RESUMEN
Background: The increasing incidence of obesity and its complications has become a global public health problem. Lingguizhugan decoction (LGZGD) is a representative compound of traditional Chinese medicine (TCM) for metabolic diseases, such as nonalcoholic fatty liver disease, but its role in insulin resistance (IR) treatment is still less known. This study aims to evaluate the therapeutic properties of LGZGD on obesity-induced IR and explore the potential mechanism of LGZGD on gut microbiota and its metabolites in the treatment of IR. Methods: In this study, we induced an IR model in the form of high-fat diet (HFD) rats gavaged with LGZGD (1.64 g/kg BW) for three weeks. The IR status was measured by biochemical assays and oral glucose tolerance tests. The degrees of damage to liver function and the intestinal barrier were observed by hematoxylin and eosin (H&E) staining and immunohistochemistry. Alterations in intestinal microbiota and metabolites were assessed by 16S rRNA and an untargeted metabolomics platform. Results: Our results showed that after LGZGD treatment, the body weight, plasma insulin concentration and blood lipids were significantly decreased, and glucose tolerance and hepatic steatosis were ameliorated. In addition, small intestinal villi were restored, and the expression of Occludin was upregulated. The relative abundance of Akkermansia, Faecalibacterium and Phascolarctobacterium in the HFD-LGZG group was upregulated. Obesity-related metabolic pathways, such as bile secretion, biosynthesis of amino acids, phenylalanine metabolism, serotonergic synapse, protein digestion and absorption, taurine and hypotaurine metabolism, and primary bile acid biosynthesis, were changed. After LGZGD intervention, metabolites developed toward the healthy control group. In addition, the expression of bile acid metabolism related genes was also regulated in IR rats. Conclusion: We showed that LGZGD relieved IR, possibly by regulating the composition of the fecal microbiota and its metabolites. The above studies provide a basis for further study of LGZGD in the treatment of IR and its clinical application.
RESUMEN
This study aimed to explore the effect of Linggui Zhugan Decoction(LGZGD)-containing serum on mitochondrial oxidative stress in cardiomyocytes based on the NF-E2-related factor2(Nrf2)/Bcl-2/adenovirus E1 B 19 kDa interacting protein(BNIP3) signaling pathway. After the preparation of LGZGD-containing serum and blank serum, H9 c2 cardiomyocytes were exposed to H_2O_2 for inducing oxidative stress in vitro. The H9 c2 cells were divided into four groups, namely normal control group, H_2O_2 model group, 20% blank serum group, and 20% LGZGD-containing serum group. After the cells were pre-treated with different types of serum for 12 h and cultured with 100 µmol·L~(-1 )H_2O_2 for 6 h, the reactive oxygen species(ROS) level in each group was detected by DCFH-DA, and the openness of mitochondrial permeability transition pore(mPTP) was measured using a calcein AM fluorescent probe. The expression levels of cytoplasmic cytochrome C(CytC), mitochondrial CytC, cytoplasmic and nuclear Nrf2, and BNIP3 were detected by Western blot. Nrf2-silenced H9 c2 cells were prepared by transfecting them with siRNA-Nrf2 for investigating the efficacy of LGZGD-containing serum in regulating ROS, mPTP, cytoplasmic and mitochondrial CytC, and BNIP3. The results showed that compared with the normal control group, H_2O_2 significantly increased the ROS content and mPTP openness(P<0.01), and the expression of Nrf2, BNIP3, and cytoplasmic CytC(P<0.01), and decreased the expression of mitochondrial CytC(P<0.01), without causing obvious change in cytoplasmic Nrf2. LGZGD-containing serum significantly lowered ROS content(P<0.01), inhibited mPTP openness(P<0.01), down-regulated the expression of cytoplasmic CytC and BNIP3(P<0.01), up-regulated mitochondrial CytC expression(P<0.01), and promoted Nrf2 nuclear translocation(P<0.05). However, after Nrf2 silencing, the reduced ROS production, diminished BNIP3 expression, and inhibited mPTP openness and CytC release induced by LGZGD-containing serum were reversed(P<0.01). These results have suggested that LGZGD-containing serum is able to alleviate the mitochondrial oxidative stress injury of cardiomyocytes by regulating the Nrf2/BNIP3 signaling pathway.