下丘脑STAT3在非酒精性脂肪性肝病大鼠发病中的作用及降脂颗粒的干预

目的:观察非酒精性脂肪肝大鼠下丘脑STAT3蛋白表达和组成性激活的改变,以及中药降脂颗粒对其干预作用.方法:高脂饲料制备非酒精性脂肪肝大鼠模型,待造模成功后将大鼠随机分为模型对照组(n=10)、辛伐他汀组(n=10)、降脂颗粒组(n=10),每日进行ig药物干预,4 wk,并设空白对照组(n=8).比色法检测血清TG、TC;HE染色观察观察肝组织脂肪变和炎症;Western blot检测下丘脑磷酸化STAT3蛋白表达,EMSA检测下丘脑STAT3的组成性激活状态.结果:磷酸化STAT3蛋白表达及其组成性激活在非酒精性脂肪肝大鼠均明显降低,降脂颗粒用药组及辛伐他汀组能下调大鼠血清TG(0.54±0.09 mmol/L,0.68±0.08 mmol/Lvs 0.84±0.09 mmol/L,均P<0.05)、TC(1.85±0.31 mmol/L,2.08±0.30 mmol/L vs 2.84±0.30mmol/L,均P<0.05)水平,减轻肝脂肪变(2.26±0.52,2.57±0.67 vs 3.10±0.57,均P<0.05)和炎症程度(0.68±0.67,0.95±0.6 vs 1.52±0.71,均P<0.05);上调下丘脑组织磷酸化STAT3蛋白表达及其组成性激活.结论:STAT3在非酒精性脂肪肝大鼠下丘脑组织表达和激活明显下降,中药降脂颗粒对非酒精性脂肪肝有很好的治疗作用,并可上调STAT3的表达和组成性激活.     

中药降脂颗粒对非酒精性脂肪肝大鼠肝脏瘦素受体mRNA及P-JAK2/P-STAT3的影响

目的:观察降脂颗粒对非酒精性脂肪肝大鼠的治疗作用及其对血清瘦素、肝组织瘦素受体mRNA、P-JAK2/P-STAT3蛋白含量表达的影响.方法:将60只SD♂大鼠,随机分为空白组(正常饮食)和造模组(高脂饮食).待造模成功后将造模组大鼠随机分为模型对照组、降脂颗粒低、中、高剂量组和东宝甘泰组.治疗4 wk后行肝组织生化和病理学检测,并同时应用ELISA试剂盒检测血清瘦素,RT-PCR法检测肝组织瘦素受体mRNA表达,应用Western blot检测肝组织P-JAK2和P-STAT3蛋白的表达.结果:低、中、高剂量组降脂颗粒能明显降低非酒精性脂肪肝大鼠模型肝脂(TG和TC)水平,改善脂肪变性,降低肝脏炎症反应,并能明显降低血清瘦素高水平状态(193.02±23.8 ng/L,163.97±31.38 ng/L,147.83±17.59 ng/L vs 317.22±39.26 ng/L,P＜0.01),改善瘦素抵抗,同时增加瘦素受体mRNA的表达(1.87±0.06,2.20±0.04,2.78±0.04 vs 1.50±0.05,P＜0.01),增加肝组织P-JAK2和P-STAT3蛋白的含量(119.88±2.98,123.45±0.68,124.34±3.42 vs 113.15±1.27,P＜0.01;94.15±0.78,100.18±3.33,101.94±2.20 vs 89.06±0.69,P＜0.01).结论:降脂颗粒对非酒精性脂肪肝大鼠肝脏脂质和炎症有较好的治疗作用,其可能机制是改善瘦素抵抗,增加肝脏瘦素受体mRNA表达及P-JAK2,P-STAT3蛋白含量.     

瘦素及其受体在大鼠酒精性肝病形成过程中的动态变化及意义

目的:观察酒精性肝病形成中大鼠血清瘦素水平、肝组织瘦素及其受体表达的动态变化,探讨瘦素及其受体在酒精性肝病形成中的发病机制.方法:SD雄性大鼠随机分为正常组和模型组,以白酒-玉米油-吡唑混合液灌胃建立酒精性肝病动物模型,分别在4、8、14周末光镜观察大鼠肝脏组织学变化情况,免疫组化法检测肝组织瘦素及其受体的表达,ELISA法检测大鼠血清瘦素水平.结果:模型组大鼠肝组织在4周时出现轻度脂肪变及腺泡内个别点状坏死灶,8周时脂肪变程度加重、腺泡内点状坏死灶增多、门管区炎细胞浸润,14周脂肪变和炎症程度进一步加重;模型组大鼠4周时,肝组织瘦素及其受体表达、血清瘦素水平与同期正常组比差异无显著性意义(P＞0.05),随着肝脏损伤程度的加重,三者均明显增加(P＜0.05,P＜0.01);肝组织中瘦素及其受体表达水平与肝脏脂肪变及炎症程度均呈明显正相关.结论:在白酒-玉米油-吡唑混合液灌服复制的大鼠酒精性肝病形成过程中,瘦素及其受体表达增加,且随肝脏损伤程度的加重而逐渐增加,提示其参与了酒精性肝病的发生发展.     

强肝胶囊对非酒精性脂肪肝大鼠肝脏瘦素受体及P-JAK2和P-STAT3蛋白的影响

[目的]观察强肝胶囊对非酒精性脂肪肝（NAFLD）大鼠的治疗作用,及其对血清瘦素、肝组织瘦素受体mRNA、P-JAK2和P-STAT3蛋白表达的影响,探讨强肝胶囊治疗NAFLD的可能机制。[方法]高脂饲料制备SD雄性大鼠NAFLD模型,随机分为空白组和造模组。待造模成功后将造模组大鼠随机分为模型对照（模型）组、强肝胶囊组和辛伐他汀组。治疗4周后行肝组织病理学检测,并同时应用ELISA试剂盒检测血清瘦素,RT-PCR法检测肝组织瘦素受体mRNA表达,western blot检测肝组织P-JAK2、P-STAT3蛋白的表达。[结果]强肝胶囊能明显降低NAFLD模型大鼠肝组织三酰甘油、总胆固醇的水平,改善脂肪变性,降低肝脏炎症反应,并能明显降低血清瘦素高水平状态,改善瘦素抵抗,同时增加瘦素受体mRNA的表达,增加肝组织P-JAK2、p-STAT3蛋白的水平。[结论]强肝胶囊对NAFLD大鼠肝脏脂质和炎症有较好的治疗作用,其可能机制是通过改善瘦素抵抗,增加肝脏瘦素受体mRNA表达及P-JAK2、P-STAT3蛋白水平而完成的。     

瘦素及其受体在非酒精性脂肪性肝炎发病机制中的作用

目的探讨瘦素(LP)及其受体在非酒精性脂肪性肝炎(NASH)大鼠肝组织中的表达及意义。方法采用高脂饮食制备Wistar大鼠NASH模型;ELISA法测定大鼠血清瘦素(LP)浓度;全自动生化分析仪检测各组大鼠血清空腹血糖(FBG)、甘油三酯(TG)水平;比色法测定血清游离脂肪酸(FFA)含量;放射免疫法测定血清胰岛素(FINS)及肿瘤坏死因子α(TNF-α)水平,并计算胰岛素抵抗指数(HOMA-IR);HE、苏丹Ⅳ、Masson三重染色光镜下观察肝组织病理变化;逆转录聚合酶链反应(RT-PCR)和免疫组织化学染色分别检测肝组织OB-RbmRNA和蛋白的表达。结果模型组大鼠血清瘦素、TG、FFA、HOMA-IR、TNF-α均较正常对照组明显升高;模型组大鼠肝组织表现为不同程度的脂肪变性、炎症坏死及窦周纤维化;肝组织OB-RbmRNA和蛋白的表达则较正常对照组显著减弱;相关分析显示:模型组大鼠肝组织瘦素受体蛋白表达与与血清瘦素水平、血游离脂肪酸、TNF-α、胰岛素敏感指数、肝细胞脂肪变性、炎症活动度呈显著负相关,相关系数r分别为-0.83、-0.71、-0.74、-0.65、-0.83、-0.87,P<0.01。多元线性回归分析显示,瘦素受体表达减弱是肝脏脂肪变性的独立影响因素。结论肝组织瘦素受体表达减弱是NASH瘦素抵抗的重要病理机制之一,瘦素抵抗与胰岛素抵抗相互作用,共同促进了NASH的发生发展。     

大黄素和小檗碱对高浓度瘦素作用下HepG2细胞瘦素受体mRNA表达的影响

目的:探讨大黄素、小檗碱改善非酒精性脂肪肝患者体内高瘦素水平的作用及机制.方法:用MTT法筛选大黄素、小檗碱作用于HepG2细胞实验浓度,在HepG2细胞中加入高浓度的瘦素(10-6 mol/L)作为模型组,在模型组中分别加入大黄素、小檗碱及地塞米松,并设对照组进行比较.用RT-PCR检测细胞上瘦素长型受体及短型受体mRNA的表达水平.结果:模型组细胞上瘦素长型受体及短型受体mRNA的表达水平较对照组显著下调(P<0.01),大黄素、小檗碱及地塞米松组较模型组显著上调(P<0.01),较对照组无明显改变(P>0.05).结论:大黄素和小檗碱具有通过上调瘦素受体mRNA的表达来治疗高浓度瘦素诱导机体产生非酒精性脂肪肝的作用.     

祛脂调肝中药对非酒精性脂肪肝SD大鼠瘦素和肿瘤坏死因子-α的影响

目的探讨祛脂调肝中药对非酒精性脂肪肝大鼠瘦素和肿瘤坏死因子(TNF)-α的影响。方法高脂饲料制备SD大鼠非酒精性脂肪肝模型,随机分为正常组、模型组、祛脂调肝高、低剂量组和水飞蓟素组,治疗4 w后肝组织生化和病理学检测。结果祛脂调肝中药能显著改善非酒精性脂肪肝大鼠肝指数,降低三酰甘油(TG)、总胆固醇(TC)、游离脂肪酸(FFA)含量,保护肝细胞,纠正脂质代谢紊乱,降低肝脏炎症,从病理组织学上改善非酒精性脂肪肝大鼠瘦素、TNF-α水平。结论祛脂调肝中药降低非酒精性脂肪肝大鼠肝脏组织瘦素、TNF-α水平,减轻胰岛素抵抗,阻止病情的发展。     

三七总皂苷对大鼠非酒精性脂肪肝模型胰岛素抵抗及瘦素受体表达的影响

目的 研究三七总皂苷对大鼠脂肪肝模型胰岛素抵抗（IR）及瘦素受体表达的影响，探讨其治疗脂肪肝的作用机制。方法 利用高脂饮食诱发大鼠非酒精性脂肪肝（NAFLD）模型；称各组大鼠体重、肝湿重，计算肝指数；放射免疫法测定血清瘦素（LP）和胰岛素（FINS）浓度，全自动生化分析仪测空腹血糖，计算空腹下胰岛素抵抗指数；免疫组化法检测瘦素受体（OB—R）在肝组织中的表达，图像分析，计算平均光密度值。结果 三七总皂苷高、低剂量组体重及肝指数与模型组比较明显下降（P〈0.05），瘦素水平和胰岛素抵抗指数与模型组比较均有明显降低（P〈0.05），模型组肝组织OB—R表达比正常组明显增强（P〈0.05），三七总皂苷高、低剂量均可下调模型组大鼠OB—R的表达，且高剂量组最为明显（P〈0．05）。结论 三七总皂苷治疗NAFLD有效，并通过降低肝指数、血清瘦素水平，改善胰岛素抵抗和下调瘦素受体表达而起到治疗NAFLD的作用。     

瘦素受体基因Gln223Arg多态性与非酒精性脂肪性肝病的关系

目的 探讨瘦素受体基因多态性与非酒精性脂肪肝患者临床表型间的关系.方法 以非酒精性脂肪肝患者和正常对照人群为研究对象,应用聚合酶链反应及限制性片段长度多态性方法(PCR-RFLP),对167例中国人(包括85例非酒精性脂肪肝患者和82例正常对照)的瘦素受体基因Gln223Arg进行研究,同时进行临床参数的检测.结果 (1)非酒精性脂肪肝患者和正常对照组人群中Gln223Arg基因型频率和等位基因频率差异无显著性(P>0.05).(2)非酒精性脂肪肝男性患者中AA AG基因型者TC、BMI高于GG基因型(P<0.05).(3)进一步用Logistic回归分析发现:在非酒精性脂肪肝男性患者中该基因变异与TC相关(P=0.019).结论 非酒精性脂肪肝男性患者瘦素受体基因Gln223Arg多态性与TC水平相关.瘦素受体基因Gln223Arg可能参与非酒精性脂肪肝的脂质代谢.     

贞清方对2型糖尿病并发非酒精性脂肪肝大鼠LXRα表达的影响

目的:探讨贞清方对2型糖尿病非酒精性脂肪肝的治疗作用及可能机制.方法:高脂高糖饮食结合小剂量链脲佐菌素(STZ)腹腔注射建立2型糖尿病并发非酒精性脂肪肝大鼠模型.将成模大鼠随机分为模型组、贞清方治疗组和女贞子治疗组( n= 8),并设立正常对照组( n = 10),灌胃治疗8 wk.比较喂养4、8和16 wk时各组大鼠空腹血糖(FBG)、血清甘油三酯(TG)、总胆固醇(TC)、胰岛素(FINs)和胰岛素敏感指数(ISI)的变化.并于喂养16 wk时观察各组大鼠肝脏指数、TG含量和血清丙氨酸转氨酶(ALT)的水平以及病理变化.用PCR法观察大鼠肝X受体(LXRα)及其下游固醇调节元件结合蛋白-1c(SREBP-1c) mRNA的表达,免疫组织化学法观察肝脏LXRα蛋白的表达.结果:灌胃干预8 wk后,与正常组相比,模型组大鼠FBG、血清TG、肝脏指数及肝脏TG含量明显升高(均P<0.01),胰岛素敏感性明显降低( P<0.01),肝脏脂肪变明显加重,肝脏LXRα mRNA、SREBP-1c mRNA和LXRα蛋白的表达明显增多(均P<0.01).与模型组相比,贞清方治疗组大鼠FBG水平、血清TG水平、肝脏指数及肝脏TG含量明显降低(10.94±3.33 mmol/L vs 16.67±4.33 mmol/L; 0.79±0.27 mmol/L vs 1.33±0.33 mmol/L; 5.72±0.81vs 7.61±1.24; 0.041±0.0110 mmol/g vs 0.059±0.0160 mmol/g,均P<0.01),肝脏脂肪变明显改善,肝脏LXRα mRNA、SREBP-1c mRNA和LXRα蛋白的表达明显减少(0.75±0.11 vs1.23±0.17,0.68±0.16 vs 1.07±0.14,0.220±0.071 vs 0.334±0.037,均P<0.01).结论:贞清方对2型糖尿病性非酒精性脂肪肝具有一定的治疗作用,且其治疗作用可能与贞清方能下调非酒精性脂肪肝组织LXRα的表达有关.     

Acute leptin deficiency, leptin resistance, and the physiologic response to leptin withdrawal

Food restriction and weight loss result in reduced plasma leptin, which is associated with a pleiotropic biologic response. However, because weight loss itself is also associated with changes in numerous other humoral and metabolic signals, it can be difficult to determine the precise features of the biologic response to acute leptin deficiency. To study this response in the absence of changes in nutritional state, we have developed a protocol that allows such analysis in normal, non-food-restricted animals. Wild-type mice are treated with high-dose leptin until fat mass is depleted and, as a consequence, endogenous leptin production is reduced. At this point, exogenous leptin is abruptly withdrawn, thus inducing a state of leptin deficiency in otherwise normal mice. Leptin deficiency is sustained by feeding the animals only as much as they consumed voluntarily before leptin withdrawal. The biologic response to leptin deficiency induced in this manner includes altered neuropeptide levels, decreased energy expenditure, and impaired reproductive and immune function. Replacement of leptin at physiological concentrations after withdrawal of high-dosage leptin blunts, but does not completely block, the hyperphagia and weight regain caused by acute leptin deficiency, nor does it correct the resulting reproductive and immune dysfunction. This suggests that high-dosage leptin treatment induces a state of partial leptin resistance. In aggregate, these studies establish the role of acute hypoleptinemia in regulating energy balance, the immune system, and reproductive function, and further suggest that high-dosage leptin treatment can induce a state of acquired leptin resistance.     

Monitoring leptin activity using the chicken leptin receptor

We report on the construction of a leptin bioassay based on the activation of chicken leptin receptor in cultured cells. A human embryonic kidney (HEK)-293 cell line, stably transfected with the full-length cDNA of chicken leptin receptor together with a STAT3-responsive reporter gene specifically responded to recombinant human and Xenopus leptins. The observed higher sensitivity of chicken leptin receptor to the former is in agreement with the degree of sequence similarity among these species (about 60 and 38% identical amino acids between humans and chickens, and between humans and Xenopus respectively). The specific activation of signal transduction through the chicken leptin receptor, shown here for the first time, suggests that the transition of Gln269 (implicated in the Gln-to-Pro Zucker fatty mutation in rats) to Glu in chickens does not impair its activity. Analysis of leptin-like activity in human serum samples of obese and lean subjects coincided well with leptin levels determined by RIA. Serum samples of pre- and post partum cows showed a tight correlation with the degree of adiposity. However, specific activation of the chicken leptin receptor in this assay was not observed with serum samples from broiler or layer chickens (representing fat and lean phenotypes respectively) or with those from turkey. Similar leptin receptor activation profiles were observed with cells transfected with human leptin receptor. Further work is needed to determine whether the lack of leptin-like activity in the chicken serum samples is due to a lack of leptin in this species or simply to a serum level of leptin that is below the detection threshold.     

Possible involvement of leptin and leptin receptor in developing gastric adenocarcinoma

AIM: To investigate the expression of leptin and leptin receptor (ob-R) in intestinal-type gastric cancer and precancerous lesions, and to explore the possible mechanism and role of the leptin system in developing intestinal-type gastric adenocarcinoma. METHODS: Immunohistochemistry was performed to examine the expression of leptin and leptin receptor in archival samples of gastric adenocarcinoma and preneoplastic lesions, including intestinal metaplasia and mild to severe gastric epithelial dysplasia. Positive staining was identified and percentage of positive staining was graded. RESULTS: Dual expression of leptin and leptin receptor were detected in 80% (16/20) intestinal metaplasia, 86.3% (25/30) mild gastric epithelial dysplasia, 86.7% (26/30) moderate gastric epithelial dysplasia, 93.3% (28/30) severe gastric epithelial dysplasia, 91.3% (55/60) intestinal-type gastric adenocarcinoma and 30.0% (9/30) diffuse-type gastric carcinoma. The percentage of dual expression of leptin and leptin receptor in intestinal-type gastric adenocarcinoma was significantly higher than that in diffuse-type gastric adenocarcinoma (x2 = 37.022, CONCLUSION: Our results indicate the presence of an autocrine loop of leptin system in the development of intestinal-type gastric adenocarcinoma.     

Congenital leptin deficiency: diagnosis and effects of leptin replacement therapy

To describe our 10-year experience in treating leptin-deficient humans. Three adults and one boy presented with childhood-onset morbid obesity, hypogonadism and family history of obesity and early death. Serum leptin was inappropriately low. A recessive C105T leptin gene mutation was identified. Metabolic and endocrine assessments were conducted, before and while on and off leptin. The adults' body mass index decreased from 51.2 ± 2.5 to 29.5 ± 2.8 kg/m(2). Serum lipids normalized, insulin resistance decreased, and one of the initially diabetic females became normoglycemic. Hypogonadotropic hypogonadism was reversed, and other changes were observed in the adrenal, sympathetic, somatotropic and thyroid functions. Leptin replacement therapy reverses endocrine and metabolic alterations associated with leptin deficiency. Some of these results may be extrapolated to other diseases.