Cilnidipine Improves Insulin Sensitivity in the Otsuka Long-Evans Tokushima Fatty Rat, a Model of Spontaneous NIDDM

Summary. Among the antihypertensive drugs, fast-acting Ca²⁺ antagonists have been reported to worsen insulin sensitivity. This effect may be attributable to reflex increases in sympathetic activity. On the other hand, however, it has been reported that long-acting, dihydropiridine Ca²⁺ antagonists improve insulin-resistance. The purpose of this study was to investigate whether cilnidipine, another long-acting dihydropidine Ca²⁺ antagonist, improves insulin sensitivity in Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of spontaneous NIDDM. 25 weeks OLETF rats were divided into the following groups; normal-diet group, cilnidipine-supplemented group (cilnidipine 3mg/kg/day) and angiotensin II receptor antagonist CS-866-supplemented group (CS-866 1mg/kg/day). As a non-diabetic control, we used Long-Evans-Tokushima-Otsuka rats (non-diabetic rats). Glucose infusion rate (GIR), an index of insulin resistance, as measured by the hyperinsulinemic euglycemic clamp technique was significantly decreased in OLETF rats. Cilnidipine-treatment partially but significantly improved insulin sensitivity in addition to systolic blood pressure in OLETF rats at 30 weeks of age, although it did not decrease accumulation of abdominal fat or serum levels of glucose or insulin. CS-866, an angiotensin 2 receptor antagonist, which lowers blood pressure through a different mechanism, did not improve insulin resistant states in OLETF rats. These results suggest that cilnidipine has a beneficial effect on insulin-resistance together with the antihypertensive effect.     

Effect of pinealectomy on plasma levels of insulin and leptin and on hepatic lipids in type 2 diabetic rats

We previously reported that pharmacological melatonin administration to type 2 diabetic rats reduces hyperinsulinemia and improves the altered fatty-acid metabolism. To determine whether melatonin deficiency exacerbates diabetes-associated conditions, we investigated the effect of pinealectomy (i.e. melatonin-deficiency) on plasma hormone levels and lipid metabolism in type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. We compared levels of insulin and leptin, and hepatic lipids in pinealectomized OLETF (PO) rats, sham-operated OLETF (SO) rats and sham-operated healthy Long-Evans Tokushima Otsuka (LETO) (SL) rats 16 and 30 wk after the operation. Plasma glucose and triglycerides were increased in SO and PO rats 30 wk after operation compared with age-matched SL rats. Pinealectomy caused an increase in free cholesterol among the plasma lipids, as compared with SO rats. Sixteen weeks after pinealectomy, typical hyperinsulinemia was observed in PO rats (3.47-fold increase, P < 0.01) as compared with SL rats, whereas at 30 wk, the plasma levels of insulin in PO and SO rats had decreased and there was no significant difference among the three groups. Hepatic triglycerides were increased (1.54-fold, P < 0.005) in PO rats, compared with SO rats. Hepatic acyl-CoA synthetase (ACS) activity was significantly augmented in PO rats at 30 wk (10%, P < 0.01 versus SO group), while microsomal triglyceride transfer protein (MTP) decreased (-27% versus SO, P < 0.05); thus, the increased ACS activity and decreased MTP might have a role in the accumulation of hepatic triglycerides in PO rats. In summary, pinealectomy causes severe hyperinsulinemia and accumulation of triglycerides in the liver, probably owing to the loss of the nocturnal melatonin surge.     

Insulin resistance in skeletal muscle of the male Otsuka Long-Evans Tokushima Fatty rat,a new model of NIDDM

Summary The Otsuka Long-Evans Tokushima Fatty rat is a new inbred obese strain with a late onset and chronic course of spontaneous hyperglycaemia in the male, and is considered to be a model of non-insulin-dependent diabetes mellitus [1, 2]. Fat distribution analysis showed a typical accumulation of intra-abdominal visceral fat in Otsuka Long-Evans Tokushima Fatty rats compared with a control strain, Long-Evans Tokushima Otsuka rats. To examine the insulin sensitivity of Otsuka Long-Evans Tokushima Fatty rats, we performed euglycaemic hyperinsulinaemic clamp experiments in vivo in rats under anaesthesia on this strain and on Long-Evans Tokushima Otsuka rats. The Otsuka Long-Evans Tokushima Fatty rats showed lower values for the glucose infusion rate (60% of the control at 12 weeks old and 20–30% of the control at 18, 24, 30 and 39 weeks old) than age-matched controls, indicating the development of insulin resistance with age. Hindlimb perfusion experiments in vitro also showed a 45% decrease of insulin-stimulated glucose uptake in Otsuka Long-Evans Tokushima Fatty rats in the diabetic stage. These results indicate that insulin resistance exists in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats. To obtain information on the mechanism of insulin resistance in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats, the insulin binding, autophosphorylation and tyrosine kinase activity of their partially-purified insulin receptors in vitro were compared with those from control rats. The results showed no marked differences in these insulin receptor functions between diabetic and control rats. These results suggest that it is unlikely that severe insulin-receptor dysfunction is responsible for the insulin resistance in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats.Abbreviations OLETF Otsuka Long-Evans Tokushima Fatty - LETO Long-Evans Tokushima Otsuka - ECL enhanced chemiluminescence - K_d dissociation constant - B_max maximal binding - BSA bovine serum albumin     

Role of early insulin secretion in postglucose-loading hyperglycaemia and postfat-loading hyperlipidaemia: comparing nateglinide and glibenclamide for acute effects on insulin secretion in OLETF rats

AIM: The aim of this study was to clarify the role of an early insulin secretion in postprandial hyperglycaemia and hyperlipidaemia; a study using spontaneously type 2 diabetic Otsuka Long-Evans Tokushima Fatty rats with visceral obesity was performed to investigate the acute effect of nateglinide (NAT) vs. glibenclamide (GB) on increases in glucose after glucose loading and on increases in triglyceride (TG) after fat loading. METHODS: Fasting rats were given 50 mg/kg of NAT, 1 mg/kg of GB or 5% methyl cellulose (vehicle) as control and then immediately given oral glucose 1 g/kg. RESULTS: An acute increase in insulin levels in portal blood peaked at 15 min in the NAT group, while insulin levels in the GB group continued to increase significantly after 60 min. Glucose levels in peripheral blood were significantly lower in the NAT group at 30 and 60 min and in the GB group at 120, 180 and 270 min after glucose loading, compared with those in the vehicle group. Subsequently, fasting rats were given NAT, GB or vehicle and then immediately given oral fat emulsion (soy oil 2 g/kg). An acute increase in insulin secretion was seen with NAT, peaking at 30 min, while TG, chylomicron and very low-density lipoprotein levels after fat loading were shown to be significantly lower with NAT than with vehicle. However, the continued insulin secretion observed with GB led to no significant decrease in TG levels after fat loading. In addition, lipoprotein lipase mRNA expression in adipose tissue increased significantly 120 min after NAT administration in comparison with baseline. This increase was not noted with GB administration. CONCLUSION: Abnormalities in early insulin secretion are closely associated with the pathogenesis of various disease conditions that combine to characterize type 2 diabetes, suggesting that normalizing early insulin response in portal blood represents an important treatment not only for postprandial hyperglycaemia but also for postprandial hyperlipidaemia.     

Alteration in haemodynamics and pathological changes in the cardiovascular system during the development of Type 2 diabetes mellitus in OLETF rats

Aims/hypothesis The process of cardiovascular complications in Type 2 diabetes mellitus (DM) is unclear. We investigated pathophysiological changes of the heart and vessels in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat Type 2 DM model during a long time period.Methods Echocardiography was carried out at 22 and 62 weeks of age of OLETF (n=10, each) and age-matched Long-Evans Tokushima Otsuka (LETO) rats (n=10, each) as a reference. Haemodynamic measurements and histological examinations of the heart and the coronary and aortic vascular walls were done.Results The left ventricular (LV) maximal -dP/dt was reduced in OLETF rats at 62 weeks (–1085±35 mmHg/s) less than that at 22 weeks (–1892±396 mmHg/sec, p<0.05) and in LETO rats at 62 weeks (–1306±200 mmHg/sec, p<0.05). Wall thickening of intramyocardial coronary arteries, capillary tortuosity and thickening of basement membrane were evident in OLETF rats at 62 weeks. Intimal and medial wall thickening of the aorta were prominent in OLETF rats at 62 weeks (15±2.2 and 90±6.6 µm, in LETO rats at 62 weeks, 2±0.4 and 65±5.2 µm, p <0.05, and in OLETF rats at 22 weeks, 7±4.6 and 71±6.0 µm, p<0.05, respectively).Conclusions/interpretation In the Type 2 DM model, angiopathy, especially in coronary arteries including small vessels, as well as a LV relaxation abnormality, are induced in a late stage of DM. These are considered to be important complications in Type 2 DM.Abbreviations OLETF Otsuka Long-Evans Tokushima Fatty - DM diabetes mellitus - LETO Long-Evans Tokushima Otsuka - STZ streptozotocin - 2-DE two-dimensional echocardiography - LVDd left ventricular end-diastolic diameter - LVDs left ventricular end-systolic diameter - IVST diastolic intraventricular septal wall thickness - LVPWT left ventricular posterior wall thickness - LVEF left ventricular ejection fraction - LV left ventricle - dP/dt first derivative of LV pressure     

减重治疗逆转超重及肥胖症患者脂肪肝的作用

目的：探讨超重及肥胖症患者合并脂肪肝的发病情况及其危险因素,减重治疗对肥胖症患者脂肪肝的逆转作用。方法：220例超重及肥胖症患者进行血生化、肝脏B超检查,其中45例肥胖症患者接受为期1年减重治疗,治疗前后测定体重,进行75g葡萄糖耐量试验,同时测定血真胰岛素水平,血生化及肝脏B超检查,评价减重治疗后脂肪肝转归的影响因素。结果：75.9％的超重及肥胖症患者有不同程度的脂肪肝,患者的体重指数、年龄、服糖后2h血糖水平、服糖后1h真胰岛素水平、腰围、低密度脂蛋白胆固醇水平是脂肪肝的危险因素。经过减重治疗,65.7％肥胖症患者的脂肪肝得到了改善,患者的血清转氨酶水平也有显著下降。结论：脂肪肝是肥胖症患者常见的并发症之 ,减轻体重是治疗肥胖症患者脂肪肝有效的治疗手段。     

Diazoxide prevents abdominal adiposity and fatty liver in obese OLETF rats at prediabetic stage

Epidemiological studies in both humans and experimental animals have shown an association between visceral obesity and cardiovascular risk factors such as dyslipidemia, hyperinsulinemia, and type 2 diabetes mellitus. The objective of this study was to evaluate the effects of diazoxide, an inhibitor of glucose-stimulated insulin secretion, on the prevention of fat deposition in the liver and in the abdominal cavity of prediabetic rats. Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which are a well-established animal model of human obesity, were used. Diazoxide (25 mg/kg/day) was administered from 8 to 30 weeks of age. Various fat distribution parameters, including computerized tomography imaging, histopathological examination, lipid metabolism, and insulin resistance, were determined in prediabetic OLETF rats. Occurrences of abdominal adiposity and fatty liver were markedly reduced by diazoxide treatment. Diazoxide significantly lowered hyperinsulinemia, triglycerides, free fatty acid levels, insulin resistance, weight gain, and food intake. In addition, it inhibited the development of diabetes in these animals. Linear regression assay demonstrated a close correlation between decreasing hyperinsulinemia and the protective effects of diazoxide. The present study demonstrates that diazoxide treatment in obese OLETF rats at prediabetic stage prevents abdominal obesity and fat deposition in the liver. These metabolic changes may occur through a direct effect on beta-cells through reduction of their workload and suppression of insulin secretion.     

Female spontaneously diabetic Torii fatty rats develop nonalcoholic steatohepatitis-like hepatic lesions

AIM: To investigate the histological features of the liver in spontaneously diabetic Torii (SDT) fatty rats compared with age-matched Sprague-Dawley (SD) rats.METHODS: Female SDT Lepr^fa (SDT fatty) rats and age-matched SD rats were fed ad libitum. Body weight and biochemical parameters, such as serum glucose, triglyceride (TG), total cholesterol (TC), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels as well as fatty acid and TG accumulation in the liver were evaluated at 8 wk of age in the non-fasting state and at 8-wk intervals from 8 to 40 wk of age. Histopathological examinations of the liver were performed using hematoxylin and eosin and Sirius Red staining as well as double staining for ED-1 and toluidine blue. The expression of genes involved in TG synthesis, inflammation, and fibrosis was examined in the liver.RESULTS: SDT fatty rats showed significantly increased body weight compared with SD rats. Serum glucose, TG, and TC levels were significantly higher in SDT fatty rats compared with SD rats. The serum AST and ALT levels in SDT fatty rats were significantly elevated at 8 wk of age compared with the levels in SD rats. Hepatic TG content was marked in SDT fatty rats from 8 to 32 wk of age. Histopathologically, severe hepatosteatosis accompanied by inflammation was observed at 8 wk of age, and fibrosis started to occur at 32 wk of age. Furthermore, Sirius Red and ED-1 staining were increased in the liver at 32 wk of age. Hepatic gene expression related to TG synthesis, inflammation and fibrosis tended to increase in SDT fatty rats compared with SD rats, and the gene expression related to TG secretion was decreased in SDT fatty rats compared with SD rats.CONCLUSION: Female SDT fatty rats have the potential to become an important animal model of nonalcoholic steatohepatitis with type 2 diabetes and obesity.     

脂肪酸结合蛋白在防治脂肪肝中的作用

脂肪酸结合蛋白（FABPs）是细胞内运输长链脂肪酸的蛋白超级家族成员,到目前为止发现有9种不同的FABPs。作为脂肪酸的转运体,其功能已经有大量研究证实。最近几年,许多试验更直接证实了FABPs的转运脂肪酸、参与细胞内脂质代谢作用。深入研究FABPs,在脂肪肝的检测、防治中具有重要意义。     

Troglitazone reduces plasma levels of tumour necrosis factor-alpha in obese patients with type 2 diabetes

We evaluated the effect of troglitazone (given orally 400 mg/day) on glucose intolerance and on the plasma levels of tumour necrosis factor-alpha (TNF-alpha) in 12 obese patients with type 2 diabetes for 12 weeks. Troglitazone significantly decreased fasting plasma glucose, serum C-peptide, serum insulin and HbA1c levels. Plasma levels of TNF-alpha were significantly reduced by troglitazone administered for 8 and 12 weeks. Troglitazone administration significantly improved insulin resistance, but did not affect pancreatic beta-cell function as evaluated by the homeostasis model assessment (HOMA). In the present study, we reported for the first time that troglitazone administration significantly reduces plasma levels of TNF-alpha in obese patients with type 2 diabetes.     

酒精性脂肪肝大鼠肝组织骨桥蛋白表达的变化

目的探讨乙醇联合高脂饮食诱导脂肪肝大鼠肝组织骨桥蛋白（OPN）表达的变化。方法采用高脂饮食联合乙醇灌胃制备大鼠脂肪肝模型。在第6周末分别取血和肝组织,常规检测血生化指标和采用Westernblot法检测大鼠肝组织骨桥蛋白表达的改变。结果乙醇联合高脂饮食条件下大鼠血清ALT、AST、TG、TC水平升高（P〈0．05）,HDL-C降低（P〈0．05）;油红O染色结果显示乙醇联合高脂饮食组大鼠肝脏脂肪变明显;模型组大鼠肝组织OPN蛋白表达明显增强（P〈0．05）。结论骨桥蛋白表达增强在大鼠乙醇性脂肪肝的发病过程中起一定的作用。     

2型糖尿病合并脂肪肝大鼠肝脏基因表达谱

用基因芯片比较2型糖尿病合并脂肪肝大鼠和正常大鼠肝脏组织基因表达差异，共筛选出223个差异表达基因，初步探讨2型糖尿病合并脂肪肝与胰岛素抵抗之间的关系。     

高脂血症性脂肪肝大鼠血清游离脂肪酸的变化及意义

为探讨血清游离脂肪酸各组分在高脂血症性脂肪肝形成过程中的变化,并为其治疗方案提供依据.通过高脂食饵性饲养建立高脂血症性脂肪肝大鼠模型,测定其血清游离脂肪酸(FFA)组分,并与对照组进行比较.结果显示,与对照组相比,高脂血症性脂肪肝模型FFA各组分中棕榈酸(C16∶0)、亚油酸(C18∶2)增高(P均<0.05),肉豆蔻酸(C14∶0)明显增高(P<0.01),而硬脂酸(C18∶0)、花生四烯酸(C20∶4)则显著降低(P均<0.01),月桂酸(C12∶0)、油酸(C18∶1)变化不明显.提示高脂血症脂肪肝血FFA组分有特征性改变,C18∶2可能无防治脂肪肝的作用.     

Troglitazone prevents the rise in visceral adiposity and improves fatty liver associated with sulfonylurea therapy--a randomized controlled trial

Monotherapy with sulfonylurea may result in the exhaustion of pancreatic beta-cell function, fat accumulation, and dyslipidemia. We examined the possibility of dose reduction by administering sulfonylurea together with troglitazone, and investigated changes in insulin secretion and fat deposition. Seventy-eight patients with type 2 diabetes adequately controlled with glibenclamide were randomly allocated to a troglitazone (400 mg/d)-added group (n = 40) or a control group without placebo (n = 38) and monitored for 24 weeks. The daily dose of glibenclamide was adjusted to maintain stable HbA(1c) levels. Fat accumulation to the liver and thigh muscle were measured in mean Hounsfield units determined on computed tomography (CT) scan. Visceral fat accumulation (V), subcutaneous fat accumulation (S), and the V/S ratio were also determined by CT scan. The daily dose of glibenclamide and serum fasting insulin level in the troglitazone-added group significantly decreased (from 4.05 +/- 2.50 mg/d to 1.84 +/- 1.65 mg/d and from 8.47 +/- 4.62 microU/mL to 6.49 +/- 3.28 microU/mL, respectively) during the observation period compared with the control group (P < .01 and P < .01, respectively). Serum triglyceride and homeostasis model insulin resistance index (HOMA-R) in the troglitazone-added group decreased significantly in comparison to the control group (P < .05 and P < .01, respectively). The mean Hounsfield units of liver significantly decreased in the control group compared with the troglitazone-added group (P < .05). Visceral fat area and the V/S ratio significantly increased in the control group compared with the troglitazone-added group (P < .01 and P < .01, respectively). Glibenclamide monotherapy resulted in fat accumulation accompanied by dyslipidemia. An alternate conclusion is that troglitazone reversed type 2 diabetes (not sulfonylurea)-associated fat accumulation. The addition of troglitazone decreased daily doses of glibenclamide, preserved fasting insulin secretion, improved fat accumulation in liver, and prevented dyslipidemia.     

胰岛素治疗逆转糖尿病小鼠肝脏的脂肪沉积

观察胰岛素治疗对糖尿病小鼠脂肪肝的影响.C57BL/6J小鼠高脂饲养12周后,甘精胰岛素皮下注射4周.结果 显示,与高脂组相比,胰岛素组腹腔葡萄糖耐量试验所有时间点血糖及血总胆同醇、甘油三酯(TG)均显著改善(P相似文献   

肥胖儿童血清脂联素水平与非酒精性脂肪性肝病的关系

非酒精性脂肪性肝病（NAFLD）是一种临床病理综合征，它的范畴从单纯的脂肪变性到非酒精性脂肪性肝炎、纤维化和终末期肝病。被认为是导致儿童肝脏疾病的最主要病因，并且与全球范围内的儿童肥胖发生率上升呈平行状态。由于目前尚无特异的治疗方案，其机制的研究对于阻止NAFLD的发生有重要意义。最近的研究结果表明，胰岛素抵抗和氧化应激可能参与了其病理生理过程。脂联索是近来发现的脂肪组织分泌产物，是由脂肪细胞分泌并存在于血液循环中，是脂肪组织产生最多的基因产物。与其他所知的脂肪细胞因子不同，2型糖尿病和冠心病患者脂联素水平低下。最近在肥胖患者，甚至肥胖患儿中也发现了相对较低的血清脂联素水平，     

普罗布考对大鼠非酒精性脂肪性肝病的预防及机制研究

目的 观察普罗布考对大鼠非酒精性脂肪性肝病（NAFLD）的预防作用．并探讨其可能作用机理。方法 24只雄性sD大鼠随机分3组：正常对照组、NAFLD对照组、普罗布考干预组。以高脂饲料饲养诱发脂肪肝大鼠模型。18周末，处死所有动物，检测血脂、肝功能、肝脂质含量、氧化还原指标、肝组织病理学等。结果与NAFLD对照组比较，普罗布考干预组TC（2．98±0．90）mmol／L vs（4．45±1．15）mmol／L，ALT（78．25±18．47）U／L vs（110．2±36．33）U／L及肝组织TG含量（2．61±0．20）mmol／L vs（2．93±0．36）mmol／L均显著下降（P均〈0．05），其肝脂肪变性及炎症程度亦显著减轻（P均〈0．05）。结论 普罗布考可对高脂饲料饲养诱发的大鼠NAFLD产生保护作用；其保护作用与提高机体抗氧化能力．减轻组织氧化应激损害有关。