去卵巢2型糖尿病大鼠骨骼肌磷酯酰肌醇-3-激酶、丝氨酸／苏氨酸激酶2及核转录因子-kappa B的表达

Expression of pbosphatidylinositol-3-kinase , serine/ threonine-protein kinase 2 and nuclear transcription factor-kappa B in skeletal muscle of ovariectomized diabetic rats

目的探讨去卵巢2型糖尿病大鼠骨骼肌磷酯酰肌醇-3-激酶（PI3K）／丝氨酸／苏氨酸激酶2（Akt2）（PI3K／Akt2）信号通路相关因子及核转录因子-kappaB（NF—κB）表达的意义。方法29只雌性Wistar大鼠按随机数字表法分为对照组（NS，n=9），2型糖尿病组（DS，n=10），2型糖尿病去卵巢组（DOVX，n=10），体重180～200g。NS组大鼠正常饮食，DS和DOVX组大鼠给予高糖高脂饮食8周后，予腹腔注射链脲佐菌素30mg／kg，糖尿病成模后1周，DOVX组大鼠摘除双侧卵巢，NS和DS组大鼠仅切除少量脂肪。去卵巢前后各组大鼠分别称重及测定空腹血糖、空腹胰岛素，计算胰岛素敏感指数。去卵巢12周后各组大鼠取两侧股四头肌分别行免疫组化及逆转录-多聚酶链反应（RT—PCR）检测PI3K、Akt2和NF—κB的表达水平。多组间比较采用方差分析，以P〈0．05为差异有统计学意义。结果（1）DS组大鼠骨骼肌PI3KmRNA和Akt2mRNA分别为0．797±0．043和0．753±0．076，低于NS组（0．870±0．051和0．844±0．013，t=2．722、3．368，均P〈0．05），但高于DOVX组（0．715±0．068和0．666±0．038，t=2．686、2．526，均P〈0．05）。（2）DS组大鼠骨骼肌NF—κB mRNA为0．577±0．097，高于NS组（0．433±0．112，t=-3．147，P〈0．05），但低于DOVX组（0．696±0．090，t=-2．862，P〈0．05）。（3）各组大鼠骨骼肌均可见P13K、Akt2和NF—κB蛋白表达。DS组大鼠骨骼肌Pi3K和Akt2蛋白分别为（4．3±0．6）和（3．4±0．7），低于NS组（5．2±0．4、4．7±0．7，t=2．654、3．488，均P〈0．05），但高于DOVX组（3．5±0．6和2．8±0．5，t=3．473、2．365，均p〈0．05）。（4）DS组大鼠骨骼肌NF—κB蛋白表达为6．5±0．9，高于NS组大鼠（4．9±0．8，t=-3．396，P〈0．05），但低于DOVX组（8．1±0．8，t=-2．954，P〈0．05）。结论去卵巢2型糖尿病大鼠骨骼肌P13K和Akt2表达下降，NF—κB炎症因子激活可能导致胰岛素抵抗加重。

Objective To investigate the expression of phosphatidylinositol-3-kinase （PI3K）, serine/threonine-protein kinase 2 （Akt2） and nuclear transcription factor- κB （NF-κB） in skeletal muscle of ovariectomized diabetic rats. Methods Twenty-nine female Wistar rats were randomly divided into 3 groups： control group （NS group, n =9）, diabetic group （DS group, n = 10） and diabetic ovariectomized group （DOVX group, n = 10）. Rats in NS group were fed with a normal diet, while rats in DS and DOVX groups were fed with a high-carbohydrate/fat diet for 8 weeks and then were given an intraperitoneal injection of streptozotocin （ STZ, 30 mg/kg）. One week later, rats in DOVX group underwent ovariectomy, while rats in NS and DS groups were subjected to a sham operation, which was similar to ovariectomy except that only a small portion of abdominal fat was removed. Before and after ovariectomy, rats in each group were weighed, and fasting blood glucose, fasting plasma insulin were measured. At 12 weeks after the ovariectomy, the expression of PI3K, Akt2 and NF-κB in skeletal muscle of the rats was measured by immunohistochemistry and RT-PCR. Results （ 1 ） The mRNA levels of PI3K （0. 797 ± 0. 043 ） and Akt2 （0.753 ±0.076） in DS group were lower than the mRNA levels of PI3K （0. 870 ± 0.051 ） and Akt2 （0. 844 ± 0. 013） in NS group （ t = 2. 722, 3. 368, respectively, both P 〈 0. 05）, but higher than DOVX group （0. 715 ±0. 068, 0. 666 ±0. 038, and t = 2. 686, 2. 526, respectively, both P 〈0. 05）. （2） The mRNA level of NF-κB in rats of DS group （0. 577 -± 0. 097 ） was higher than that in NS group （0. 433 ± 0. 112, t= -3. 147, P〈0.05）, but less than that in DOVX group （0.696 ±0.090, t = -2.862, P〈 0. 05 ）. （ 3 ） The levels of PI3 K protein （4. 3 ± 0. 6） and Akt2 protein （ 3.4 ± 0. 7 ） in DS group were lower than the levels of PI3K protein （5.2 ±0. 4） and Akt2 protein （4. 7 ±0. 7） in NS rats （t = 2. 654, 3.488, respectively, both P 〈0. 05）, but lower than those in DOVX group （3.5 ± 0. 6, 2. 8 ± 0. 5, t = 3. 473, 2. 365, both P 〈0. 05）. （4） The level of NF-κB protein in DS group （6. 5 ±0. 9） was higher than that in NS group （4.9±0.8, t = -3.396, P 〈0.05）, but lower than that in DOVX group （8. 1±0.8, t = -2. 954, P 〈 0. 05 ）. Conclusion The expression of PI3K and Akt2 is decreased and the expression of NF-κB is increased in skeletal muscle of ovariectomized diabetic rats, which might lead to insulin resistance.