胰岛素及格列齐特治疗2型糖尿病大鼠肝脏脂质沉积的机制探讨*

 目的：探讨胰岛素及格列齐特治疗2型糖尿病对大鼠肝脏脂质沉积的影响及机制。方法：制备高脂及链脲佐菌素诱导的2型糖尿病大鼠模型,随机分为糖尿病组、胰岛素组和格列齐特组,并设正常对照组。通过肝脏油红O染色观察其肝细胞脂质沉积情况;ELISA检测血清脂联素水平;实时荧光定量PCR检测肝脏脂联素受体1（AdipoR1）mRNA表达;Western blotting检测肝脏腺苷酸活化蛋白激酶（AMPK）、磷酸化的腺苷酸活化蛋白激酶（Thr172p-AMPK）、固醇调节因子结合蛋白1c（SREBP-1c）、磷酸化的固醇调节因子结合蛋白1c（Ser372p-SREBP1-1c）、乙酰辅酶A羧化酶（ACC）、磷酸化的乙酰辅酶A羧化酶（Ser79p-ACC）和免疫球蛋白结合蛋白（BiP）的表达。结果：糖尿病组肝细胞脂质沉积较正常对照组明显增多,胰岛素和格列齐特治疗后肝细胞脂质沉积明显改善。胰岛素治疗后,血清脂联素的水平及肝脏AdipoR1 mRNA水平较糖尿病组和正常对照组显著升高（P＜0.01）,而格列齐特治疗后两者水平恢复至正常对照组水平。Western blotting结果显示,糖尿病大鼠与正常对照组比较,肝脏Thr172p-AMPK/AMPK和Ser372p-SREBP-1c/SREBP-1c和Ser79p-ACC/ACC表达明显降低（P＜0.01）,BiP表达明显升高（P＜0.01）。胰岛素治疗后,Thr172p-AMPK/AMPK和Ser372p-SREBP-1c/SREBP-1c显著升高（P＜0.01）,Ser79p-ACC/ACC和BiP蛋白表达恢复至正常对照组水平。而格列齐特治疗后Thr172p-AMPK/AMPK和Ser372p-SREBP-1c/SREBP-1c恢复至正常对照组水平,BiP蛋白表达显著下降（P＜0.01）,Ser79p-ACC/ACC与糖尿病组比较无明显改善。结论：胰岛素和格列齐特治疗均能通过激活脂联素-AMPK减轻2型糖尿病大鼠肝脏的脂质沉积。但两者作用的分子机制有所不同。胰岛素激活AMPK,通过抑制SREBP-1c表达、直接磷酸化SREBP-1c抑制SREBP-1c入核等短期和长期的作用以及抑制内质网应激影响SREBP-1c,减少脂质合成;而格列齐特仅通过磷酸化的短期作用和抑制内质网应激对SREBP-1c产生影响,且对脂肪酸氧化无作用。     

Differential induction of genes in liver and brown adipose tissue regulated by peroxisome proliferator-activated receptor-alpha during fasting and cold exposure in acyl-CoA dehydrogenase-deficient mice

Mice deficient for either long-chain acyl-CoA dehydrogenase (LCAD-/-) or very-long-chain acyl-CoA dehydrogenase (VLCAD-/-) develop hepatic steatosis upon fasting, due to disrupted mitochondrial fatty acid oxidation. Moreover, neither mouse model can maintain core body temperature when exposed to cold. We investigated the effects of fasting and cold exposure on gene expression in these mice. Non-fasted LCAD-/- mice showed gene expression changes indicative of fatty liver, including elevated mRNA levels for peroxisome proliferator-activated receptor-gamma (PPARgamma) and genes involved in lipogenesis. In LCAD-/- and VLCAD-/- mice challenged with fasting and cold exposure, expression of fatty acid oxidation genes was elevated in liver, consistent with increased PPARalpha activity. This effect was not seen in brown adipose tissue, suggesting that expression of these genes may be regulated differently than in liver. The effect of acute cold exposure on expression of fatty acid oxidation genes was measured in peroxisome proliferator-activated receptor (PPAR)-alpha-deficient mice (PPARalpha-/-) and controls. In PPARalpha-/- mice, basal expression of the acyl-CoA dehydrogenases was reduced in liver but was not altered in brown adipose tissue. While cold altered the expression of PPARgamma, sterol-regulatory element binding protein-1 (SREBP-1), ATP citrate lyase, and the uncoupling proteins in brown adipose tissue from both PPARalpha-/- and control mice, fatty acid oxidation genes were unaffected. Thus, while fatty acid oxidation appears critical for non-shivering thermogenesis, expression of the acyl-CoA dehydrogenases is not influenced by cold exposure. Moreover, mitochondrial fatty acid oxidation genes are not regulated by PPARalpha in brown adipose tissue as they are in liver.     

AMPK as a metabolic switch in rat muscle,liver and adipose tissue after exercise

An increasing body of evidence has revealed that activation of adenosine monophosphate (AMP)‐activated protein kinase (AMPK)‐activated protein kinase increases fatty acid oxidation by lowering the concentration of malonyl coenzyme A (CoA), an inhibitor of carnitine palmitoyl transferase 1. Studies carried out primarily in skeletal muscle suggest that AMPK modulates the concentration of malonyl CoA by concurrently phosphorylating and inhibiting acetyl CoA carboxylase (ACC), the rate limiting enzyme in malonyl CoA synthesis, and phosphorylating and activating malonyl CoA decarboxylase (MCD), an enzyme involved in its degradation. We have recently observed that AMPK and MCD activities are increased and ACC activity diminished in skeletal muscle, liver and, surprisingly, in adipose tissue 30 min following exercise (treadmill run) in normal rats. In liver and adipose tissue these changes were associated with a decrease in the activity of glycerol‐3‐phosphate acyltransferase (GPAT), which catalyses the first committed reaction in glycerolipid synthesis and, which like ACC, is phosphorylated and inhibited by AMPK. Similar changes in ACC, MCD and GPAT were observed following the administration of 5‐aminoimidazole 4‐carboxamide‐riboside (AICAR), further indicating that the exercise‐induced alterations in these enzymes were AMPK‐mediated. Conclusions: (1) AMPK plays a major role in regulating lipid metabolism in multiple tissues following exercise. (2) The net effect of its activation is to increase fatty acid oxidation and diminish glycerolipid synthesis. (3) The relevance of these findings to the regulation of muscle glycogen repletion in the post‐exercise state and to the demonstrated ability of AMPK activation to decrease adiposity and increase insulin sensitivity in rodents remains to be determined.     

AMPK as a metabolic switch in rat muscle,liver and adipose tissue after exercise

An increasing body of evidence has revealed that activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK)-activated protein kinase increases fatty acid oxidation by lowering the concentration of malonyl coenzyme A (CoA), an inhibitor of carnitine palmitoyl transferase 1. Studies carried out primarily in skeletal muscle suggest that AMPK modulates the concentration of malonyl CoA by concurrently phosphorylating and inhibiting acetyl CoA carboxylase (ACC), the rate limiting enzyme in malonyl CoA synthesis, and phosphorylating and activating malonyl CoA decarboxylase (MCD), an enzyme involved in its degradation. We have recently observed that AMPK and MCD activities are increased and ACC activity diminished in skeletal muscle, liver and, surprisingly, in adipose tissue 30 min following exercise (treadmill run) in normal rats. In liver and adipose tissue these changes were associated with a decrease in the activity of glycerol-3-phosphate acyltransferase (GPAT), which catalyses the first committed reaction in glycerolipid synthesis and, which like ACC, is phosphorylated and inhibited by AMPK. Similar changes in ACC, MCD and GPAT were observed following the administration of 5-aminoimidazole 4-carboxamide-riboside (AICAR), further indicating that the exercise-induced alterations in these enzymes were AMPK-mediated. CONCLUSIONS: (1) AMPK plays a major role in regulating lipid metabolism in multiple tissues following exercise. (2) The net effect of its activation is to increase fatty acid oxidation and diminish glycerolipid synthesis. (3) The relevance of these findings to the regulation of muscle glycogen repletion in the post-exercise state and to the demonstrated ability of AMPK activation to decrease adiposity and increase insulin sensitivity in rodents remains to be determined.     

枸骨叶水提物对小鼠肥胖的预防作用及对脂肪分化的影响

目的:研究枸骨叶水提物(ICAE)对高脂饮食(HFD)小鼠肥胖的预防作用及对脂肪分化的影响.方法:本研究采用HFD诱导小鼠肥胖,同时灌胃给予ICAE,以奥利司他(orlistat)为阳性对照药。39只昆明雄性小鼠分成4组,包括对照组(n=10)、肥胖模型组(n=9)、orlistat治疗组(n=10)和ICAE治疗组(n=10)。以体重、腹内和皮下脂肪含量、肝重以及血清甘油三酯(TG)和总胆固醇(TC)水平为指标,观察ICAE对肥胖的预防作用;在实验第5周,连续5 d监测ICAE对小鼠24 h平均摄食量的影响;HE染色观察ICAE对脂肪组织的影响。分离和培养大鼠附睾来源的前脂肪细胞,尼罗红染色观察ICAE对分化脂肪细胞内脂滴形态的影响,Western blot法检测ICAE对细胞内过氧化物酶体增殖物激活受体γ(PPARγ)、脂滴包被蛋白1(Plin1)及激素敏感性脂肪酶(HSL)蛋白表达的影响。结果:ICAE可以显著抑制HFD引起的小鼠体重、腹内和皮下脂肪含量以及肝重的增加(P<0.01),并且显著降低血清TC和TG水平(P<0.01),但是对摄食量无显著影响;HE染色显示...     

Upregulation of AMPK during cold exposure occurs via distinct mechanisms in brown and white adipose tissue of the mouse

AMPK (adenosine monophosphate-activated protein kinase), a key regulator of cellular energy metabolism and whole-body energy balance, is present in brown adipose tissue but its role in regulating the acute metabolic state and chronic thermogenic potential of this metabolically unique tissue is unknown. To address this, the AMPK signalling system in brown and white adipose tissue was studied in C57Bl/6 mice under control conditions, during acute and chronic cold exposure, and during chronic adrenergic stimulation. In control mice AMPK activity in brown adipose tissue was higher than in any tissue yet reported (3-fold the level in liver) secondary to a high level of expression of the α1 isoform. During the first day of cold, a time of intense non-shivering thermogenesis, AMPK activity remained at basal levels. However, chronic (>7 days) cold caused a progressive increase in brown adipose tissue AMPK activity secondary to increased expression of the α1 isoform. To investigate the signalling pathway involved, noradrenaline (norepinephrine) and the β₃-adrenergic-specific agonist CL 316, 243 were given for 14 days. This increased uncoupling protein-1 content in brown adipose tissue, but not AMPK activity. In white adipose tissue 15 days of cold increased α1 AMPK activity 98 ± 20%, an effect reproduced by chronic noradrenaline or CL 316 243. We conclude that chronic cold not only increases AMPK activity in brown and white adipose tissue, but that it does so via distinct signalling pathways. Our data are consistent with AMPK acting primarily as a regulator of chronic thermogenic potential in brown adipose tissue, and not in the acute activation of non-shivering thermogenesis.     

AMPK，SIRT1与能量代谢

在调节细胞能量状态的蛋白激酶级联反应中,AMP 激活的蛋白激酶(AMPK) 是其中枢组成部分,AMPK的活性受AMP/ATP比值的调节。沉默信息调节因子2相关酶1（SIRT1）作为一种NAD+依赖的组蛋白去乙酰化酶,同样在调节细胞能量代谢中起着重要作用。AMPK与SIRT1相互起调控作用,阐明AMPK与SIRT1作用的上下游信号通路有可能成为新的治疗代谢疾病作用靶点。     

游离脂肪酸混合物对肝细胞脂毒性及脂代谢相关基因表达的影响

目的:研究游离脂肪酸(FFA)混合物对肝细胞L-02的脂毒性及脂代谢相关基因表达的影响。方法:正常肝细胞L-02分别用正常培养基和0.5、1、2 mmol/LFFA混合物(油酸和软脂酸的比例为2:1)培养24 h后,尼罗红染液室温避光染色,激光共聚焦显微镜及流式细胞仪确定细胞内脂质堆积情况。组织细胞酶法测定试剂盒测定细胞内甘油三酯含量。MTT法分析细胞存活率,Annexin V-PI凋亡检测试剂盒分析肝细胞的凋亡情况,丙氨酸氨基转移酶(ALT)和天冬氨酸氨基转移酶(AST)测定试剂盒分别检测培养液中ALT和AST活性。实时定量PCR技术检测脂代谢相关的脂肪分化相关蛋白(ADRP)和固醇调节元件结合蛋白1(SREBP-1)的mRNA表达情况。结果:各浓度FFAs混合物均可剂量依赖性增加肝细胞脂肪堆积和肝细胞甘油三酯含量,且1 mmol/LFFA混合物可增高肝细胞的甘油三酯含量2.6倍,与非酒精性脂肪肝病人的变化基本相同。2 mmol/LFFA混合物可降低肝细胞L-02细胞存活率并诱导细胞凋亡,而0.5 mmol/L和1 mmol/LFFA混合物对细胞无明显影响。与对照组相比,各浓度FFA混合物对细胞上清中ALT和AST活性无明显影响。1 mmol/LFFA混合物作用后可分别上调肝细胞的ADRP和SREBP-1 mRNA的表达2.660和2.758倍。结论:FFA混合物可诱导肝细胞L-02脂肪变性且2mmol/LFFA混合物可造成轻度细胞损伤。脂代谢相关基因ADRP和SREBP-1表达上调与FFA混合物诱导的脂肪变性相关。     

3,4-二羟基苯乙酮通过AMPK途径降低肝细胞及肝脏组织的甘油三酯含量

目的:探讨3,4-二羟基苯乙酮(3,4-dihydroxyacetophenone,3,4-DHAP)调节肝细胞脂质代谢的机制。方法:传代培养人正常肝细胞L02,分为正常对照组、模型组、3,4-DHAP组和辛伐他汀组;药物处理8 h后收集细胞;应用试剂盒检测细胞内甘油三酯(triglyceride,TG)含量; RT-qPCR检测细胞中AMP活化蛋白激酶(AMPactivated protein kinase,AMPK)的mRNA表达水平;采用Western blot法检测细胞AMPK、磷酸化AMPK(phosphorylated AMPK,p-AMPK)、磷酸化固醇调节元件结合蛋白1c(phosphorylated sterol regulatory element binding protein 1c,p-SREBPs-1c)和磷酸化乙酰辅酶A羧化酶(phosphorylated acetyl-CoA carboxylase,p-ACC)的蛋白水平。高脂饲养新西兰大白兔,随机分为正常对照组、模型组、3,4-DHAP组和辛伐他汀组,给药处理12周后,收集肝脏标本,油红O染色;应用试剂盒分析各组TG含量;采用Western blot法检测肝脏组织中AMPK、p-AMPK、p-SREBP-1c和p-ACC的蛋白水平。结果:在细胞水平,3,4-DHAP处理后,与模型组比较,TG含量明显降低,AMPK在mRNA及蛋白水平的表达皆显著增加,AMPK磷酸化明显增加,即活性明显增强; SREBP-1c及ACC磷酸化亦显著增多。在动物实验中,经3,4-DHAP处理后,肝脏组织中的TG含量明显减少,AMPK蛋白表达显著增多、p-AMPK、p-SREBP-1c和pACC蛋白水平明显升高。结论:3,4-DHAP可能通过AMPK途径降低肝细胞及肝脏组织中的TG。     

SREBP-1c, regulated by the insulin and AMPK signaling pathways, plays a role in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease whose prevalence has increased markedly. We reported previously that fatty acid synthesis was enhanced in NAFLD with the accumulation of fatty acids. To clarify the disorder, we evaluated the expression of genes regulating fatty acid synthesis by real-time PCR using samples from NAFLD (n=22) and normal liver (control; n=10). A major regulator of fatty acids synthesis is sterol regulatory element-binding protein-1c (SREBP-1c). Its expression was significantly higher in NAFLD, nearly 5-fold greater than the controls. SREBP-1c is positively regulated by insulin signaling pathways, including insulin receptor substrate (IRS)-1 and -2. In NAFLD, IRS-1 expression was enhanced and correlated positively with SREBP-1c expression. In contrast, IRS-2 expression decreased by 50% and was not correlated with SREBP-1c. Forkhead box protein A2 (Foxa2) is a positive regulator of fatty acid oxidation and is itself negatively regulated by IRSs. Foxa2 expression increased in NAFLD and showed a negative correlation with IRS-2, but not with IRS-1, expression. It is known that SREBP-1c is negatively regulated by AMP-activated protein kinase (AMPK) but expression levels of AMPK in NAFLD were almost equal to those of the controls. These data indicate that, in NAFLD, insulin signaling via IRS-1 causes the up-regulation of SREBP1-c, leading to the increased synthesis of fatty acids by the hepatocytes; negative feedback regulation via AMPK does not occur and the activation of Foxa2, following a decrease of IRS-2, up-regulates fatty acid oxidation.     

SREBP-1和SREBP-2在Ⅰ型糖尿病大鼠肾脏中的表达

目的:探讨糖尿病大鼠肾脏脂质沉积和固醇调节元件结合蛋白-1和-2（SREBP-1, SREBP-2）的表达。方法:以Wistar大鼠建立链脲佐菌素Ⅰ型糖尿病模型,测定肾组织甘油三酯和胆固醇含量,采用油红O染色检测脂质沉积的定位;用免疫组织化学和Western blotting检测SREBP-1、SREBP-2蛋白的表达;SREBP-1 mRNA测定采用原位杂交技术。结果:成功构建了Ⅰ型糖尿病大鼠模型,甘油三酯含量在1、2、4、8周均出现了明显升高,而肾脏胆固醇含量没有明显变化。油红O检测发现糖尿病大鼠肾脏近曲小管上皮细胞内出现明显脂滴,而肾小球内未见有脂滴染色。免疫组织化学检测发现,SREBP-1定位于糖尿病大鼠肾脏近曲小管上皮细胞胞浆,肾小球内未见有棕黄色颗粒。Western blotting进一步检测了SREBP-1蛋白的表达,结果发现糖尿病大鼠肾组织在4个时点均呈高表达,相似地,SREBP-1 mRNA的检测应用原位杂交技术,结果证实其定位于肾小管上皮细胞胞浆,而肾小球内未见着色。与正常对照组相比,糖尿病组大鼠肾脏SREBP-1 mRNA表达明显升高,差异显著。结论:Ⅰ型糖尿病大鼠肾小管上皮细胞SREBP-1 mRNA和蛋白表达升高可能参与了肾脏代谢异常。     

Re-evaluation of fatty acid metabolism-related gene expression in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent causes of abnormal liver dysfunction, and its prevalence has markedly increased. We previously evaluated the expression of fatty acid metabolism-related genes in NAFLD and reported changes in expression that could contribute to increased fatty acid synthesis. In the present study, we evaluated the expression of additional fatty acid metabolism-related genes in larger groups of NAFLD (n=26) and normal liver (n=10) samples. The target genes for real-time PCR analysis were as follows: acetyl-CoA carboxylase (ACC) 1, ACC2, fatty acid synthase (FAS), sterol regulatory element-binding protein 1c (SREBP-1c), and adipose differentiation-related protein (ADRP) for evaluation of de novo synthesis and uptake of fatty acids; carnitine palmitoyltransferase 1a; (CPT1a), long-chain acyl-CoA dehydrogenase (LCAD), long-chain L-3-hydroxyacylcoenzyme A dehydrogenase alpha (HADHalpha), uncoupling protein 2 (UCP2), straight-chain acyl-CoA oxidase (ACOX), branched-chain acyl-CoA oxidase (BOX), cytochrome P450 2E1 (CYP2E1), CYP4A11, and peroxisome proliferator-activated receptor (PPAR)alpha for oxidation in the mitochondria, peroxisomes and microsomes; superoxide dismutase (SOD), catalase, and glutathione synthetase (GSS) for antioxidant pathways; and diacylglycerol O-acyltransferase 1 (DGAT1), PPARgamma, and hormone-sensitive lipase (HSL) for triglyceride synthesis and catalysis. In NAFLD, although fatty acids accumulated in hepatocytes, their de novo synthesis and uptake were up-regulated in association with increased expression of ACC1, FAS, SREBP-1c, and ADRP. Fatty acid oxidation-related genes, LCAD, HADHalpha, UCP2, ACOX, BOX, CYP2E1, and CYP4A11, were all overexpressed, indicating that oxidation was enhanced in NAFLD, whereas the expression of CTP1a and PPARalpha was decreased. Furthermore, SOD and catalase were also overexpressed, indicating that antioxidant pathways are activated to neutralize reactive oxygen species (ROS), which are overproduced during oxidative processes. The expression of DGAT1 was up-regulated without increased PPARgamma expression, whereas the expression of HSL was decreased. Our data indicated the following regarding NAFLD: i) increased de novo synthesis and uptake of fatty acids lead to further fatty acid accumulation in hepatocytes; ii) mitochondrial fatty acid oxidation is decreased or fully activated; iii) in order to complement the function of mitochondria (beta-oxidation), peroxisomal (beta-oxidation) and microsomal (omega-oxidation) oxidation is up-regulated to decrease fatty acid accumulation; iv) antioxidant pathways including SOD and catalase are enhanced to neutralize ROS overproduced during mitochondrial, peroxisomal, and microsomal oxidation; and v) lipid droplet formation is enhanced due to increased DGAT expression and decreased HSL expression. Further studies will be needed to clarify how fatty acid synthesis is increased by SREBP-1c, which is under the control of insulin and AMP-activated protein kinase.     

小檗碱激活AMPK抑制3T3-L1脂肪细胞分化

目的 探讨小檗碱对3T3-L1脂肪分化的作用是否与激活腺苷酸活化蛋白激酶（AMPK）有关.方法 在3T3-L脂肪细胞分化全程加入小檗碱,以油红O染色检测3T3-L1脂肪细胞胞浆中脂肪的堆积,实时定量PCR检测过氧化物酶体增殖物激活受体γ2（PPARγ2）、CCAAT增强子结合蛋白α（CEBPα）和AMPK的mRNA表达,以Western印迹法检测AMPK和乙酰辅酶A羧化酶（ACC）的磷酸化水平.结果 小檗碱剂量依赖性地抑制3T3-L1脂肪细胞分化,10 μmol/L小檗碱几乎完全抑制胞浆中脂肪的堆积.5 μmol/L小檗碱在脂肪细胞诱导分化1、3、5、7d后均显著降低CEBPα mRNA表达（P〈0.05或P〈0.01）,诱导分化3、5、7d时显著降低PPARγ2的mRNA表达（P〈0.05或P〈0.01）.AMPK的mRNA水平在分化过程中未受小檗碱的明显影响,而小檗碱明显增加其蛋白磷酸化水平,其下游靶基因ACC磷酸化水平也明显增加.结论 小檗碱抑制3T3-L1脂肪细胞的分化可能与其激活AMPK有关.     

AMPK通过增强心肌脂肪酸氧化抑制大鼠心肌肥厚

目的： 探讨单磷酸腺苷（AMP）激活的蛋白激酶（AMPK）对心肌肥厚的影响及可能涉及的作用机制。方法： 通过对大鼠行腹主动脉缩窄术（TAC）引起压力负荷增加，造成心肌肥厚的模型。术后24 h起经皮下注射AMPK的特异性激活剂AICAR(0.5 mg·kg-1·d-1)直至术后7周。处死动物前，对大鼠进行超声心动学指标的检测和血清游离脂肪酸浓度测定；处死动物，取心脏称重后计算心脏重/体重比值，测量心肌细胞的平均直径、心肌中的游离脂肪酸含量、过氧化体增殖物激活型受体α（PPARα）和肉碱棕榈酰转移酶（CPT-I）的mRNA表达。结果： （1）心肌肥厚+AICAR组大鼠的心脏重/体重比值、心肌细胞平均直径、血清及心肌中游离脂肪酸的浓度明显低于心肌肥厚对照组；（2）心肌肥厚+AICAR组大鼠心肌PPARα及CPT-I的mRNA表达明显高于心肌肥厚对照组；(3) 心肌肥厚+AICAR组大鼠心脏超声心动学指标：左室后壁舒张末期厚度、左室舒张、收缩末期内径 (PWT, LVDD, LVSD) 低于心肌肥厚对照组，左室短轴缩短率 (FS%) 则高于心肌肥厚对照组。结论： 活化的AMPK可能通过增强心肌脂肪酸氧化从而抑制压力负荷增加引起的心肌肥厚。     

罗格列酮对高脂喂养大鼠肾小管上皮细胞SREBP-1、TGF-β1表达和细胞外基质沉积的影响

目的： 探讨高脂饮食对大鼠肾小管上皮细胞固醇调节元件结合蛋白-1（SREBP-1）、转化生长因子-β1（TGF-β1）表达和细胞外基质（ECM）沉积的影响以及罗格列酮的干预治疗。方法: 给予Wistar大鼠高脂饲料喂养并进行罗格列酮灌胃治疗3个月,进行血液生化检测。油红O检测肾脏脂质沉积情况,Masson染色检测肾脏细胞外基质沉积,SREBP-1、TGF-β1和FN蛋白表达检测采用免疫组织化学和Western blotting,原位杂交用于检测SREBP-1 mRNA的表达。结果: 罗格列酮有效避免了高脂饮食导致的大鼠血糖、血胰岛素和血甘油三酯的升高;高脂喂养组大鼠肾脏小管上皮细胞内出现了明显脂滴,小管外间质细胞外基质沉积增多,罗格列酮干预减少了脂滴和基质沉积;SREBP-1蛋白和RNA在高脂喂养组均呈高表达,明显强于正常对照组,经罗格列酮处理表达有显著下降,蛋白前体和成熟片段分别下降了27.39%和27.32%;致纤维化因子TGF-β1和细胞外基质成分之一的纤维黏连蛋白（FN）在高脂喂养大鼠肾脏的高表达均被罗格列酮干预治疗所避免,TGF-β1表达在罗格列酮干预组较高脂组降低了19.14%。结论: 罗格列酮可有效避免高脂饮食造成的大鼠肾小管上皮细胞SREBP-1、TGF-β1高表达、脂质沉积和细胞外基质堆积。