Metformin mitigates metabolic dysfunction-associated steatohepatitis in rats by altering steatosis-related micro-RNAs and Aquaporin-9.

Metabolic dysfunction-associated steatohepatitis (MASH) represents a growing public health concern. While metformin is widely used in managing MASH, its effects on steatosis-related microRNAs (miRNAs) and hepatic Aquaporin 9 (AQP-9) expression remain unclear. This study aimed to evaluate the impact of a high-fat diet (HFD) and metformin treatment on body weight, hepatic steatosis, oxidative stress, miRNA expression, and AQP-9 levels in a rat model. Twenty-four male Sprague-Dawley rats were randomly divided into four groups. The control group received a baseline diet. The other three groups first received a 9-week high-fat diet (HFD) to induce MASH. The MASH group received no treatment, while the other two HFD groups were given oral metformin (100 or 200 mg/kg/day) for 8 weeks. Serum ALT, AST, inflammatory markers (TNF-α, IL-6) and lipid profile were measured. Hepatic levels of MDA, GSH, and nitric oxide were analyzed. miR-122, miR-33a, miR-34a, and miR-24 expressions were quantified using qRT-PCR. Liver underwent histopathological evaluation (H&E staining) and immunohistochemical analysis for AQP-9. Metformin boosted liver function and alleviated hepatic oxidative stress and inflammation by increasing GSH and suppressing inflammatory markers (TNF-α, IL-6), NO, and MDA levels. It also decreased the expression of steatosis-associated miRNAs (miR-122, miR-33a, miR-34a, and miR-24) and AQP-9. Histological findings showed reduced steatosis, inflammation, and hepatocyte ballooning, with better outcomes observed at the higher metformin dose. Metformin exerts a hepatoprotective effect in MASH, likely through modulation of inflammation, miRNA expression and suppression of AQP-9, leading to improved biochemical and histological liver profiles.