The Preventive Effect of Total Saponins from Panax japonicas on Inflammation and Insulin Resistance in Adipose Tissue of Mice Induced by High-Fat Diet

Background: In the present research, we aimed to investigate the effects of total saponins from Panax japonica (TSPJ) on adipocyte inflammation and insulin resistance induced by a high-fat diet (HFD). Moreover, its underlying mechanism was also further explored. Methods: C57/BL mice were randomly divided into four groups as follows: normal diet (ND) group, HFD group, and two TSPJ + HFD groups (30 mg/kg and 90 mg/kg). Insulin resistance test, glucose tolerance test, fat index analysis, histopathological assay, Western blotting analysis, and real-time PCR were performed to analyze the protective effect of TSPJ on adipose tissue. The protective mechanism of TSPJ on 3T3-L1 cells was studied in vitro by Oil Red O staining, 2-deoxyglucose uptake measurement etc. . Findings: In vivo, we found that TSPJ inhibited the activation of NF-κB and increase the transcription of p-AKT, leading to reduced inflammation and improved the sensitivity of adipocytes to insulin. In vitro evaluation revealed that palmitic acid (PA) induced inflammation by activating the NF-κB pathway, and induced insulin resistance by affecting the expressions of p-AKT in adipocytes. TSPJ pre-treatment could prevent such these response in a dose-dependent manner. TSPJ might exert its protective effect on 3T3-L1 cells by affecting the expression of AMPK. Interpretations: Our study showed that TSPJ could inhibit adipocyte inflammation by inhibiting NF-κB pathways. In addition, TSPJ could also affect the expressions of p-AKT to increase insulin sensitivity in adipocytes via targeting AMPK. Funding: This study was financially supported by the grants from National Natural Science Foundation of China. Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: This study was financially supported by the grants from National Natural Science Foundation of China (Grant No. 81773959 to C.F. Yuan and No. 81974528 to C.F. Yuan) and Health commission of Hubei Province scientific research project in China. (Grant No. WJ2019H527 to C.F. Yuan).