糖胰敏对2型糖尿病糖脂代谢紊乱的改善作用及机制研究

目的探讨糖胰敏对2型糖尿病(T2DM)模型大鼠糖脂代谢紊乱的改善作用及相关机制。方法采用高糖高脂饲料喂养联合低剂量链脲佐菌素(STZ)腹腔注射建立2型糖尿病大鼠模型。将90只Wistar大鼠分为正常对照组、模型对照组、达美康组及糖胰敏高、中、低剂量组。治疗前后动态监测各组大鼠空腹血糖(FBG),血脂包括三酰甘油(TC)、总胆固醇(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)、空腹血清胰岛素(FINS)。计算胰岛素抵抗指数(IRI)、胰岛素敏感指数(ISI)、胰岛素分泌指数(IS)。结果与正常对照组比较,模型对照组大鼠FBG、FINS、TG、TC、LDL、IRI水平均明显升高(P均<0.05),ISI、IS、HDL水平均明显降低(P均<0.05)。糖胰敏治疗2周后大鼠血糖开始下降,治疗4周后,糖胰敏中、高剂量组以及达美康组大鼠FBG、TC、TG、LDL-C、IRI水平均明显降低(P均<0.05),而HDL-C、ISI和IS水平均明显升高(P均<0.05)。结论糖胰敏可通过调节糖脂代谢,降低脂毒性,增强胰岛组织对胰岛素的敏感性,从而有效发挥其改善糖脂代谢紊乱和降脂降糖的作用。

糖胰敏对实验性胰岛素抵抗糖尿病大鼠脂毒性和胰岛素抵抗的影响

目的:探讨糖胰敏对实验性胰岛素抵抗糖尿病模型大鼠脂毒性和胰岛素抵抗的改善作用,明确糖胰敏治疗2型糖尿病(T2DM)的机理。方法:采用高糖高脂饲料喂养联合低剂量链脲佐菌素(STZ)腹腔注射建立实验性胰岛素抵抗(IR)糖尿病大鼠模型。实验分为正常对照组、模型对照组、达美康对照组、糖胰敏高、中、低剂量组。治疗前及治疗1周后开始动态监测各组大鼠体质量及空腹血糖(FBG)。治疗4周后,血糖仪检测空腹血糖,全自动生化仪检测血脂,放射免疫检测法测定血清胰岛素(FINS)。计算体重指数(BMI)、胰岛素抵抗指数(IRI)、胰岛素敏感指数(ISI)、胰岛素分泌指数(IS),HE染色观察胰腺组织病理形态学变化。结果:T2DM模型组大鼠体质量和BMI较正常对照组显著增高(P<0.01,P<0.05);治疗4周后,糖胰敏中、高剂量组及达美康组大鼠体质量和BMI较治疗前明显下降(P<0.05)。与正常对照组比较,模型组大鼠血糖、血清FINS、TG、TC、LDL,IRI明显升高(P<0.05),ISI、IS、HDL明显降低(P<0.05);糖胰敏治疗2周后大鼠血糖开始下降,治疗4周后,糖胰敏中、高剂量组以及达美康组大鼠空腹血糖、TC、TG、LDL-C、IRI均明显降低(P<0.05),而HDL-C、ISI和IS明显升高(P<0.05);胰腺组织病理形态学观察结果显示糖胰敏组胰腺形态结构较模型组清晰完整,胰岛数量及胰岛内细胞数量较模型组明显增多,胰岛形态结构明显较模型组清晰完整,且糖胰敏高剂量组对胰岛病理形态学的改善作用最显著。结论:中药复方糖胰敏可通过调节糖脂代谢,降低脂毒性,改善胰岛β细胞功能,增强组织对胰岛素的敏感性,从而有效降低实验性胰岛素抵抗糖尿病大鼠的血糖。

糖胰敏对2型糖尿病大鼠胰岛β细胞凋亡的影响

目的:探讨糖胰敏对实验性2型糖尿病(T2DM)模型大鼠胰岛β细胞凋亡的影响,阐明糖胰敏治疗T2DM的药效机理。方法:采用小剂量STZ腹腔注射联合高热量饲料喂养建立T2DM大鼠模型;实验设正常对照组、T2DM模型组、糖胰敏大、中、小剂量组、西药达美康对照组;治疗前及治疗1周后,开始定期动态地监测血糖变化,治疗4周后检测血糖、血脂、血清胰岛素、计算胰岛素敏感指数(ISI),进行胰岛免疫组织化学分析,观察胰腺组织病理形态学变化和胰岛β细胞凋亡情况。结果:治疗2周后大鼠血糖开始下降,与模型组比较,糖胰敏大剂量组大鼠血糖明显降低;治疗4周后,与模型组比较,糖胰敏组大鼠血糖、血甘油三酯(TC)、血总胆固醇(TG)、游离脂肪酸(FFA)均明显降低,胰岛素敏感指数明显升高;胰岛病理学观察结果显示糖胰敏治疗组胰岛数量及胰岛内细胞数量较模型组明显增多,胰岛素阳性表达显著增强。胰岛细胞凋亡明显减弱。结论:中药复方糖胰敏能够有效降低T2DM模型大鼠的血糖、改善脂代谢紊乱,提高胰岛素敏感性,其机理可能为调节糖脂代谢,降低糖毒性、脂毒性,减少胰岛细胞凋亡,改善胰岛β细胞功能,从而有效发挥降低血糖的作用。

EFFECT OF CHRONIC ACE INHIBITIONONGLUCOSE TOLERANCE AND INSULIN SENSITIVITY IN HYPERTENSIVE TYPE 2 DIABETIC PATIENTS

We studied 14 moderately overweight Typo 2 diabetic patients with essential hypertension in stable metabolic control after a run-in period , and again after 3 months of antihypertensive treatment with the angiotensin-converting enzyme (ACF) inhibitor captopril. Glucose tolerance was tested with a 75g oral glucose load (OGTT) and insulin sensitivity was measured by the insulin suppression test (IST) while dietary and drug treatment of the hyperglycemia was maintained constant. In the whole group. mean blood pressure (MBP) fell progressively over 3months from a baseline value of 123± 3 mmHg (1 mmHg= 0. 133 kpa) to a final value of 115± 2 mmHg(P<0. 005). After treatment, fasting plasma glucose, insulin, free fatty acid (FFA). potassium, and glycosylated hemoglobin concentrations were unchanged from baseline. There were no significant differences in glucose tolerance and insulin sensitivity between pre- and post-trearment values. Neither endogenous (oral glucose) nor exogenous (IST) insulin caused any change in plasma potassium concentration. This resistance to the hypokalemic action of insulin was not affected by captopril.

Antihyperglycemic, insulinsensitizing and antioxidant activities of the active fractions from Anoectochilus chapaensis

Anoectochilus chapaensis Gagnep. （Orchidaceae）, an indigenous and valuable Chinese folk medicine, has been widely used in China to treat diabetes. However, few reports are available about its constituents and activity. The present experiment was conducted to investigate the active fractions from A. chapaensis in diabetic rat model induced by high-fat diet plus streptozotocin. The total EtOH extract from the whole herbs ofA. chapaensis, half of which was partitioned in sequence with petrol ether （PE）, ethyl acetate （EtOAc）, n-BuOH and H2O, thus yielding four fractions, all of them were orally administered with an identical dose amount to 4 g/kg dried crude herbs once a day for consecutive two weeks to further investigate the antihyperglycemic activity. The EtOAc fraction caused a significant fall in the non-fasting blood glucose level of diabetic rats from （402.66±82.26） to （226.26±62.10） mg/dl, which may be attributed to ameliorating insulin resistance, modulating the activity of enzymatic antioxidants, reducing the content of NO, etc. Much more intact β cells in the islets of Langerhans in EtOAc fraction-treated groups than the negative control were observed, which greatly supported the morphological and functional elucidation. The OGTT evidenced that EtOAc fraction could promote the endurance capacity of acute glucose increase in diabetic rats. The EtOAc fraction of A. chapaensis contains some hypoglycemic and antioxidant principles with the potential to be developed further for the treatment of diabetes specifically associated with an insulin resistance state.

A correlation study of the expression of resistin and glycometabolism in muscle tissue after traumatic brain injury in rats

Objective： To investigate the expression pattern of resistin （RSTN） in skeletal muscle tissue and its influence on glycometabolism in rats with traumatic brain injury （TBI）. Methods： Seventy-eight SD rats were randomly divided into traumatic group （n=36）, RSTN group （n=36） and sham operation group （n=6）. Fluid percussion TBI model was developed in traumatic and RSTN groups and the latter received additional 1 mg RSTN antibody treatment for each rat. At respectively 12 h, 24 h, 72 h, 1 w, 2 w, and 4 w after operation, venous blood was collected and the right hind leg skeletal muscle tissue was sampled. We used real-time PCR to determine mRNA expression of RSTN in skeletal muscles, western blot to determine RSTN protein expression and ELISA to assess serum insulin as well as fasting blood glucose （FBG） levels. Calculation of the quantitative insulin sensitivity check index （Q value） was also conducted. The above mentioned indicators and their correction were statistically analyzed. Results： Compared with sham operation group, the RSTN expression in the skeletal muscle as well as serum insulin and FBG levels revealed significant elevation （P〈0.05）, and reduced Q value （P〈0.05） in traumatic group. Single factor linear correlation analysis showed a significant negative correlation between RSTN expression and Q values （P〈0.001） in traumatic group. Conclusion： The expression of RSTN has been greatly increased in the muscular tissue of TBI rats and it was closely related to the index of glycometabolism. RSTN may play an important role in the process of insulin resistance after TBI.

Glucose metabolic abnormality is associated with defective mineral homeostasis in skeletal disorder mouse model

Bone was reported as a crucial organ for regulating glucose homeostasis. In this study, we found that Phex mutant mice(PUG), a model of human X-linked hypophosphatemic rickets(XLH), displayed metabolic abnormality in addition to abnormal phosphate homeostasis, skeletal deformity and growth retardation. Glucose tolerance was elevated with enhanced insulin sensitivity in PUG, though circulating insulin level decreased. Interestingly, bone mineral density defects and glucose metabolic abnormality were both rescued by adding phosphorus- and calcium-enriched supplements in daily diet. Serum insulin level, glucose tolerance and insulin sensitivity showed no differences between PUG and wild-type mice with rescued osteocalcin(OCN) following treatment. Our study suggested that OCN is a potential mediator between mineral homeostasis and glucose metabolism. This investigation brings a new perspective on glucose metabolism regulation through skeleton triggered mineral homeostasis and provides new clues in clinical therapeutics of potential metabolic disorders in XLH patients.

Identification of an allosteric hotspot for additive activation of PPARγ in antidiabetic effects

Thiazolidinediones(TZDs),such as rosiglitazone(RSG),which activates peroxisome proliferator activated receptor-y(PPARy),are a potent class of oral antidiabetic agents with good durability.However,the clinical use of TZDs is challenging because of their side effects,including weight gain and hepatotoxicity.Here,we found that bavachinin(BVC),a lead natural product,additively activates PPARγ with lowdose RSG to preserve the maximum antidiabetic effects while reducing weight gain and hepatotoxicity in db/db mice caused by RSG monotherapy.Structural and biochemical assays demonstrated that an unexplored hotspot around Met329 and Ser332 in helix 5 is triggered by BVC cobinding to RSG-bound PPARy,thereby allosterically stabilizing the active state of the activation-function 2 motif responsible for additive activation with RSG.Based on this hotspot,we discovered a series of new classes of allosteric agonists inducing the activity of TZDs in the same manner as BVC.Together,our data illustrate that the hotspot of PPARγ is druggable for the discovery of new allosteric synergists,and the combination thera py of allosteric synergists and TZD drugs may provide a potential alternative approach to the treatment of type 2 diabetes mellitus.