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OLETF Rats (oletf + rat)

Distribution by Scientific Domains

Medical Sciences	58%
Life Sciences	16%

Selected Abstracts

Hyperphagia and obesity of OLETF rats lacking CCK1 receptors: Developmental aspects

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 5 2006
Timothy H. Moran
Abstract Otsuka Long Evans Tokushima Fatty (OLETF) rats have a deletion in the gene encoding the cholecystokinin,1 (CCK1) receptor. This deletion prevents protein expression, making the OLETF rat a CCK1 receptor knockout model. Consistent with the absence of CCK1 receptors, OLETF rats do not reduce their food intake in response to exogenously administered CCK and consume larger than normal meals. This deficit in within-meal feedback signaling is evident in liquid as well as solid meals. Neonatal OLETF rats show similar differences in independent ingestion tests. Intake is higher and is reflected in greater licking behavior. Neonatal OLETF rats also have diminished latencies to consume and higher initial ingestion rats. Adult OLETF rats are hyperphagic and obese. Although arcuate nucleus peptide gene expression is apparently normal in OLETF rats, when obesity is prevented through pair-feeding to amounts consumed by control Long Evans Tokushima Otsuka (LETO) rats, dorsomedial hypothalamic NPY mRNA expression is significantly elevated in OLETF rats. NPY overexpression is also evident in preobese, juvenile OLETF rats suggesting a causal role for this overexpression in the hyperphagia and obesity. Running wheel exercise normalizes food intake and body weight in OLETF rats. When access to exercise is provided at a time when OLETF rats are obese, the effects are limited to the period of exercise. When running wheel access is available to younger, preobese OLETF rats, exercise results in long lasting reductions in food intake and body weight and improved glucose regulation. These lasting metabolic effects of exercise may be secondary to an exercise induced reduction in DMH NPY mRNA expression. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 360,367, 2006. [source]

A quantitative study of the optic nerve in diabetic mutant, Otsuka Long-Evans Tokushima Fatty (OLETF) rats

CONGENITAL ANOMALIES, Issue 4 2001
Kazuhiko Sawada
ABSTRACT, Optic nerves of the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of non-insulin dependent diabetes mellitus, were examined using quantitative stereological procedures. At 67 weeks of age, OLETF rats showed a mild hyperglycemia: their blood glucose level was 196 ± 93 mg/dl, significantly higher than that of non-diabetic control Long-Evans Tokushima Otsuka (LETO) rats (110 ± 24 mg/dl). However, there were no differences in the cross sectional area of optic nerves (the mean minimum diameter), the total number and mean diameter of both myelinated and non-myelinated fibers, or the thickness of the myelin sheath between OLETF and LETO rats. The results suggested that a mild hyperglycemia in OLETF rats could not cause any morphological changes in the optic nerve. [source]

Hyperphagia and obesity of OLETF rats lacking CCK1 receptors: Developmental aspects

The different mechanisms of insulin sensitizers to prevent type 2 diabetes in OLETF rats

DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 5 2007
Sung Hee Choi
Abstract Objective To investigate the effects of pioglitazone and metformin treatment during pre-diabetic period for the prevention of diabetes in a rat model. Methods OLETF rats aged 18-weeks, were treated with pioglitazone (10 mg/kg/day) and metformin (300 mg/kg/day) for 10 weeks from their pre-diabetic period. We measured weight, lipid profiles, fat distribution, glucose tolerance, and pancreatic insulin content. Results Prominent weight gain (mostly subcutaneous fat area) was observed in the pioglitazone-treated OLETF (O-P) rats versus significant weight loss was observed in the metformin-treated OLETF (O-M) rats. Pioglitazone reversed the serum triglyceride (TG) and FFAs levels to normal (TG 0.46 ± 0.04 vs 0.88 ± 0.05 mmol/l in LETO). At the age of 28 weeks, the O-P rats showed completely normal glucose tolerance, and the glucose disposal rate (GDR) was markedly improved (25.6 ± 0.4 vs 20.6 ± 0.5 mg/min/kg in O-C, p < 0.05). The O-M rats also showed an improved fasting glucose and GDR level, but not as much as those with O-P rats. The pancreas insulin contents were much improved in the O-P rats (22.9 ± 1.2 vs 18.8 ± 1.3 nmol/pancreas in O-M rats, p < 0.05) with histological improvement. Conclusion The pre-diabetic treatment with pioglitazone, despite significant weight gain, completely prevents to develop diabetes and enhances beta cell function with preservation of islet cell changes. Metformin treatment was also effective, but mainly by ameliorating the insulin resistance with marked reduction in body weight. The reversal of dyslipidaemia and the fat redistribution might contribute to the greater improvement of pioglitazone treatment compared to metformin in OLETF rats. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Troglitazone prevents fatty changes of the liver in obese diabetic rats

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 10 2000
Dong Mei Jia
Abstract Background and Aims: Troglitazone is a newly developed antidiabetic drug and is indicated to be useful for the treatment of patients with type II diabetes mellitus. Recently, however, it became clear that troglitazone could cause liver dysfunction in some patients. In addition, a relationship between the activation of the peroxisome proliferator-activated receptor gamma receptor by troglitazone and colon tumorigenesis has been suggested. The present study was undertaken to examine the effects of long-term administration of troglitazone on the liver and intestine in genetically obese and diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) and control Long-Evans Tokushima Otsuka (LETO) rats. Methods: A troglitazone-rich diet (200 mg/100 g normal chow) or a standard rat chow, free of troglitazone (control), was given to OLETF and LETO rats from 12 or 28 weeks of age until 72 weeks of age. Serum levels of glucose, insulin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were determined at several time points. In addition, histology of the liver and intestine and serum levels of cholesterol and triglycerides were examined at 72 weeks of age. Results: Troglitazone prevented age-related increases in fasting glucose and insulin concentrations in OLETF rats, but had no significant influences on serum levels of AST and ALT in both strains of rats. The liver weights in the control OLETF rats were significantly heavier than in the LETO rats. Troglitazone significantly reduced serum cholesterol and triglyceride levels and the liver weight. However, it had no influence on the large intestine weight and the number of colonic polyps in both OLETF and LETO rats. Sections of the liver from the untreated OLETF rats showed mild fatty changes in the central zone of the hepatic lobule, whereas those from the troglitazone-treated OLETF rats appeared normal with no fat deposition in the hepatocytes. Troglitazone in LETO rats also caused no significant histopathologic changes of the liver tissue. Conclusion: Our present study demonstrated that long-term administration of troglitazone prevents the progress of the metabolic derangement and fatty changes of the liver in genetically determined obese diabetes. [source]

Activity of the Chinese prescription Hachimi-jio-gan against renal damage in the Otsuka Long-Evans Tokushima Fatty rat: a model of human type 2 diabetes mellitus

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2006
Noriko Yamabe
Currently, in Japan, approximately 95% of patients with diabetes mellitus have non-insulin-dependent (type 2) diabetes mellitus (NIDDM), and diabetic nephropathy is a major cause of patients requiring chronic haemodialysis. A previous study showed that Hachimi-jio-gan has a protective effect in rats subjected to subtotal nephrectomy plus streptozotocin injection, a model of insulin-dependent (type 1) diabetic nephropathy. In this study, we used the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of human NIDDM, to investigate whether long-term administration of Hachimi-jio-gan affects glycaemic control and renal function in NIDDM. Male OLETF rats, aged 22 weeks, were divided into 4 groups of 10 and given Hachimi-jio-gan (50, 100 or 200 mg kg,1 daily) orally or no treatment for 32 weeks. Male Long-Evans Tokushima Otsuka (LETO) rats (n = 6) were used as non-diabetic normal controls. Hachimi-jio-gan reduced hyperglycaemia dose-dependently from 16 weeks of the administration period. Urinary protein excretion decreased significantly from an early stage, and creatinine clearance levels improved at 32 weeks. In addition, the levels of serum glycosylated protein and renal advanced glycation end-products were effectively reduced. Hachimi-jio-gan also significantly reduced the levels of thiobarbituric acid-reactive substances in renal mitochondria, although it showed only a tendency to reduce these in serum. Furthermore, long-term administration of Hachimi-jio-gan reduced renal cortical expression of proteins, such as transforming growth factor-,1 (TGF-,1), fibronectin, inducible nitric oxide synthase and cyclooxygenase-2. The 100- and 200-mg kg,1 daily doses of Hachimi-jio-gan significantly reduced TGF-,1 and fibronectin protein expression to levels below those of LETO rats. These data suggest that Hachimi-jio-gan may have a beneficial effect on the progression of diabetic nephropathy in OLETF rats by attenuating glucose toxicity and renal damage. [source]

Genetic analysis of pancreatic duct hyperplasia in Otsuka Long,Evans Tokushima Fatty rats: Possible association with a region on rat chromosome 14 that includes the disrupted cholecystokinin-A receptor gene

PATHOLOGY INTERNATIONAL, Issue 3 2001
Naohide Kanemoto
An Otsuka Long,Evans Tokushima Fatty (OLETF) strain of rat spontaneously developed hyperglycemia, hyperinsulinemia, insulin resistance and mild obesity, which had been studied as animal model for type II diabetes mellitus (T2DM). Recently, we observed that this strain coincidentally developed atypical hyperplasia of the choledocho-pancreatic ductal epithelium with a complete incidence. In an effort to locate genes responsible for this hyperplasia, we prepared 288 backcross progeny from a mating between OLETF rats and BN rats (which do not develop hyperplasia), and performed a genome-wide scan using 207 polymorphic genetic markers. We observed a prominent association of hyperplasia with a region involving a marker locus D14Mit4 (P = 0.00020, Fisher's exact test) and Cckar (the cholecystokinin-A receptor gene; P = 0.00025, Fisher's exact test) which is known to be disrupted in an OLETF strain. Our findings indicated that epithelial hyperplasia of the choledocho-pancreatic duct is associated with a region on rat chromosome 14 around the Cckar gene in an additive fashion with another two susceptible loci, each on chromosome 9 and 7. This implied the possibility that Cckar deficiency could result in a predisposition towards pancreatic duct hyperplasia. [source]

Effect of AOB, a fermented-grain food supplement, on oxidative stress in type 2 diabetic rats

BIOFACTORS, Issue 2 2007
Yukiko Minamiyama
Abstract Reactive oxygen species (ROS) play an important role in the pathogenesis of diabetic complications. Antioxidant Biofactor (AOB) is a mixture of commercially available fermented grain foods and has strong antioxidant activity. This study investigated the effect of AOB supplementation of standard rat food on markers of oxidative stress and inflammation in Otsuka Long-Evans Tokushima Fatty (OLETF) rats with type 2 diabetes. Blood glucose, hemoglobin A1c, plasma free fatty acid, triacylglycerol and plasminogen activator inhibitor-1 (PAI-1) were significantly higher in OLETF rats than in non-diabetic control Long-Evans Tokushima Otsuka (LETO) rats at 29 weeks. AOB (6.5% of diet) was given to rats during 29,33 weeks of diabetic phase in OLETF rats. OLETF rats with AOB supplementation showed decreased blood glucose, hemoglobin A1c, triacylgycerol, low density lipoprotein, cholesterol and PAI-1. Mitochondrial ROS production was significantly increased in heart, aorta, liver and renal artery of OLETF rats. Uncoupling protein 2 (UCP2) is known to regulate ROS production. We found aortic UCP2 protein expression increased in OLETF rats, and AOB returned UCP2 expression to normal. Aortic endothelial NO synthase (eNOS) was also increased in OLETF rats more than in LETO rats at 33 weeks. In contrast, phosphorylated vasodilator-stimulated phosphoprotein, an index of the NO-cGMP pathway, was significantly diminished. AOB increased eNOS proteins in LETO and OLETF rats. In conclusion, AOB significantly improved the NO-cGMP pathway via normalizing ROS generation in OLETF rats. The data suggest that dietary supplementation with AOB contributes to nutritional strategies for the prevention and treatment of type 2 diabetes mellitus. [source]