Genetic dissection of "OLETF," a rat model for non-insulin-dependent diabetes mellitus: quantitative trait locus analysis of (OLETF x BN) x OLETF.

To identify genetic determinants relevant to non-insulin-dependent diabetes mellitus (NIDDM), we performed a genome-wide analysis for quantitative trait loci (QTLs) using 359 backcross progeny of the Otsuka Long-Evans Tokushima Fatty (OLETF) rat. The OLETF strain is a well-studied animal model of obese NIDDM, with features of hyperinsulinemia, hyperglycemia, insulin resistance, and abundant abdominal fat. Our extensive genomic scanning with 218 markers revealed nine significant QTLs, including a strong determinant of obesity on chromosome 1 (Dmo1: LOD = 13.99, for body weight). Two highly significant QTLs for glucose homeostasis were found, one on chromosome 1 (Dmo4 LOD = 7.16, for postprandial glucose level) and the other on chromosome X (Dmo11/Odb1: LOD = 7.81, for postprandial glucose level). These data are comparable to results of our previous studies of the OLETF rat.     

The BHE rat: an animal model for the study of non-insulin-dependent diabetes mellitus

Most rodents that spontaneously develop non-insulin-dependent diabetes mellitus are obese. The exception is the BHE rat. This rat develops abnormal glucose tolerance by 300 days of age, is lipemic, has a fatty liver, and yet is not obese. The strain has existed for at least 40 years and almost 100 research papers have been published describing its metabolic characteristics and responses to diet manipulation. A subline that has a higher percentage of diabetic animals has been produced. These animals may be useful in the study of mild diabetes that exists in the absence of obesity. Berdanier, C.D. The BHE rat: an animal model for the study of non-insulin-dependent diabetes mellitus.     

Genetic analysis for diabetes in a new rat model of nonobese type 2 diabetes,Spontaneously Diabetic Torii rat

The Spontaneously Diabetic Torii (SDT) rat has recently been established as a new rat model of nonobese type 2 diabetes. In this study, we characterized diabetic features in SDT rats, and performed quantitative trait locus (QTL) analysis for glucose intolerance using 319 male (BNxSDT)xSDT backcrosses. Male SDT rats exhibited glucose intolerance at 20 weeks, and spontaneously developed diabetes with the incidence of 100% at 38 weeks, and glucose intolerance is well associated with the development of diabetes. The QTL analysis identified three highly significant QTLs (Gisdt1, Gisdt2, and Gisdt3) for glucose intolerance on rat chromosomes 1, 2, and X, respectively. The SDT allele for these QTLs significantly exacerbated glucose intolerance. Furthermore, synergistic interactions among these QTLs were detected. These findings indicate that diabetic features in SDT rats are inherited as polygenic traits and that SDT rats would provide insights into genetics of human type 2 diabetes.     

Early-life background and the development of non-insulin-dependent diabetes mellitus

The relationship of early-life background factors to type 2, or non-insulin-dependent, diabetes mellitus (NIDDM) was examined with reference to family history of diabetes in two groups of Nisei (U.S. born/raised Japanese American) men from King County, Washington with identical mean (+/- S.E.M.) ages: 78 with NIDDM, 61.6 (+/- 0.7) years of age; and 79 with normal glucose tolerance (NGT), 61.6 (+/- 0.6) years of age. The early-life variables were birthplace, parents' education, father's occupation and mother's employment status during subject's childhood, sibship size, son birth order, physical activity and weight assessed for ages 15-20 years, and educational achievement. Multivariate logistic regression models were used to test for the effect of each variable on the risk for diabetes in the presence of other variables. Results are presented as odds ratios (OR) with 95% confidence intervals (CI). Significantly higher risk for NIDDM was found with urban birthplace (vs. rural, OR = 2.09, 95% CI = 1.37-3.19), parents' education above primary level (vs. primary level or less, OR = 1.64, 95% CI = 1.08-2.50), mother being employed (vs. housewife, OR = 2.17, 95% CI = 1.43-3.45), subject being less active-lean as a youth (vs. more active-lean, OR = 1.69, 95% CI = 1.11-2.63), and subject's not attaining a college degree (vs. college degree, OR = 2.17, 95% CI = 1.41-3.33). In separate analyses of the early-life variables by family history of diabetes, the interplay of environmental influences with familial predisposition to NIDDM is evident. The developmental background of NIDDM is discussed with reference to the concept of phenotype amplification within the context of the effects of westernization.     

Insulin replacement therapy for the rat model of streptozotocin-induced diabetes mellitus

OBJECTIVE: This study was conducted to compare various strategies for insulin replacement therapy in the streptozotocin-induced diabetic rat model. METHODS: Control and diabetic Sprague Dawley rats were fed ad libitum, blood glucose concentration was measured twice daily, and outcome was assessed over the final 5 days of a 10-day treatment period, with adjustment of insulin dosage toward the goal of normal glucose values. RESULTS: All insulin regimens induced weight gain at least comparable to that of controls, but glucose regulation differed. It was not possible to normalize glucose values by use of protamine zinc insulin (PZI) or Ultralente insulin given once daily. In contrast, PZI and neutral protamine Hagedorn (NPH) insulin given twice daily provided glucose values comparable to those in controls, whereas glucose values were modestly higher in response to a 70% human insulin isophane suspension and 30% soluble human insulin solution (70/ 30 insulin) given twice daily. Attempted normalization of glucose values was limited by hypoglycemia, which was most common after administration of PZI once daily, and least common after 70/30 insulin given twice daily. Dosage requirements for Ultralente insulin were four- to fivefold higher than those for all other insulins. CONCLUSION: In streptozotocin-diabetic rats, normal weight gain can be achieved by treatment with PZI insulin once daily, but attainment of near-normal glucose values requires administration of PZI, NPH, or 70/ 30 insulin twice daily. Ultralente insulin may have reduced bioeffectiveness in this animal model.     

Coagulation inhibitors and glycaemic control in non-insulin-dependent diabetes mellitus

The relationship between long-term glycaemic control and the activity of coagulation inhibitors was investigated in 60 non-insulin-dependent diabetes mellitus (NIDDM) patients not on insulin therapy. Overall, the activities of antithrombin III (AT III) (median 96%, range 65–133%), protein C (127%, 24–190%) and protein S (130%, 54–163%) were not reduced. Patients in poor long-term glycaemic control as verified by increased glycated haemoglobin (HbA1c) demonstrated significantly decreased median AT III activity in comparison with patients in good glycaemic control (92% vs 101%,P=0.016). However, individual values for AT III activity were not below the critical limit of 60%. An inverse correlation between AT III activity and long-term glycaemic control (HbA1c) was calculated (r=–0.378,P=0.0029). As AT III concentrations were found to be normal, we propose that non-enzymatic glycation leads to reduced activity of AT III without affecting its concentration.     

Apolipoprotein A-I gene polymorphism and susceptibility of non-insulin-dependent diabetes mellitus

A polymorphic DNA sequence of the apolipoprotein (apo) A-I gene region was studied in relation to non-insulin-dependent diabetes mellitus (NIDDM). We have examined 100 patients with NIDDM and 100 control subjects as well. The presence of a unique 2.5-kilobase (kb) EcoRI fragment was found in 13 diabetic patients and two control subjects with family history of diabetes. There were six homozygotes and nine heterozygotes among them. The analysis of clinical data did not confirm any linkage between the presence of a 2.5-kb fragment and atherosclerosis. These findings suggest that the observed defect in the apo A-I gene region may confer susceptibility to NIDDM.     

Genetic analysis of the LEW.1AR1-iddm rat: an animal model for spontaneous diabetes mellitus

The LEW.1AR1-iddm/Ztm rat is a new animal model of type 1 diabetes mellitus, which shows an autosomal recessive mode of inheritance for the diabetes-inducing gene. The aim of this study was to define predisposing loci of the diabetic syndrome by linkage analysis using microsatellite markers. A backcross population of 218 rats (BN × LEW.1AR1-iddm) × LEW.1AR1-iddm was analyzed using 157 polymorphic microsatellite markers covering the entire genome. Three genomic regions showed a significant linkage to the diabetic syndrome. The first susceptibility locus on rat Chromosome (RNO) 1 (LOD score 4.13) mapped to the region 1q51–55, which codes for potential candidate genes like Ins1 and Nkx2-3. The second susceptibility locus was also localized on RNO1 in the centromeric region 1p11 (LOD score 2.7) encompassing the Sod2 gene. The third quantitative trait loci (LOD score 2.97) was located on RNO20 within the major histocompatibility complex region. Comparative mapping revealed that the homologous regions in the human genome contain the IDDM loci 1, 5, 8, and 17. The identification of diabetes susceptibility regions of the genetically uniform LEW.1AR1-iddm rat strain will pave the way toward a detailed characterization of the loci conferring diabetes development as well as their functional relevance for the pathogenesis of type 1 diabetes mellitus.     

Hypoglycemic and hypolipidemic effects of processed Aloe vera gel in a mouse model of non-insulin-dependent diabetes mellitus

The effects of processed Aloe vera gel (PAG) on the course of established diet-induced non-insulin-dependent diabetes mellitus (NIDDM) were studied in C57BL/6J mice. NIDDM was induced in C57BL/6J mice by feeding them a high-fat diet. Mice exhibiting diet-induced obesity (DIO) with blood glucose levels above 180 mg/dl were selected to examine the antidiabetic effects of PAG. Oral administration of PAG for 8 weeks reduced circulating blood glucose concentrations to a normal level in these DIO mice. In addition, the administration of PAG significantly decreased plasma insulin. The antidiabetic effects of PAG were also confirmed by intraperitoneal glucose tolerance testing. PAG appeared to lower blood glucose levels by decreasing insulin resistance. The administration of PAG also lowered triacylglyceride levels in liver and plasma. Histological examinations of periepididymal fat pad showed that PAG reduced the average size of adipocytes. These results demonstrate that the oral administration of PAG prevents the progression of NIDDM-related symptoms in high-fat diet-fed mice, and suggest that PAG could be useful for treating NIDDM.     

Heterogeneity of non-insulin-dependent diabetes mellitus in HLA types and clinical features: comparison with insulin-dependent diabetes mellitus

We determined HLA types in 110 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) and studied the relationship between the HLA phenotypes and clinical features. Sixty-nine patients with insulin-dependent diabetes mellitus (IDDM) and 100 healthy blood donors served as controls. Concerning HLA DR and DQ loci, frequencies of DR4, DRw9 and DQw3.2 were higher, and those of DR2, DRw8, DRw11, DRw12 and DQw1 were lower in patients with IDDM compared than in healthy controls. There were no differences between NIDDM and normal controls in the frequency of a particular HLA DR antigen except for a decreased frequency in DRw11 in the former. The frequency of DQw3.2 antigen in NIDDM was intermediate between IDDM and normal controls. There were some differences between DQw3.2-positive and -negative NIDDM patients in clinical features. Those who showed low C-peptide responses during oral glucose tolerance test were more frequently found among DQw3.2-positive NIDDM patients. These results suggest that Type 1 diabetes mellitus may have a mild clinical course and is found among the Japanese NIDDM population.     

Segregation analysis of non-insulin-dependent diabetes mellitus in Pima Indians: evidence for a major-gene effect.

Non-insulin-dependent diabetes mellitus (NIDDM) has a high prevalence in Pima Indians. The disorder is familial, but the extent to which genetic factors are involved in its etiology is largely unknown. Segregation analysis was used to determine whether familial aggregation of NIDDM in this population could reflect the action of a single major gene. The analysis included 2,697 subjects from 653 nuclear families in which both parents and at least one offspring had been examined in the course of a longitudinal epidemiological study. The REGTL program of the SAGE package was used to fit models in which age at onset of NIDDM is transmitted from parent to offspring under the unified model for segregation analysis. Likelihood-ratio tests were used to test hypotheses related to genetic transmission. The hypothesis of no major effect was strongly rejected (P < .01), as was that of no transmission of the major effect (P < .01). Mendelian transmission was not rejected (P = .91). Similar results were obtained when covariates for obesity and birth cohort were added to the models and when a power transformation of age at onset was estimated. A strong effect of birth cohort with earlier age at onset in the later born cohorts was observed (P < .01). The findings are consistent with the hypothesis that a major gene influences the risk for NIDDM in Pima Indians by affecting age at onset. The expression of this gene may depend on environmental factors that have become more prevalent in recent-birth cohorts.     

Genetic epidemiology of non-insulin-dependent diabetes mellitus in north India: preliminary analyses of some genetic markers in Punjabis

Studies on monozygotic (MZ) twins and admixed populations show that the predisposition to non-insulin-dependent diabetes mellitus has a large genetic component. We have examined the distribution of some genetic polymorphisms (ABO, GLO, ESD, AK, ACPA, and GPI) in control and diabetic Punjabis from north India. The distribution of various genetic markers indicate that the differences between the control and diabetic samples are statistically not significant. Moreover, a contingency chi-square analysis over all loci suggests nonsignificant genetic differentiation (p = 0.50) between the Punjabi samples.     

Human sciatic nerve phospholipid profiles from non-diabetes mellitus,non-insulin-dependent diabetes mellitus and insulin-dependent diabetes mellitus individuals. A 31P NMR spectroscopy study

• 1.1. Human sciatic nerve phospholipids obtained from non-diabetes mellitus (NDM), non-insulin-dependent diabetes mellitus (NIDDM), and insulin-dependent diabetes mellitus (IDDM) patients, after lower extremity amputation, were studied by ³¹P NMR spectrometry.
• 2.2. Nine phospholipids resonances in NDM and NIDDM groups were identified as followed: Ethanolamine plasmalogen (Epias, Chemical shift = 0.07δ); phosphatidylethanolamine (PE, 0.03δ); phosphatidylserine (PS, −0.05δ); sphingomyelin (SM, −0.09δ); lysophosphatidylcholine (LPC, −0.28δ); phosphatidylinositol (PI, −0.30δ); alkylacylphosphorylcholine (A1.PC, -0.78δ); phosphatidylcholine (PC −0.84δ), and an unknown resonance (U, 0.13δ).
• 3.3. In the IDDM group a resonance of lysophosphatidylinositol (LPI, 0.01δ) was detected in addition to the nine phospholipids listed above.
• 4.4. IDDM showed that PI and Al.PC were elevated and U was lower when compared with NDM; also, Eplas was lower when compared with NIDDM. PC was elevated and PS was lower when compared with both NDM and NIDDM.
• 5.5. Indices calculated from this data, showed that the choline ratio and choline/ ethanolamine ratio were elevated; while ethanolamine ratio, and myelin ratio were lower in IDDM group, when compared with both NDM and NIDDM groups.
• 6.6. Inactivation of the cholineacethyltransferase enzyme (ChAT) and enhancement of the phospholipidmethyltransferase enzyme (PLMT), secondary to an insulin deficiency, are proposed as an interpretation of these findings.

     

Identification of epistatic interactions involved in non-insulin-dependent diabetes mellitus in the Otsuka Long-Evans Tokushima Fatty rat.

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type non-insulin-dependent diabetes mellitus (NIDDM) in humans. Our present investigation was designed to identify epistatic interactions influencing NIDDM by performing least squares analysis of variance of all pairs of informative markers in 160 F2 progenies bred from an intercross of OLETF and Fischer-344 rats. We identified four interactions between Nidd15/of (chromosome 7) and Nidd16/of (chromosome 14), Nidd15/of and Nidd17/of (chromosome 15), Nidd16/of and Nidd18/of (chromosome 15), and Nidd16/of and Nidd19/of (chromosome 17), which account for a total of approximately 40% of the genetic variation of entire glucose levels after glucose challenge in the F2. The Nidd16/of locus, which is involved in three of four digenic interactions, and the Nidd19/of are likely to correspond to Nidd2/of and Nidd14/of, NIDDM loci previously identified in the F2 by single-QTL model and multiple-QTL model, respectively, while Nidd15/of, Nidd17/of and Nidd18/of loci reflect novel NIDDM loci. An aberrant increase of the entire glucose level due to synergism occurs in the double OLETF homozygote genotype of Nidd15/of and Nidd16/of, and of Nidd16/of and Nidd19/of, as well as in the OLETF homozygote genotypes of Nidd15/of and Nidd16/of, respectively, combined with the heterozygote genotypes of Nidd17/of and Nidd18/of. These findings demonstrate that inter-allelic interactions are likely to be an important component of NIDDM susceptibility.     

Functional levels of mitochondrial anion transport proteins in non-insulin-dependent diabetes mellitus

The effect of non-insulin-dependent diabetes mellitus (i.e., NIDDM; type 2 diabetes) on the levels of functional mitochondrial anion transport proteins has been determined utilizing a chemically-induced neonatal model of NIDDM. We hypothesized that moderate insulin deficiency exacerbated by the insulin resistance, which is characteristic of NIDDM, would cause changes in mitochondrial anion transporter function that were similar to those we have previously shown to occur in insulin-dependent diabetes mellitus (i.e., IDDM; type 1 diabetes) (Arch. Biochem. Biophys. 280: 181–191, 1990). Our experimental approach consisted of the extraction of the pyruvate, dicarboxylate and citrate transport proteins from the mitochondrial inner membrane with Triton X-114 using rat liver mitoplasts (prepared from diabetic and control animals) as the starting material, followed by the functional reconstitution of each transporter in a proteoliposomal system. This strategy permitted the quantification of the functional levels of these three transporters in the absence of the complications that arise when such measurements are carried out with intact mitochondria (or mitoplasts). We found that experimental NIDDM did not cause significant changes in the extractable and reconstitutable specific (and total) transport activities of the pyruvate, dicarboxylate, and citrate transporters. These results are in marked contrast to our previous findings obtained using rats with IDDM and negated our hypothesis. The present results, in combination with our earlier findings, allow us to conclude that insulin plays an important role in the regulation of mitochondrial anion transporter function. Accordingly, in this model of NIDDM, where the level of insulin is not profoundly deficient, transporter function is unaltered, whereas in IDDM, where a profound insulinopenia exists, transporter function is altered. Furthermore, the present studies suggest that in the neonatal model of NIDDM the three mitochondrial transporters investigated are neither affected by, nor are they the sites of the well documented hepatic post-receptor insulin resistance which is characteristic of this disease.     

Development and characterization of a novel rat model of type 2 diabetes mellitus: the UC Davis type 2 diabetes mellitus UCD-T2DM rat

The prevalence of type 2 diabetes (T2DM) is increasing, creating a need for T2DM animal models for the study of disease pathogenesis, prevention, and treatment. The purpose of this project was to develop a rat model of T2DM that more closely models the pathophysiology of T2DM in humans. The model was created by crossing obese Sprague-Dawley rats with insulin resistance resulting from polygenic adult-onset obesity with Zucker diabetic fatty-lean rats that have a defect in pancreatic beta-cell function but normal leptin signaling. We have characterized the model with respect to diabetes incidence; age of onset; longitudinal measurements of glucose, insulin, and lipids; and glucose tolerance. Longitudinal fasting glucose and insulin data demonstrated progressive hyperglycemia (with fasting and fed glucose concentrations >250 and >450 mg/dl, respectively) after onset along with hyperinsulinemia resulting from insulin resistance at onset followed by a progressive decline in circulating insulin concentrations, indicative of beta-cell decompensation. The incidence of diabetes in male and female rats was 92 and 43%, respectively, with an average age of onset of 6 mo in males and 9.5 mo in females. Results from intravenous glucose tolerance tests, pancreas immunohistochemistry, and islet insulin content further support a role for beta-cell dysfunction in the pathophysiology of T2DM in this model. Diabetic animals also exhibit glycosuria, polyuria, and hyperphagia. Thus diabetes in the UC Davis-T2DM rat is more similar to clinical T2DM in humans than in other existing rat models and provides a useful model for future studies of the pathophysiology, treatment, and prevention of T2DM.     

Examination of OLETF-derived non-insulin-dependent diabetes mellitus QTL by construction of a series of congenic rats

The Otuska Long-Evans Tokushima Fatty (OLETF) rat is one of the well-characterized animal models for the study of type 2 diabetes. Our previous QTL mapping identified 11 loci responsible for non-insulin-dependent diabetes mellitus (NIDDM) susceptibility in the OLETF rat. Here we generated a series of congenic animals by individually introgressing all 11 OLETF-derived NIDDM loci into a normoglycemic F344 background. Subsequent oral glucose tolerance test revealed that the congenic strains for Nidd1/of, Nidd2/of, Nidd3/of Nidd4/of, Nidd7/of, and Nidd10/of showed significantly higher levels of blood glucose in comparison with parental host strain F344. Furthermore, simultaneously made heterozygote animals for Nidd1/of and Nidd2/of did not increase blood glucose levels, indicating that these loci are recessively inherited as predicted by the QTL analysis. Congenic strains for the other five loci—Nidd5/of, Nidd6/of, Nidd8/of, Nidd9/of, and Nidd11/of—were apparently normoglycemic, presumably owing to heterosis or because the effect of these loci may not be detected unless interactions with other OLETF genes exist. We believe that these congenic strains should provide useful agents for decomposing complex diabetic traits and for positional cloning.     

Identification of novel non-insulin-dependent diabetes mellitus susceptibility loci in the Otsuka Long-Evans Tokushima Fatty rat by MQM-mapping method

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type, non-insulin-dependent diabetes mellitus (NIDDM) in humans. We have previously identified 11 quantitative trait loci (QTLs) responsible for NIDDM susceptibility on Chromosomes (Chrs) 1, 5, 7, 8, 9, 11, 12, 14, and 16 (Nidd1–11/of for Non-insulin-dependent diabetes1–11/oletf) by using the interval mapping method in 160 F₂ progenies obtained by mating the OLETF and the Fischer-344 (F344) rats. MQM-mapping, which was applied for QTL analysis based on multiple-QTL models, is reported to be more powerful than interval mapping, because in the process of mapping one QTL the genetic background, which contains the other QTLs, is controlled. Application of MQM-mapping in the F₂ intercrosses has led to a revelation of three novel QTLs on rat Chrs 5 (Nidd12/of), 7 (Nidd13/of), and 17 (Nidd14/of), in addition to Nidd1–11/of loci. The three QTLs, together with the Nidd1–11/of, account for a total of ∼70% and ∼85% of the genetic variance of the fasting and postprandial glucose levels, respectively, in the F₂. While the OLETF allele corresponds with increased glucose levels as expected for Nidd12 and 14/of, the Nidd13/of exhibits heterosis: heterozygotes showing significantly higher glucose levels than OLETF or F344 homozygotes. There is epistatic interaction between Nidd2 and 14/of. Additionally, our results indicated that the novel QTLs could show no linkage with body weight, but Nidd12/of has an interaction with body weight. Received: 23 February 1999 / Accepted: 3 August 1999     

The role of amylin in the insulin resistance of non-insulin-dependent diabetes mellitus

Decreased responsiveness of glucose metabolism to insulin in skeletal muscle and the liver (insulin resistance or insensitivity) is characteristic of many conditions, including non-insulin-dependent (type II) diabetes mellitus. Most current work in this area centres on the hypothesis that the primary defect is an impairment of insulin binding and/or transduction of the insulin signal in affected tissues. However, studies imply that defects in the post-insulin receptor signaling pathways are of primary importance in the causation of insulin resistance. Amylin, a novel pancreatic hormone, secreted along with insulin from the pancreatic beta-cells, can modulate insulin effects, to produce insulin resistance in skeletal muscle and liver.