The effect of phenotype on development of brown and white adipose tissue cellularity and nonshivering thermogenesis in the wistar fatty rat

Brown adipose tissue (BAT) has been noted in cadaveric specimens by anatomists for hundreds of years and is now known to be a primary peripheral the expression non-shivering thermogenesis response perturbations diet environment homeothermic species including man animals. The Wistar Fatty Rat (WFR) an animal model obesity, insulin resistance (IR) NIDDM expresses (-fa) obesity trait NIH/Wistar background. This stain reported exhibit impaired thermogenic parameters obese phenotype. Groups lean male WFR rats were maintained hanging wire-bottomed steel cages fed nutritionally complete containing 54% CHO as equal parts cornstarch (ST) sucrose (SUC) (50:60 w/w) plus vitamins, minerals, fiber, essential micronutrients from 22 30 weeks age. Measures body weight monitored measures resting, norepinephrine stimulated VO2 determined. Animals sacrificed decapitation Interscapular BAT depot (IBAT) white (WAT) depots excised their entirety adiposity adipocyte size number per IBAT WAT depots. studies included lipid content dorsal (DOR), epididymal (EPI) visceral retroperitoneal (VRP) Final Body weights, net gain relative significantly greater than littermates throughout study with greatest increase cell VRP depot. number, tissues IBAT:BW ratio >> littermates. Fasting glucose was similar both phenotypes, but fasting Insulin: Glucose (I: G) ratios markedly elevated obese+NIDDM Resting thermic NE Obese+NIDDM. A robust plasma concentrations occurred phenotypes following results this indicate that while development mass cellularity became exaggerated via hyperplasia hypertrophy obese-NIDDM animals, superimposition early hyperphagia stigmata which likely includes significant IR contributing factor. elevations I: G Obese+NIDDM phenotype may further facilitate compromise capacity diabetic animals fully express BAT-mediated contributions NST. Moreover, increased not itself reliable predictor responses environment.