Involvement Of POMC Neurons In LEAP2 Regulation Of Food Intake And Body Weight

Background:Liver-expressed antimicrobial peptide 2（LEAP2）is a newly discovered antagonist or inverse agonist of the growth hormone secretagogue receptor（GHSR）and is considered the first endogenous peptide that can antagonize the metabolic actions of ghrelin.The effects of ghrelin administration on feeding behavior,body weight,and energy metabolism involve the activation of orexigenic neurons in the arcuate nucleus（ARC）of the hypothalamus.Objective:It is unclear if LEAP2 applied directly to the ARC of the hypothalamus affects these metabolic processes.This study explores the role of LEAP2 in the regulation of food intake,body weight,and energy balance,and further explores the relevant mechanisms,in order to provide new ideas to combat obesity and its associated diseases.Methods:1.AAV-GFP or AAV-LEAP2 were injected into the hypothalamic ARC of wild-type（WT）mice fed a chow diet.Food intake,body weight,and other indicators for energy metabolism were monitored in these two groups of mice.2.Mice infected with AAV-GFP or AAV-LEAP2 in the ARC were implanted with osmotic mini-pumps for 14-day central and peripheral continuous infusion of acyl-ghrelin.Food intake and body weight were measured daily for 13 days following pump implantation.3.The effects of adeno-associated virus（AAV）-mediated overexpression of LEAP2 in the ARC of WT mice under the metabolic condition of high-fat diet（HFD）feeding were investigated as in the virus-injected and chow-fed mice.4.Quantitative real-time PCR（q RT-PCR）and western blot were used to examine the effects of LEAP2 overexpression and diet on the hypothalamic agouti-related peptide（AGRP）/neuropeptide Y（NPY）,proopiomelanocortin（POMC）,and GHSR levels.5.Food intake and body weight were investigated after administration of LEAP2 peptide into the third ventricle by a guide cannula.6.The effect of LEAP2 on POMC neuronal activity was evaluated by c-Fos immunofluorescence staining and calcium imaging in vitro.7.The chemogenetic method was performed to determine whether POMC neurons are required to mediate LEAP2’s effect on food intake.Results:1.Overexpression of LEAP2 in the ARC by AAV reduced food intake and body weight gain in WT mice fed a chow diet.2.LEAP2 overexpression in the ARC overrides both central and peripheral ghrelin administration-induced food intake and body weight gain on a chow diet.3.Overexpression of LEAP2 in the ARC by AAV reduced food intake and body weight gain in WT mice fed a HFD and improved metabolic disorders in these diet-induced obese mice.4.AAV-LEAP2 treatment in the ARC increased POMC expression while AGRP/NPY and GHSR levels remained unchanged in the hypothalamus.5.Intracerebroventricular（i.c.v.）administration of LEAP2 decreased food intake,and repeated LEAP2 administration to mice induced body weight loss.6.Intracerebroventricular administration of LEAP2 increased c-Fos expression in POMC neurons in the ARC.In addition,LEAP2 application to ARC-containing sections increased Ca²⁺concentration in POMC neurons.7.Chemogenetic inhibition of POMC neurons abolished the anorexigenic effect of LEAP2.Conclusion:These results demonstrate that central delivery of LEAP2 leads to appetite-suppressing and body weight reduction,and regulates energy balance,which might require activation of POMC neurons in the ARC.This suggests LEAP2 may be an important target of obesity through influences on eating behavior.