Alterations in the Hippocampal Endocannabinoid System in Diet-Induced Obese Mice

Abstract The endocannabinoid system (ECS) is thought to be involved in obesity because its activation increases appetite and weight gain (Pagotto et al 2006). The ECS is hyperactivated in the hypothalamus of obese mice, and peripheral overactivation has been observed in humans; circulating 2-arachidonoyl glycerol (2-AG) levels positively correlated with body fat, visceral fat and fasting glucose (Osei-Hyiaman et al 2005) (Bluher et al 2006) (Motaghedi and McGraw 2008) (Cavuoto et al 2007) (Artmann et al 2008) (Bermudez-Silva 2009). The aim of this study was to evaluate whether differential activation of the peripheral versus the central ECS occurred in humans and to test the hypothesis that the ECS is hyperactivated in the human central nervous system (CNS).Cerebral spinal fluid (CSF) and blood samples were collected from 13 obese and 11 lean control women to measure 2-AG and anandamide (AEA) levels.AEA levels were higher in the plasma of obese women (obese: 4.03 ± 0.91 pmol/mL, N=13; lean: 1.84 ± 0.21 pmol/mL, N=10; p<0.05) but were lower in the CSF of obese women. The plasma/CSF ratio was 41.58 ± 5.78 (N=10) in lean women and 103.0 ± 37.36 (N=6) in obese women (p=0.054). There were no correlations between plasma and CSF AEA levels or with any biochemical parameter. The 2-AG analysis was not possible because of technical problems.Our data suggested that in human obesity, the peripheral ECS may be more active than the central ECS. Indeed, the system appeared to be suppressed in the CNS of obese women. Therefore, the peripheral activation of the ECS may be more relevant for obesity. Keywords: Anandamide, 2-arachidonoyl glycerol, obesity, endocannabinoid, endocannabinoid system, cb1 receptor.

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

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.648 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Jie Liu ◽

Grzegorz Godlewski ◽

Ziyi Liu ◽

Resat Cinar ◽

Keming Xiong ◽

...

Keyword(s):

Insulin Sensitivity ◽

Hepatic Steatosis ◽

Endocannabinoid System ◽

Current Data ◽

Metabolic Effects ◽

Fibroblast Growth Factor 21 ◽

Obese Mice ◽

Wild Type ◽

Peripheral Tissues ◽

Selective Blockade

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.

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Endocannabinoids Produced by White Adipose Tissue Modulate Lipolysis in Lean but Not in Obese Rodent and Human

Frontiers in Endocrinology ◽

10.3389/fendo.2021.716431 ◽

2021 ◽

Vol 12 ◽

Author(s):

Chloé Buch ◽

Tania Muller ◽

Julia Leemput ◽

Patricia Passilly-Degrace ◽

Pablo Ortega-Deballon ◽

...

Keyword(s):

Adipose Tissue ◽

White Adipose Tissue ◽

Endocannabinoid System ◽

Tissue Remodeling ◽

Obese Mice ◽

Glycerol Production ◽

Fat Mobilization ◽

Tissue Contents

White adipose tissue (WAT) possesses the endocannabinoid system (ECS) machinery and produces the two major endocannabinoids (ECs), arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG). Accumulating evidence indicates that WAT cannabinoid 1 receptors (CB1R) are involved in the regulation of fat storage, tissue remodeling and secretory functions but their role in controlling lipid mobilization is unclear. In the present study, we used different strategies to acutely increase ECS activity in WAT and tested the consequences on glycerol production as a marker of lipolysis. Treating lean mice or rat WAT explants with JLZ195, which inhibits ECs degrading enzymes, induced an increase in 2-AG tissue contents that was associated with a CB1R-dependent decrease in lipolysis. Direct treatment of rat WAT explants with AEA also inhibited glycerol production while mechanistic studies revealed it could result from the stimulation of Akt-signaling pathway. Interestingly, AEA treatment decreased lipolysis both in visceral and subcutaneous WAT collected on lean subjects suggesting that ECS also reduces fat store mobilization in Human. In obese mice, WAT content and secretion rate of ECs were higher than in control while glycerol production was reduced suggesting that over-produced ECs may inhibit lipolysis activating local CB1R. Strikingly, our data also reveal that acute CB1R blockade with Rimonabant did not modify lipolysis in vitro in obese mice and human explants nor in vivo in obese mice. Taken together, these data provide physiological evidence that activation of ECS in WAT, by limiting fat mobilization, may participate in the progressive tissue remodeling that could finally lead to organ dysfunction. The present findings also indicate that acute CB1R blockade is inefficient in regulating lipolysis in obese WAT and raise the possibility of an alteration of CB1R signaling in conditions of obesity.

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