目的 研究龍膽苦苷對2型糖尿?。═2DM）小鼠骨骼肌胰島素抵抗的作用并探討其作用機制。方法C57BL/6J小鼠高脂飲食飼養(yǎng)10周后，ip鏈脲佐菌素（STZ）誘導形成T2DM模型，將模型成功小鼠隨機分為模型組和龍膽苦苷低、高劑量（25、50 mg·kg⁻¹）組，普通飼料喂養(yǎng)組小鼠作為對照組，ig給藥8周，對照組和模型組ig給予相應體積的0.5%的羧甲基纖維素鈉。每周測定小鼠的體質量、餐后隨機血糖（PBG）和空腹血糖（FBG）；開展口服葡萄糖耐量、胰島素耐量實驗；處死小鼠前1周尾尖采血測定糖化血紅蛋白（HbA1c）水平；處死小鼠后試劑盒法測定血清中脂質含量；病理染色觀察龍膽苦苷對糖尿病小鼠骨骼肌形態(tài)的影響；試劑盒法測定血清和骨骼肌中氧化應激相關指標；免疫熒光法檢測小鼠胰腺中胰島素和胰高血糖素水平；Western blotting法測定骨骼肌中磷酸肌醇3-激酶（PI3K）/蛋白激酶B（Akt）信號通路，核因子E2相關因子2（Nrf2）信號通路和胰島素抵抗信號通路相關蛋白的水平。結果 與模型組相比，龍膽苦苷降低T2DM小鼠的血糖和HbA1c水平（P＜0.05、0.01）；明顯改善T2DM小鼠的口服葡萄糖耐量異常（P＜0.05、0.01），提高T2DM小鼠對胰島素的敏感性（P＜0.05、0.01）；顯著增加T2DM小鼠胰腺中胰島素含量（P＜0.05、0.01），降低胰高血糖素含量（P＜0.05、0.01），改善骨骼肌形態(tài)異常；此外，龍膽苦苷改善T2DM小鼠血脂紊亂，增強血清和骨骼肌中抗氧化酶活性和增加抗氧化物質水平（P＜0.05、0.01），降低丙二醛（MDA）含量（P＜0.05）；蛋白檢測結果表明龍膽苦苷上調骨骼肌中磷酸化蛋白PI3K、Akt、胰島素受體底物-1（IRS1）表達（P＜0.05、0.01），增加骨骼肌中蛋白葡萄糖轉運蛋白-4（GLUT4）、Nrf2、NADPH醌氧化還原酶-1（NQO1）、血紅素加氧酶-1（HO-1）和谷氨酰半胱氨酸連接酶催化亞單位（GCLC）表達（P＜0.05、0.01），抑制骨骼肌蛋白KELCH樣ECH關聯蛋白1（Keap1）表達（P＜0.05、0.01）。結論 龍膽苦苷可能通過調控PI3K/Akt信號通路減輕骨骼肌氧化損傷和改善骨骼肌胰島素抵抗，進而發(fā)揮其治療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

四川省自然科學基金青年基金項目（2023NSFSC1676）；南充市市?？萍紤?zhàn)略合作項目（22SXZRKX0012）；南充市科技計劃項目（23YYJCYJ0026）；川北醫(yī)學院校級杰出青年項目（CBY23-JQ03）；川北醫(yī)學院附屬醫(yī)院科研發(fā)展計劃項目（2023PTZK022）；四川省大學生創(chuàng)新創(chuàng)業(yè)項目（S202310634043, S202310634066）；上海市科委啟明星（揚帆專項）項目（22YF1439800）