RESUMEN
Obesity, a multifactorial disorder, results from a chronic imbalance of energy intake vs. expenditure. Apart from excessive consumption of high calorie diet, genetic predisposition also seems to be equally important for the development of obesity. However, the role of genetic predisposition in the etiology of obesity has not been clearly delineated. The present study addresses this problem by selecting three rat strains (WNIN, F-344, SD) with different genetic backgrounds and exposing them to high calorie diets. Rat strains were fed HF, HS, and HFS diets and assessed for physical, metabolic, biochemical, inflammatory responses, and mRNA expression. Under these conditions: significant increase in body weight, visceral adiposity, oxidative stress and systemic pro-inflammatory status; the hallmarks of central obesity were noticed only in WNIN. Further, they developed altered glucose and lipid homeostasis by exhibiting insulin resistance, impaired glucose tolerance, dyslipidemia and fatty liver condition. The present study demonstrates that WNIN is more prone to develop obesity and associated co-morbidities under high calorie environment. It thus underlines the cumulative role of genetics (nature) and diet (nurture) towards the development of obesity, which is critical for understanding this epidemic and devising new strategies to control and manage this modern malady.
Asunto(s)
Dieta Alta en Grasa/efectos adversos , Dislipidemias/etiología , Hígado Graso/etiología , Intolerancia a la Glucosa/genética , Obesidad/genética , Animales , Peso Corporal , Ingestión de Energía , Resistencia a la Insulina , Masculino , Obesidad/inducido químicamente , Obesidad/complicaciones , Estrés Oxidativo , Ratas , Especificidad de la EspecieRESUMEN
WNIN (Wistar/NIN) is an inbred rat strain maintained at National Institute of Nutrition (NIN) for more than 90 years, and WNIN/Ob is an obese mutant originated from it. To determine their genetic relatedness with major rat strains in biomedical research, they were genotyped at various marker loci. The recently identified markers for albino and hooded mutations which clustered all the known albino rats into a single lineage also included WNIN and WNIN/Ob rats. Genotyping using microsatellite DNA markers and phylogenetic analysis with 49 different rat strains suggested that WNIN shares a common ancestor with many Wistar originated strains. Fst estimates and Fischer's exact test suggest that WNIN rats differed significantly from all other strains tested. WNIN/Ob though shows hyper-leptinemia, like Zucker fatty rat, did not share the Zucker fatty rat mutation. The above analyses suggest WNIN as a highly differentiated rat strain and WNIN/Ob a novel obese mutant evolved from it.
Asunto(s)
Investigación Biomédica , Filogenia , Ratas Endogámicas/genética , Ratas Mutantes/genética , Animales , Modelos Animales de Enfermedad , Genotipo , Masculino , Obesidad/genética , Ratas , Ratas Wistar , Ratas ZuckerRESUMEN
WNIN/Obese (WNIN/Ob) rat a new mutant model of metabolic syndrome was identified in 1996 from an inbred Wistar rat strain, WNIN. So far several papers are published on this model highlighting its physical, biochemical and metabolic traits. WNIN/Ob is leptin resistant with unaltered leptin or its receptor coding sequences--the two well-known candidate genes for obesity. Genotyping analysis of F2 progeny (raised from WNIN/Ob × Fisher--344) in the present study localized the mutation to a recombinant region of 14.15cM on chromosome 5. This was further corroborated by QTL analysis for body weight, which narrowed this region to 4.43 cM with flanking markers D5Rat256 & D5Wox37. Interval mapping of body weight QTL shows that the LOD score peak maps upstream of leptin receptor and shows an additive effect suggesting this as a novel mutation and signifying the model as a valuable resource for studies on obesity and metabolic syndrome.