西洋参茎叶总皂苷对脂肪细胞糖脂代谢及胰岛素抵抗信号转导的影响

目的观察西洋参茎叶总皂苷(panax quinquefolius saponin,PQS)对脂肪细胞糖脂代谢及胰岛素抵抗信号转导的影响。方法将3T3-L1前脂肪细胞诱导分化为成熟脂肪细胞,用游离脂肪酸(FFA)制备脂肪细胞胰岛素抵抗(IR)模型,再加入相应药物作用,最后用葡萄糖氧化酶法检测药物作用后脂肪细胞培养液中葡萄糖消耗量,用比色法检测药物对肿瘤坏死因子-α(TNF-α)的脂解作用的影响,用Western-blot法检测胰岛素刺激后信号蛋白磷酸化水平。结果模型组葡萄糖消耗量(mmol/L)为5.250±2.671,显著低于对照组14.133±1.305(P0.01);与模型组相比,二甲双胍组(1 mmol/L及PQS大、中、小剂量组(0.08、0.04、0.02 mg/mL)葡萄糖消耗量均显著增加(P0.01),分别为11.807±1.358、10.784±2.373、10.217±1.237、9.984±2.006,且随着PQS用药剂量的增加,葡萄糖消耗量也逐渐增加。TNF-α组培养液中FFA浓度(nmol/μg)(2.479±0.597)显著高于对照组(1.320±0.538)(P0.01);与TNF-α组相比,二甲双胍及PQS大、中、小剂量组培养液中FFA浓度均显著降低(P0.01),分别为1.210±0.566、1.105±0.631、1.108±0.260、1.201±0.593,且随着PQS用药剂量的加大,其抗脂解作用逐渐增强。模型组胰岛素受体β亚单位、IRS-1酪氨酸磷酸化水平及PKB的Ser473磷酸化水平均较对照组减低;与模型组比较,PQS小剂量组信号蛋白磷酸化水平无明显变化,但PQS中、大剂量和二甲双胍组信号蛋白磷酸化水平均有不同程度增高的趋势。结论PQS能够促进脂肪细胞利用葡萄糖、抑制TNF-α的促脂解作用,从而调节糖脂代谢。PQS调节糖脂代谢的作用可能与其促进脂肪细胞胰岛素信号转导、改善胰岛素抵抗有关。

Effects of Panax Quinquefolius Saponin of Stem and Leaf on Glucose-Lipid Metabolism and Insulin Signal Transduction in Insulin Resistant Model Adipocytes

Objective To observe the effects of panax quinquefolius saponin （PQS） of stem and leaf on glucose-lipid metabolism and insulin signal transduction in the insulin resistant model of adipocytes. Methods The insulin resistant model of differentiated 3T3-L1 adipocytes was established in vitro with free fatty acid. After induction of insulin resistance, cells were treated with metformin or PQS for 2 days. The glucose consumption in culture fluid was detected by glucose oxidase method; the effects of PQS on the lipolysis induced by tumor necrosis factor （TNF-α） was observed using colorimetry; and the phospholation of signal proteins was detected by Western-blot. Results The amount of glucose consumption （mmol/L） in the model group （5. 250 ± 2. 671 ） was significantly lower than that in the normal control group （14. 133 ± 1. 305, P 〈 0. 01 ）, it increased in the meformin treated group （ 11. 807 ± 1. 358）, and the groups treated with high-, middle- and low-dose PQS dose-dependently （10. 784 ± 2. 373, 10.217 ± 1. 237 and 9. 984 ± 2. 006, respectively）, significantly higher than that in the model group （P 〈0.01 ）. Upon TNF-α treatment, the concentration of free fatty acid （FFA） （nmol/ μg） in culture medium was 2.479 ±0. 597, predominantly higher than that in the control group （1. 320 ±0.538, P〈0.01 ）, while it was 1. 210 ±0. 566 in the metformin group, 1. 105 ±0. 631 in high-dose PQS group, 1. 108 ± 0. 260 in the middle-dose PQS group, 1. 201 ±0. 593 in the low-dose PQS group, all were lower than that in theTNF-α group （P 〈0.05 or P 〈0.01 ）, and a dose-dependent tendency of PQS＇s action was seen. The tyrosine phosphorylation of insulin receptor and IRS-1 as well as Ser473 phosphorylation of PKB were lower in the model group than in the control group; they were insignificantly changed in the low-dose PQS group, but did show significant difference in comparing with those in the high-and middle-dose PQS groups or metformin group. Conclusien PQS can accelerate the glucose utilization and depress the lipolysis in adipocytes induced by TNF-α, which may be correlated with its promoting insulin signal transduction and improving insulin resistance in adipocytes.