To study the mechanism of mangiferin alleviating liver injury induced by high-fat and high-sugar diet in obese rats based on oxidative stress signaling pathway.

Forty SD rats were divided into blank control group (NC) (raised normally and given the same amount of normal saline), model group (fed with high-fat and high-sugar diet and given the same amount of normal saline), the mangiferin administration group (MGF) (fed with high-fat and high-sugar diet), and mangiferin administration+miR-195-3p mimics group (MGF+miR-195-3p mimics) (fed with high-fat and high-sugar diet and administered 40 mg·kg^-1 mangiferin suspension, in addition, recombinant lentiviruses containing miR-195-3p mimics were injected into the tail vein), with 10 rats in each group. After treatment, body mass, visceral fat mass and liver coefficient were measured, blood glucose, blood lipid, aminotransferase, liver glycogen and oxidative stress related factors were detected by kit, and histopathological status of liver was detected by hematoxylin-eosin (HE) staining. Real-time quantitative fluorescence polymerase chain reaction (qRT-PCR) and fluorescence in situ hybridization (FISH) were used to detect the levels of miR-195-3p, and protein Western blot (WB) was used to detect the expression levels of nuclear factor erythroidderived 2-like 2 (Nrf2) and heme oxygenase-1 (HO-1).

After different treatment, the liver coefficients of NC group, Model group and MGF group were (2.20±0.29)%, (3.11±0.40)% and (2.75±0.32)%, respectively. Insulin was (310.63±38.06), (426.59±55.35) and (378.57±42.81) ng·L^-1; glutamic pyruvic transaminase was (55.17±6.11), (137.57±17.45) and (106.85±12.66) U·L^-1, respectively. The liver glycogen was (21.64±2.98), (7.96±1.03) and (15.52±2.16) mg·g^-1, respectively. The malondialdehyde levels in Model group, MGF group and MGF+miR-195-3p mimics group were (9.63±1.22), (7.79±0.91) and (9.11±1.16) mmol·g^-1, respectively, super oxide dismutase was (110.42±14.57), (251.36±36.26) and (181.45±20.95) U·g^-1, and Nrf2 mRNA was 1.00±0.12, 1.97±0.20, 1.29±0.15, respectively. The mRNA of HO-1 was 1.00±0.14, 2.84±0.35 and 1.81±0.29, respectively. Comparison of Model group with NC group, MGF group with Model group and MGF+miR-195-3p mimics group with MGF group showed statistically significant differences in the above indexes (all P<0.05).

Mangiferin can reduce liver injury and regulate glucose and lipid metabolism in obese rats, and its mechanism may be related to the down-regulation of miR-195-3p expression and activation of Nrf2/HO-1 signaling pathway.