Potential Synergistic Effects of Caffeine and Naringin on Mitochondrial Biogenesis and Hepatic Steatosis in Adult Male Rats With NAFLD Induced by a High-Fat Diet.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide, and disturbances in lipid metabolism and mitochondrial function play a significant role in its progression. In this study, to improve the effects of caffeine (CAF) treatment, we evaluated the effects of CAF and naringin (NAR) alone and in combination on gene expression involved in mitochondrial biogenesis, plasma nonesterified fatty acid (NEFA) levels, hepatic TG levels, and pathological changes in the liver tissue in adult male rats with NAFLD induced by a high-fat diet (HFD). Then, 35 male Wistar rats were randomly assigned to five groups: control, HFD, HFD + CAF, HFD + NAR, and HFD + CAF + NAR (seven rats per group). They were fed a HFD containing 51% fat for 10 weeks, followed by a 6-week gavage treatment with CAF (50 mg/kg/day) and NAR (12.5 mg/kg/day), either individually or in combination. Gene expression related to mitochondrial biogenesis (SIRT1, PGC1, and TFAM), serum NEFA levels, hepatic triglyceride (TG) levels, and liver histological changes were assessed. The combination of CAF and NAR in the HFD + CAF + NAR group significantly increased the expression of SIRT1 ( < 0.01), PGC1- ( < 0.01), and TFAM ( < 0.05) compared to the HFD group, while single treatments did not show such effects. Serum NEFA levels did not change significantly in any of the groups (HFD and treatment groups), but liver TG levels were significantly reduced in both single and combination treatments ( < 0.001). Pathological changes, including improvements in steatosis, inflammation, and ballooning, were observed in the treatment groups, particularly in the HFD + CAF + NAR group. Based on current findings, the combined use of CAF and NAR as an adjunct therapy may exert its protective effects by enhancing the expression of genes involved in mitochondrial biogenesis, improving liver lipid levels, and ameliorating liver pathology. Therefore, it can be considered an innovative strategy for improving liver metabolic status in the context of NAFLD.