Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0155339 (Brown)
12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disorders of carbohydrate and lipid metabolism have been reported to cluster in patients with essential hypertension and in spontaneously hypertensive rats (SHRs). A deletion in the Cd36 gene on chromosome 4 has recently been implicated in defective carbohydrate and lipid metabolism in isolated adipocytes from SHRs. However, the role of Cd36 and chromosome 4 in the control of blood pressure and systemic cardiovascular risk factors in SHRs is unknown. In the SHR. BN-Il6/Npy congenic strain, we have found that transfer of a segment of chromosome 4 (including Cd36) from the Brown Norway (BN) rat onto the SHR background induces reductions in blood pressure and ameliorates dietary-induced glucose intolerance, hyperinsulinemia, and hypertriglyceridemia. These results demonstrate that a single chromosome region can influence a broad spectrum of cardiovascular risk factors involved in the hypertension metabolic syndrome. However, analysis of Cd36 genotypes in the SHR and stroke-prone SHR strains indicates that the deletion variant of Cd36 was not critical to the initial selection for hypertension in the SHR model. Thus, the ability of chromosome 4 to influence multiple cardiovascular risk factors, including hypertension, may depend on linkage of Cd36 to other genes trapped within the differential segment of the SHR. BN-Il6/Npy strain.
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PMID:Genetics of Cd36 and the clustering of multiple cardiovascular risk factors in spontaneous hypertension. 1037 71

Estrogen regulates the amount of white adipose tissue (WAT) in females, but its role in males and whether WAT effects involve estrogen receptor-alpha (ERalpha) or ERbeta were unclear. We analyzed the role of ERalpha in WAT and brown adipose tissue by comparing these tissues in wild-type (WT) and ERalpha-knockout (alphaERKO) male and female mice. Brown adipose tissue weight was similar in alphaERKO and WT males at all ages. Progressive increases in WAT were seen in alphaERKO males with advancing age. Epididymal, perirenal, and inguinal WAT weighed 139-185% more in alphaERKO than in WT males by 270-360 days of age. Epididymal and perirenal adipocyte size was increased 20% in alphaERKO males. Adipocyte number was 82-168% greater in fat pads of alphaERKO vs. WT males. Compared with WT, 90-day-old alphaERKO females had increases in fat pad weights (54-103%), adipocyte size, and number. Both alphaERKO males and females had insulin resistance and impaired glucose tolerance, similar to humans lacking ERalpha or aromatase. Energy intake was equal in WT and alphaERKO males, indicating that obesity was not induced by hyperphagia. In contrast, energy expenditure was reduced by 11% in alphaERKO compared with WT males, indicating that altered energy expenditure may be important for the observed obesity. In summary, ERalpha absence causes adipocyte hyperplasia and hypertrophy, insulin resistance, and glucose intolerance in both sexes. These results are evidence that estrogen/ERalpha signaling is critical in female and male WAT; obesity in alphaERKO males involves a mechanism of reduced energy expenditure rather than increased energy intake.
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PMID:Increased adipose tissue in male and female estrogen receptor-alpha knockout mice. 1107 86

Abnormalities in carbohydrate and lipid metabolism are common in patients with essential hypertension and in the spontaneously hypertensive rat (SHR). To identify chromosome regions contributing to this clustering of cardiovascular risk factors in the SHR, we searched for quantitative trait loci (QTL) associated with insulin resistance, glucose intolerance, and dyslipidemia by using the HXB/BXH recombinant inbred (RI) strains. Analysis of variance in RI strains suggested significant effects of genetic factors. A genome screening of the RI strains with more than 700 markers revealed QTL significantly associated with insulin resistance on Chromosomes (Chrs) 3 and 19. The Chr 19 QTL was confirmed by testing a previously derived SHR-19 congenic strain: transfer of a Chr 19 segment delineated by markers D19Rat57 and D19Mit7 from the Brown Norway (BN/Cr) strain onto the genetic background of the SHR/Ola was associated with decreased insulin and glucose concentrations and ameliorated insulin resistance at the tissue level. These findings suggest that closely linked genes on Chr 19, or perhaps even a single gene with pleiotropic effects, influence the clustering of metabolic disturbances in the SHR-BN model.
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PMID:Genetic analysis of metabolic defects in the spontaneously hypertensive rat. 1201 13

Studies on genetic determination of the insulin resistance syndrome in rat models revealed several susceptibility loci for features of this complex phenotype, i.e. dyslipidemia, insulin resistance and obesity. We analysed the influence of introgression of the RNO4, RNO20 segments of SHR origin and RNO8 segment of PD/Cub origin (all previously shown to be involved in (dys)regulation of carbohydrate and lipid metabolism) onto the genetic background of a common progenitor, the Brown Norway (BN/Cub) rat. The differential segments were genetically characterized in the BN.PD-D8Rat39/D8Rat35 (BN-Lx, RNO8 congenic), BN.SHR-Il6/Cd36 (BN.SHR4, RNO4 congenic) and BN.PD-D8Rat39/D8Rat3, SHR-D4Mgh2/Cd36,SHR-D20Wox3/D20Mgh5 (BN-Lx 1K, RNO4, 8, 20 triple congenic) strains and their metabolic profiling was performed. After one week of high-sucrose diet, all congenic strains showed substantially higher levels of serum triglycerides and free fatty acids as well as impaired glucose tolerance in comparison with the BN/Cub progenitor strain. The BN-Lx 1K triple congenic strain displayed the most profound dyslipidemia, glucose intolerance and highest increase of triglyceridemia in response to high-sucrose diet overall, though accompanied with the significantly lowest adiposity index. These results further support the role of genes present within the studied chromosomal regions in observed metabolic disturbances. Furthermore, these findings point to the studied loci within the gene-gene and gene-environment interactions involved in pathogenesis of the insulin resistance syndrome. The set of defined congenic strains provides a possibility of assessing individual features of such a complex phenotype.
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PMID:Metabolic characterization of insulin resistance syndrome feature loci in three brown Norway-derived congenic strains. 1211 27

Mutations in the gene encoding seipin cause Berardinelli-Seip congenital lipodystrophy 2, with symptoms including near-absence of adipose tissue and altered glucose tolerance. Radiation hybrid analysis localized the seipin gene (Bscl2) in rat to a major quantitative trait locus in rat chromosome 1 linked to glucose intolerance in the Goto-Kakizaki (GK) rat model of Type 2 diabetes. We determined the genomic organization of Bscl2 and screened coding exons and flanking intron sequences for mutations in GK, Wistar and Brown Norway rats, as well as in the Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rat. Two silent single nucleotide polymorphisms that were identified also were found in non-diabetic rat strains. We conclude that mutations in the gene for seipin are unlikely to contribute to diabetes in GK and OLETF rats.
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PMID:Localization, cDNA sequence and genomic organization of the rat seipin gene (Bscl2) and sequence analysis in inbred rat models of Type 2 diabetes mellitus. 1258 44

Previous linkage and association studies have suggested that a region of human chromosome 6 containing the tumor necrosis factor (TNF)-alpha gene is involved in the pathogenesis of obesity and obesity-associated hypertension. The aim of the present investigation was to establish whether a segment of rat chromosome 20 (RNO20), which also contains the TNF-alpha gene, determines diet-induced changes in adiposity and blood pressure (BP). The results showed that a transfer of the RNO20 segment from the normotensive Brown Norway (BN) rat onto the background of the spontaneously hypertensive rat (SHR) is associated with a significantly greater increase in adiposity, glucose intolerance, circulating leptin levels, and BP during 12-week, high-fat-diet feeding. In contrast, the transfer is not associated with significant changes in these variables during 12-week, normal-diet feeding. In addition, sequencing of the TNF-alpha gene revealed differences between SHR and BN in the 5'- and 3'-regulatory regions of the gene. Subsequent analyses of TNF-alpha gene expression in fat, muscle, and liver, however, did not provide support for the functional involvement of these differences. In summary, the investigated RNO20 segment contains 1 or more gene variants that affect adiposity, glucose tolerance, serum leptin levels, and BP, but only when the animals are exposed to a particular environment, ie, high-fat-diet feeding. Further studies are needed to identify genes mediating these effects. Considering current changes in our lifestyle involving an increased calorie and fat intake, we believe that gene-environment interactions, such as those described here, play an important role in the current epidemic of obesity and obesity-associated hypertension.
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PMID:Segment of rat chromosome 20 regulates diet-induced augmentations in adiposity, glucose intolerance, and blood pressure. 1265 11

Genetic studies in human populations and rodent models have identified regions of human chromosome 1q21-25 and rat chromosome 2 showing evidence of significant and replicated linkage to diabetes-related phenotypes. To investigate the relationship between the human and rat diabetes loci, we fine mapped the rat locus Nidd/gk2 linked to hyperinsulinemia in an F2 cross derived from the diabetic (type 2) Goto-Kakizaki (GK) rat and the Brown Norway (BN) control rat, and carried out its genetic and pathophysiological characterization in BN.GK congenic strains. Evidence of glucose intolerance and enhanced insulin secretion in a congenic strain allowed us to localize the underlying diabetes gene(s) in a rat chromosomal interval of approximately 3-6 cM conserved with an 11-Mb region of human 1q21-23. Positional diabetes candidate genes were tested for transcriptional changes between congenics and controls and sequence variations in a panel of inbred rat strains. Congenic strains of the GK rats represent powerful novel models for accurately defining the pathophysiological impact of diabetes gene(s) at the locus Nidd/gk2 and improving functional annotations of diabetes candidates in human 1q21-23.
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PMID:Quantitative trait locus dissection in congenic strains of the Goto-Kakizaki rat identifies a region conserved with diabetes loci in human chromosome 1q. 1526 47

Genetic studies in experimental crosses derived from the inbred Goto-Kakizaki (GK) rat model of spontaneous diabetes mellitus have identified quantitative trait loci (QTL) for diabetes phenotypes in a large region of rat Chromosome (RNO) 1. To test the impact of GK variants on QTL statistical and biological features, we combined genetic and physiologic studies in a cohort of F(2) hybrids derived from a QTL substitution congenic strain (QTLSCS) carrying a 110-cM GK haplotype of RNO1 introgressed onto the genetic background of the Brown Norway (BN) strain. Glucose intolerance and altered insulin secretion in QTLSCS rats when compared with BN controls were consistent with original QTL features in a GK x BN F(2) cross. Segregating GK alleles in the QTLSCS F(2) cross account for most of these phenotypic differences between QTLSCS and BN rats. However, significant QTL for diabetes traits in both the QTLSCS and GK x BN F(2) cohorts account for a similar small proportion of their variance. Comparing results from these experimental systems provides indirect estimates of the contribution of genetic interactions and environmental factors to QTL architecture as well as locus and biological targets for future post-QTL mapping studies in congenic substrains.
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PMID:Mapping diabetes QTL in an intercross derived from a congenic strain of the Brown Norway and Goto-Kakizaki rats. 1678 36

Insulin resistance is associated with hypertension by mechanisms likely involving the kidney. To determine how the major apical sodium transporter of the thick ascending limb, the bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is regulated by high-fat feeding, we treated young male, Fischer 344 X Brown Norway (F344BN) rats for 8 wk with diets containing either normal (NF, 4%) or high (HF, 36%) fat, by weight, primarily as lard. HF-fed rats had impaired glucose tolerance, increased urine excretion of 8-isoprostane (a marker of oxidative stress), increased protein levels for NKCC2 (50-125%) and the renal outer medullary potassium channel (106%), as well as increased natriuretic response to furosemide (20-40%). To test the role of oxidative stress in this response, in study 2, rats were fed the NF or HF diet plus plain drinking water, or water containing N(G)-nitro-l-arginine methyl ester (l-NAME), a nitric oxide synthase inhibitor (100 mg/l), or tempol, a superoxide dismutase mimetic (1 mmol/l). The combination of tempol with HF nullified the increase in medullary NKCC2, while l-NAME with HF led to the highest expression of medullary NKCC2 (to 498% of NF mean). However, neither of these drugs dramatically affected the elevated natriuretic response to furosemide with HF. Finally, l-NAME led to a marked increase in blood pressure (measured by radiotelemetry), which was significantly enhanced with HF. Mean arterial blood pressure at 7 wk was as follows (mmHg): NF, 100 +/- 2; NF plus l-NAME, 122 +/- 3; and HF plus l-NAME, 131 +/- 2. Overall, HF feeding increased the abundance of NKCC2. Inappropriately high sodium reabsorption in the thick ascending limb via NKCC2 may contribute to hypertension with insulin resistance.
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PMID:Abundance of the Na-K-2Cl cotransporter NKCC2 is increased by high-fat feeding in Fischer 344 X Brown Norway (F1) rats. 1919 25

Dexamethasone (DEX) is known to induce diabetes and dyslipidemia. We have compared fasting triacylglycerol and cholesterol concentrations across 20 lipoprotein fractions and glucose tolerance in control (standard diet) and DEX-treated 7-month-old males of two rat strains, Brown Norway (BN) and congenic BN.SHR-(Il6-Cd36)/Cub (BN.SHR4). These two inbred strains differ in a defined segment of chromosome 4, originally transferred from the spontaneously hypertensive rat (SHR) including the mutant Cd36 gene, a known target of DEX. Compared to BN, the standard-diet-fed BN.SHR4 showed higher cholesterol and triacylglycerol concentrations across many lipoprotein fractions, particularly in small VLDL and LDL particles. Total cholesterol was decreased by DEX by more than 21% in BN.SHR4 contrasting with the tendency to increase in BN (strain*DEX interaction p = 0.0017). Similar pattern was observed for triacylglycerol concentrations in LDL. The LDL particle size was significantly reduced by DEX in both strains. Also, while control BN and BN.SHR4 displayed comparable glycaemic profiles during oral glucose tolerance test, we observed a markedly blunted DEX induction of glucose intolerance in BN.SHR4 compared to BN. In summary, we report a pharmacogenetic interaction between limited genomic segment with mutated Cd36 gene and dexamethasone-induced glucose intolerance and triacylglycerol and cholesterol redistribution into lipoprotein fractions.
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PMID:Pharmacogenetic interaction between dexamethasone and Cd36-deficient segment of spontaneously hypertensive rat chromosome 4 affects triacylglycerol and cholesterol distribution into lipoprotein fractions. 2039 76


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