Weight reduction increases adipose but decreases cardiac LPL in reduced-obese Zucker rats.
Lipoprotein lipase (LPL) activity and mRNA levels were measured in cardiac muscle and adipose tissue from lean, obese, and weight-stable reduced-obese Zucker rats, both fasted and 2 h after feeding. Fasting epididymal fat LPL activity was substantially higher in obese rats relative to lean rats [6.9 vs. 0.2 nmol free fatty acid (FFA).10(6) cells-1.min-1; P = 0.0001], and was higher still in reduced-obese rats (15.7 nmol FFA.10(6) cells-1.min-1; P = 0.002). Adipose tissue LPL increased with feeding in all three groups. In marked contrast, fasting cardiac muscle LPL was lower in obese rats relative to lean (28.8 vs. 38.5 nmol FFA.g-1.min-1; P = 0.0064) and was lower still in reduced-obese rats (14.5 nmol FFA.g-1.min-1; P = 0.0001). LPL mRNA levels increased in adipose tissue along with enzyme activity; however, the magnitude of the changes were relatively small, suggesting that the primary regulatory steps are posttranslational. Weight reduction studies were also carried out in Sprague-Dawley rats with similar results. These studies show that sustained weight reduction results in coordinate changes in tissue-specific LPL, favoring delivery of lipoprotein triglyceride fatty acids to adipose tissue relative to cardiac muscle and the restoration of energy stores.
Bessesen
D H
DH
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
Robertson
A D
AD
Eckel
R H
RH
D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D008071:Lipoprotein Lipase / Q000235:genetics / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D009765:Obesity / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011924:Rats, Zucker / Q000378:metabolism*; D015431:Weight Loss
D012333:RNA, Messenger; D008071:Lipoprotein Lipase