Work

Negative Regulation of Leptin-induced Reactive Oxygen Species (ROS) Formation by Cannabinoid CB1 Receptor Activation in Hypothalamic Neurons

Year: 2015

Type: article

Abstract: The adipocyte-derived, anorectic hormone leptin was recently shown to owe part of its regulatory effects on appetite-regulating hypothalamic neuropeptides to the elevation of reactive oxygen species (ROS) levels in arcuate nucleus (ARC) neurons. Leptin is also known to exert a negative regulation on hypothalamic endocannabinoid levels and hence on cannabinoid CB 1 receptor activity. Here we investigated the possibility of a negative regulation by CB 1 receptors of leptin-mediated ROS formation in the ARC. Through pharmacological and molecular biology experiments we report data showing that leptin-induced ROS accumulation is 1) blunted by arachidonyl-2′-chloroethylamide (ACEA) in a CB 1 -dependent manner in both the mouse hypothalamic cell line mHypoE-N41 and ARC neuron primary cultures, 2) likewise blocked by a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, troglitazone, in a manner inhibited by T0070907, a PPAR-γ antagonist that also inhibited the ACEA effect on leptin, 3) blunted under conditions of increased endocannabinoid tone due to either pharmacological or genetic inhibition of endocannabinoid degradation in mHypoE-N41 and primary ARC neuronal cultures from MAGL −/− mice, respectively, and 4) associated with reduction of both PPAR-γ and catalase activity, which are reversed by both ACEA and troglitazone. We conclude that CB 1 activation reverses leptin-induced ROS formation and hence possibly some of the ROS-mediated effects of the hormone by preventing PPAR-γ inhibition by leptin, with subsequent increase of catalase activity. This mechanism might underlie in part CB1 orexigenic actions under physiopathological conditions accompanied by elevated hypothalamic endocannabinoid levels. Background: In hypothalamic neurons, leptin induces ROS production via PPAR-γ inhibition. Results: CB1 agonism prevents leptin-induced ROS accumulation by reversing PPAR-γ and catalase inhibition. Inhibition of endocannabinoid inactivation also counteracts leptin effects. Conclusion: CB 1 inhibits effects of leptin that underlie part of its anorexic actions. Significance: During conditions of increased endocannabinoid tone CB 1 might reduce leptin activity in the hypothalamus.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m115.646885