1208-P: Caloric Restriction Modified Factors Regulating Lipid Storage and Apoptosis in Inguinal but Not Epididymal Adipose Tissue of 24-Month-Old Male Rats Free

Calorie restriction (CR) and the resultant weight-loss are known to improve metabolic health, but the effects of CR on factors regulating white adipose tissue (WAT) metabolic function and remodeling remain unclear. The purpose of this study was to examine the effects of 8 weeks of CR on markers of lipid storage/release, endoplasmic reticulum (ER) stress, and apoptosis in inguinal and epididymal WAT collected from aged rats. We harvested inguinal and epididymal adipose tissue from 24-month-old male Fischer-344 x Brown Norway rats that were either fed an ad libitum chow diet (AL, n=6) or subjected to CR (consuming 35% below AL intake) of the same diet (n=6) for 8 weeks. Using standard immunoblotting methods, inguinal WAT from CR had a greater abundance of phosphorylated hormone sensitive lipase (pHSL) than AL (11.1±6.6 vs. 4.5±3.3 arbitrary units (AU); P=0.05) indicative of elevated lipase activity in CR, and a lower protein abundance of the esterification marker, diacylglycerol acyltransferase (DGAT; 1.0±0.2 vs. 2.4±0.6 AU; P<0.001). Interestingly, protein abundance of the ER stress marker, CCAAT-enhancer-binding protein homologous protein (CHOP) was also significantly lower in CR vs. AL (0.7±0.3 vs. 1.7±0.5 AU; P<0.01), and the protein abundance of Beclin, a marker of autophagy, tended to be lower in CR vs. AL (1.9±0.4 vs. 2.6±0.7 AU, for CR vs. AL; P=0.08). In contrast to these findings for inguinal WAT, there were no detectable differences in protein abundance for any of these markers in epididymal WAT from CR vs. AL.

In summary, CR-mediated responses in WAT of aged rats appeared to be depot-specific and CR may contribute to important metabolic modifications and may impact cellular remodeling of inguinal adipose tissue.