Rapamycin and Chloroquine Modulate Insulin Resistance and Hepatic Steatosis in a High-Fat/High-Cholesterol Diet-Induced Metabolic Dysfunction-Associated Steatotic Liver Disease Mouse Model.

Objective: To establish a short-term high-fat/high-cholesterol (HFHC) diet-induced Metabolic dysfunction-associated steatotic liver disease (MASLD) mouse model, and evaluate the effects of rapamycin (RaPa) and chloroquine (CQ) on this model to explore their therapeutic potential and side effects. Methods: An early MASLD mouse model was constructed via short-term HFHC diet feeding. Model mice were intraperitoneally injected with RaPa or CQ. Drug effects were analyzed on body weight, liver weight, lipid metabolism-related genes (APOB, FASN, PLIN2), inflammatory factors (IL-6, IL-10), and fibrosis markers (LOX, Col-1α-1, CCL2, TGFβ1, PDGFRβ, α-SMA) at mRNA and protein levels. Results: RaPa ameliorated body weight and liver weight in early MASLD mice, downregulated FASN and PLIN2 expression, upregulated IL-10 mRNA levels, and alleviated hepatic steatosis, but induced metabolic disorders such as Insulin resistance and hyperlipidemia. In contrast, CQ promoted FASN and PLIN2 expression, exacerbated hepatic steatosis, reduced IL-10 mRNA levels, and upregulated fibrosis-related markers (LOX, TGFβ1, PDGFRβ, α-SMA) at both mRNA and protein levels, thereby driving MASLD progression to liver fibrosis. Notably, CQ improved metabolic abnormalities in model mice, including obesity, hyperlipidemia, and Insulin resistance. Conclusion: RaPa and CQ exhibit dual effects on early MASLD: RaPa alleviates hepatic steatosis but exacerbates metabolic disorders, whereas CQ improves metabolic abnormalities but accelerates liver fibrosis. This paradox highlights the need to balance metabolic regulation and liver injury prevention in MASLD treatment, providing critical experimental insights for targeted drug development.