Liraglutide induces enhanced suppression of food intake in mice lacking the growth hormone secretagogue receptor

Abstract

The glucagon-like peptide-1 receptor (GLP-1R) and the growth hormone secretagogue receptor (GHSR) exert opposing effects on food intake. GLP-1R activation produces potent appetite-suppressing effects, whereas GHSR activation strongly stimulates food intake. Here, we tested the hypothesis that blocking GHSR could affect the anorectic and weight-reducing effects of liraglutide, a GLP-1R agonist widely used to treat diabetes and obesity. We first found that liraglutide induced a stronger reduction in food intake in ad libitum-fed GHSR-deficient mice compared to wild-type (WT) controls, regardless of sex. Liraglutide treatment also resulted in greater gastric content mass in ad libitum-fed GHSR-deficient mice than in WT mice. Interestingly, GLP-1R immunolabeling was elevated in the paraventricular nucleus of the hypothalamus (PVH) in GHSR-deficient mice, whereas the number of proopiomelanocortin (POMC) neurons and liraglutide-induced c-Fos activation—either in the entire arcuate nucleus or specifically within POMC neurons—remained unchanged compared to WT controls. Liraglutide-induced c-Fos expression in the lateral septum and PVH was reduced in GHSR-deficient mice. Conversely, pharmacological GHSR blockade using either JMV2959 or the endogenous antagonist/inverse agonist liver-expressed antimicrobial peptide 2 did not enhance liraglutide-induced food intake reduction. In conclusion, our findings reveal that genetic GHSR deficiency amplifies liraglutide's anorectic effects and provide new insight into the neurobiological mechanisms underlying this interaction. These results suggest that dual modulation of the GHSR and GLP-1R systems may represent a promising strategy for obesity treatment, though careful selection of GHSR-targeting agents and therapeutic protocols will be essential to optimize clinical outcomes.