Soshiho-Tang Aqueous Extract Exerts Antiobesity Effects in High Fat Diet-Fed Mice and Inhibits Adipogenesis in 3T3-L1 Adipocytes

Abstract

Soshiho-tang (SST; sho-saiko-to in Japanese; xiaochaihu-tang in Chinese) has generally been used to improve liver fibrosis- and cirrhosis-related symptoms in traditional Korean medicine. Although many studies have investigated the pharmacological properties of SST, its antiobesity effect has not been elucidated. Thus, our present study was carried out to evaluate the antiobesity effect of SST using a high fat diet- (HFD) induced obese mouse model and 3T3-L1 adipose cells. C57BL/6J mice were randomly divided into four groups (n = 6/group), normal diet (ND), HFD-fed group, and HFD- and SST-fed groups (S200: 200 mg/kg of SST; S600: 600 mg/kg of SST) and given HFD with or without SST extract for 8 weeks. 3T3-L1 preadipocytes were differentiated into adipocytes for 8 days with or without SST. In the HFD-fed obese mice, body weight and fat accumulation in adipose tissue were significantly reduced by SST administration. Compared with control-differentiated adipocytes, SST significantly inhibited lipid accumulation by decreasing the triglyceride (TG) content and leptin concentration in 3T3-L1 adipocytes. SST also decreased the expression of adipogenesis-related genes including lipoprotein lipase (LPL), fatty acid binding protein 4 (FABP4), CCAAT/enhancer-binding protein-alpha (C/EBP-α), and peroxisome proliferator-activated receptor-gamma (PPAR-γ). Our findings suggest that SST has potential as a nontoxic antiobesity medication.

Figure 1

Effects of SST extract on (a) body weight change, (b) final body weight, and (c) adipose tissue weight. Values with the different superscript letters indicate statistical significance (p < 0.05) between groups by Duncan's multiple range test. ND: normal diet-fed group, HFD: high fat diet-fed group, S200: HFD-fed group with 200 mg/kg of SST, and S600: HFD-fed group with 600 mg/kg of SST.

Figure 2

Effects of SST on plasma levels of (a) TG, (b) total cholesterol, and (c) leptin production in HFD-fed mice. Values with the different superscript letters indicate statistical significance (p < 0.05) between groups by Duncan's multiple range test. ND: normal diet-fed group, HFD: high fat diet-fed group, S200: HFD-fed group with 200 mg/kg of SST, and S600: HFD-fed group with 600 mg/kg of SST.

Figure 3

Cytotoxic effects of SST in (a) preadipocytes and (b) adipocytes. (a) 3T3-L1 preadipocytes were treated with various concentrations of SST for 24 h. (b) 3T3-L1 preadipocytes were differentiated into adipocytes by incubation with isobutylmethylxanthine, dexamethasone, and insulin (MDI) for 8 days. The cells were exposed to various concentrations of SST during the differentiation period. Data are presented as mean ± SEM.

Figure 4

Inhibitory effect of SST extract on TG production in 3T3-L1 adipocytes. 3T3-L1 preadipocytes were differentiated into adipocytes by incubation with isobutylmethylxanthine, dexamethasone, and insulin (MDI) for 8 days. The cells were treated with or without SST or GW9662 (20 μM) during the differentiation period. (a) Lipid accumulation in the cells was analyzed by Oil-Red O staining. (b) The TG content was measured enzymatically using a commercial kit. (c) Culture supernatant was collected from the SST-treated cells. Leptin production was determined by ELISA by using a mouse leptin immunoassay kit. Data are presented as mean ± SEM. ^∗ p < 0.05 and ^∗∗∗ p < 0.001 versus differentiated cells. GW9662 (20 μM) was used as a positive control.

Figure 5

Effects of SST on protein expression of lipid metabolism-related genes in 3T3-L1 adipocytes. 3T3-L1 adipocytes were exposed to various concentrations of SST or GW9662 (20 μM) during the differentiation period. Cell lysates were prepared and subjected to Western blotting for PPAR-γ and C/EBP-α (a) and FAS, perilipin, and FABP4 (b). β-Actin was used as a loading control.

Figure 6

Effects of SST on mRNA expression of lipid metabolism-related genes in 3T3-L1 adipocytes. 3T3-L1 adipocytes were exposed to various concentrations of SST or GW9662 (20 μM) during the differentiation period. Total RNA was isolated and subjected to RT-PCR for FASN, FABP4, LPL, C/EBP-α, and PPAR-γ. β-Actin was used as a housekeeping gene.