities by restoring normal lipid and glucose homeostasis. Fibroblast growth factor-21 (FGF21) has emerged as a major endocrine regulator derived from the liver that reduces adiposity and hepatic steatosis and improves glucose tolerance and insulin sensitivity, with changes similar to those induced by CB1R blockade. Here we investigated whether FGF21 mediate the metabolic effects of CB1R blockade in DIO mice.In C57BL/6J wild-type mice, HFD caused a robust increase in hepatic Fgf21 mRNA and serum FGF21 levels, which were reversed by chronic CB1R blockade to levels observed in STD or vehicle-treated hepatocyte-specific CB1R-/- (LCB1-/-) mice, indicating activation of CB1R in the liver is largely involved in HFD-induced “FGF21-resistant” state. In contrast, the expression of the FGF21 receptor Fgfr1 and co-receptor β-klotho (Klb) were dramatically reduced by HFD in both epididymal fat and brain tissue in wild-type mice, and these effects were reversed by peripheral CB1R antagonist JD5037 treatment.To address whether FGF21 mediated the metabolic effects of CB1R blockade, we repeated JD5037 treatment in liver-specific FGF21-/- (FGF21-LKO) mice. Surprisingly, JD5037 treatment was almost equally effective in both HFD-fed wild-type and in FGF21-LKO mice in reducing body weight and hepatic steatosis, attenuating hyperinsulinemia and hyperleptinemia. The current data suggest that peripheral CB1R blockade in obese mice improves insulin sensitivity and energy expenditure independently of hepatic FGF21.