GPR30 selective agonist G-1 induced insulin resistance in ovariectomized mice on high fat diet and its mechanism

Background: Previous in vivo and in vitro studies have demonstrated that Estrogen receptor Agonist G-1 regulates glucose and lipid metabolism. This study focused on the effects of G-1 on cardiometabolic syndrome and anti-obesity under a high fat diet (HFD).

Methods: Bilateral ovariectomized female mice were fed an HFD for 6 weeks, and treated them with G-1. A cardiomyocyte Insulin resistance model was used to simulate the in vivo environment. The main outcome measures were blood glucose, body weight, and serum Insulin levels to assess Insulin resistance, while cardiac function and degree of fibrosis were assessed by cardiac ultrasound and pathological observations. We also examined the expression of p-AMPK, p-AKT, and GLUT4 in mice hearts and in vitro models to explore the mechanism by which G-1 regulates Insulin signaling.

Results: G-1 reduced body weight in mice on an HFD, but simultaneously increased blood glucose and promoted Insulin resistance, resulting in myocardial damage. This damage included disordered cardiomyocytes, massive accumulation of glycogen, extensive fibrosis of the heart, and thickening of the front and rear walls of the left ventricle. At the molecular level, G-1 enhances gluconeogenesis and promotes glucose production by increasing the activity of pyruvate carboxylase (PC) while inhibiting GLUT4 translocation via the AMPK/TBC1D1 pathway, thereby limiting glucose uptake.

Conclusion: Despite G-1's the potential efficacy in weight reduction, the concomitant induction of Insulin resistance and cardiac impairment in conjunction with an HFD raises significant concerns. Therefore, comprehensive studies of its safety profile and effects under specific conditions are essential prior to clinical use.

AMPK; Cardiac metabolic syndrome; GPR30; Insulin resistance; Menopause.