目的 研究龙胆苦苷对2型糖尿病（T2DM）小鼠骨骼肌胰岛素抵抗的作用并探讨其作用机制。方法C57BL/6J小鼠高脂饮食饲养10周后，ip链脲佐菌素（STZ）诱导形成T2DM模型，将模型成功小鼠随机分为模型组和龙胆苦苷低、高剂量（25、50 mg·kg⁻¹）组，普通饲料喂养组小鼠作为对照组，ig给药8周，对照组和模型组ig给予相应体积的0.5%的羧甲基纤维素钠。每周测定小鼠的体质量、餐后随机血糖（PBG）和空腹血糖（FBG）；开展口服葡萄糖耐量、胰岛素耐量实验；处死小鼠前1周尾尖采血测定糖化血红蛋白（HbA1c）水平；处死小鼠后试剂盒法测定血清中脂质含量；病理染色观察龙胆苦苷对糖尿病小鼠骨骼肌形态的影响；试剂盒法测定血清和骨骼肌中氧化应激相关指标；免疫荧光法检测小鼠胰腺中胰岛素和胰高血糖素水平；Western blotting法测定骨骼肌中磷酸肌醇3-激酶（PI3K）/蛋白激酶B（Akt）信号通路，核因子E2相关因子2（Nrf2）信号通路和胰岛素抵抗信号通路相关蛋白的水平。结果 与模型组相比，龙胆苦苷降低T2DM小鼠的血糖和HbA1c水平（P＜0.05、0.01）；明显改善T2DM小鼠的口服葡萄糖耐量异常（P＜0.05、0.01），提高T2DM小鼠对胰岛素的敏感性（P＜0.05、0.01）；显著增加T2DM小鼠胰腺中胰岛素含量（P＜0.05、0.01），降低胰高血糖素含量（P＜0.05、0.01），改善骨骼肌形态异常；此外，龙胆苦苷改善T2DM小鼠血脂紊乱，增强血清和骨骼肌中抗氧化酶活性和增加抗氧化物质水平（P＜0.05、0.01），降低丙二醛（MDA）含量（P＜0.05）；蛋白检测结果表明龙胆苦苷上调骨骼肌中磷酸化蛋白PI3K、Akt、胰岛素受体底物-1（IRS1）表达（P＜0.05、0.01），增加骨骼肌中蛋白葡萄糖转运蛋白-4（GLUT4）、Nrf2、NADPH醌氧化还原酶-1（NQO1）、血红素加氧酶-1（HO-1）和谷氨酰半胱氨酸连接酶催化亚单位（GCLC）表达（P＜0.05、0.01），抑制骨骼肌蛋白KELCH样ECH关联蛋白1（Keap1）表达（P＜0.05、0.01）。结论 龙胆苦苷可能通过调控PI3K/Akt信号通路减轻骨骼肌氧化损伤和改善骨骼肌胰岛素抵抗，进而发挥其治疗T2DM作用。

Objective To study the effect of gentiopicrosid (GPS) on insulin resistance in skeletal muscle of the type 2 diabetes mellitus (T2DM) mice and explore its mechanism. Methods After C57BL/6J mice were fed with high-fat diet for 10 weeks, the T2DM model was induced by intraperitoneal injection of streptozotocin (STZ). The successful model mice were randomly divided into model group, GPS low and high dose (25 and 50 mg·kg⁻¹) groups, and the mice in the normal diet group were administered ig for eight weeks. The control group and model group were ig given 0.5% sodium carboxymethyl cellulose. Body mass, postprandial random blood glucose (PBG) and fasting blood glucose (FBG) were measured weekly. Oral glucose tolerance and insulin tolerance tests were carried out. Hemoglobin a1c (HbA1c) was measured by blood sampling at tail tip 1 week before the mice were killed. The serum lipid content was determined by kit method after killing mice. The effect of GPS on skeletal muscle morphology in diabetic mice were observed by pathological staining. The oxidative stress related indexes in serum and skeletal muscle of diabetic mice were determined by biochemical method. The levels of the insulin and pancreatic hyperglycemia in pancreas of the mice were measured by immunofluorescence. The expressions of the phosphoinositide 3- kinase (PI3K)/protein kinase B (Akt) signal pathway, nuclear factor E2 associated factor 2 (Nrf2) signal pathway and insulin resistance signal pathway in skeletal muscle were evaluated by Western blotting. Results Compared with the model group, GPS reduced the levels of blood glucose and glycosylated hemoglobin in T2DM mice (P < 0.05 and 0.01). GPS obviously attenuated the abnormal oral glucose tolerance and insulin sensitivity of the T2DM mice (P < 0.05 and 0.01). GPS discernibly increased the content of insulin (P < 0.05 and 0.01), decreased the content of glucagon in pancreas (P < 0.05 and 0.01), and ameliorated the morphological abnormalities of skeletal muscle in T2DM mice. Additionally, GPS alleviated the dyslipidemia, enhanced the activity of antioxidant enzymes and increased the levels of antioxidant substances (P < 0.05 and 0.01), and reduced the content of malondialdehyde (MDA) in serum and skeletal muscle of the T2DM mice (P < 0.05). The results of protein detection showed that GPS upregulated the expression of phosphorylated proteins PI3K, AKT and insulin receptor substrate-1 (IRS1) in skeletal muscle (P < 0.05 and 0.01). GPS increased the expression of protein glucose transporters type 4 (GLUT4), Nrf2, NADPH quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC) in skeletal muscle (P < 0.05 and 0.01), and inhibited the expression of protein KELCH like epichlorohydrin associated protein-1 (Keap1) (P < 0.05 and 0.01). Conclusion GPS may reduce oxidative damage and improve insulin resistance of skeletal muscle by regulating PI3K/Akt signaling pathway, and then play its anti-T2DM role.

R285.5

四川省自然科学基金青年基金项目（2023NSFSC1676）；南充市市校科技战略合作项目（22SXZRKX0012）；南充市科技计划项目（23YYJCYJ0026）；川北医学院校级杰出青年项目（CBY23-JQ03）；川北医学院附属医院科研发展计划项目（2023PTZK022）；四川省大学生创新创业项目（S202310634043, S202310634066）；上海市科委启明星（扬帆专项）项目（22YF1439800）