Metabolic-associated fatty liver disease (MAFLD) is a clinical syndrome characterized by hepatocellular steatosis and excessive fat deposition caused by unclear liver-damaging factors [1]. This disease is significantly associated with metabolic and cardiovascular diseases such as type 2 diabetes and atherosclerosis and can directly lead to cirrhosis and liver cancer [2], [3]. In recent years, the incidence of MAFLD has been increasing annually, with a global prevalence of up to 25.54 %, making it the most common type of liver disease worldwide and a serious threat to human health [4], [5], [6], [7]. Many factors affect MAFLD, and its pathogenesis is not yet fully understood. However, multiple studies have shown that gut microbiota dysbiosis is significantly related to the occurrence and development of MAFLD [1], [8], [9], [10]. MAFLD results from lipotoxicity caused by the accumulation of toxic lipid substances, pro-inflammatory cell infiltration leading to hepatocyte damage, and hepatic stellate cell fibrosis, which secretes excessive extracellular matrix, impairing the structure and function of the liver [11], [12]. Recent studies have shown that improving intestinal microorganisms can prevent and treat MAFLD. Intestinal microbial disorders and bile acid metabolism disorders change an individual's susceptibility to MAFLD. Currently, the number of MAFLD patients is gradually increasing, showing a trend toward younger age, with many complications that seriously endanger human health [13]. There is still no effective Western medicine for the treatment of MAFLD, but the advantages of Chinese medicine have gradually become apparent. The use of multiple therapies in Chinese medicine and the combination of Chinese and Western medicine in treating MAFLD are more effective, reflecting a comprehensive treatment approach [14], [15].

Jiawei Xiaoyao San is derived from Xiaoyao San and originates from the "Taiping Huimin Hejiju Fang." It has the effects of soothing the liver, clearing heat, strengthening the spleen, and nourishing the blood. It is often used to treat liver stagnation and blood deficiency conditions [16]. As a classic Chinese medicine formula, Jiawei Xiaoyao San has the effects of soothing the liver and relieving depression, strengthening the spleen and stomach, and regulating blood [17]. Traditional Chinese Medicine (TCM) as a conventional treatment method has unique advantages in treating gastrointestinal diseases. Jiawei Xiaoyao San is an effective compound prescription in TCM for regulating emotions and alleviating psychological stress. It comprises various Chinese herbs, including Bupleurum, Atractylodes macrocephala, Poria, White Peony Root, Fresh Ginger, Chinese Yam, Tribulus terrestris, and Dictamnus, which has the effects of soothing the liver and strengthening the spleen, nourishing blood, and moistening dryness. Although the exact pathogenesis of MAFLD is not fully understood, a large number of studies have shown that gut flora and bile acid metabolism are closely related to MAFLD. The interaction between these two factors may accelerate the progression of the disease. Therefore, this study aims to explore the improvement effect of Jiawei Xiaoyaosan on the rat MAFLD model, focusing on gut flora and bile acid metabolism.

In this study, a rat model of MAFLD was established to investigate the therapeutic mechanisms of Jiawei Xiaoyao San (JWXYS) in treating liver stagnation and spleen deficiency-type liver disease. The ameliorative effects of JWXYS on MAFLD were first evaluated by assessing key biochemical markers, including AST, ALT, TC, and TG, as well as by histological analyses such as Oil Red O and HE staining. Furthermore, the underlying mechanisms were elucidated through Quantitative real-time PCR (RT-qPCR), Western blot (WB), gut microbiota metabolism, and bile acid metabolism, thereby providing experimental evidence to support the potential clinical application of JWXYS in the treatment of MAFLD.