Peripheral cannabinoid-1 receptor blockade restores hypothalamic leptin signaling

Area of Science:

• Neuroscience
• Endocrinology
• Obesity Research

Background:

• Visceral obesity involves an overactive endocannabinoid/CB1 receptor (CB1R) system, increasing caloric intake and decreasing energy expenditure.
• Peripheral CB1R blockade mitigates these effects, and JD5037 inhibits food intake in diet-induced obesity (DIO) mice by reversing hyperleptinemia and leptin resistance.

Purpose of the Study:

• To investigate the hypothalamic signaling pathway engaged by leptin after chronic treatment with the CB1R antagonist JD5037 in DIO mice.
• To elucidate how peripheral CB1R blockade restores leptin sensitivity and reduces food intake.

Main Methods:

• Analysis of hypothalamic circuitry in DIO mice chronically treated with JD5037.
• Assessment of STAT3 phosphorylation in arcuate nucleus (ARC) neurons following leptin treatment or fasting/refeeding.
• Evaluation of the hypophagic effect of JD5037 in melanocortin-4 receptor (MC4R) deficient or NPY knockout mice.

Main Results:

• Leptin induced STAT3 phosphorylation in ARC neurons of lean and JD5037-treated DIO mice, but not vehicle-treated DIO mice.
• pSTAT3 co-localization was less frequent with NPY+ than POMC+ ARC neurons.
• The hypophagic effect of JD5037 was abolished in MC4R-deficient or MC4R-antagonist-treated mice but maintained in NPY-/- mice.

Conclusions:

• Peripheral CB1R blockade in DIO mice restores sensitivity to endogenous leptin.
• Leptin elicits hypophagia through the re-activation of melanocortin signaling in the ARC.
• This pathway involves POMC neurons and MC4R signaling, independent of NPY.