Effects of l-arginine and l-NAME supplementation on mRNA, protein expression and activity of catalase and glutathione peroxidase in brown adipose tissue of rats acclimated to different temperatures

Study elucidates molecular mechanisms underlying activation of catalase and glutathione peroxidase (GSH-Px) during cold-exposure by examining time-dependent changes in their mRNA, protein expression and activity, in interscapular brown adipose tissue (IBAT) of rats kept at room temperature (22 +/- 1 degrees C), or subjected to cold (4 +/- 1 degrees C) for 1, 3, 7, 12, 21 and 45 days. To examine involvement of nitric oxide (*NO) in catalase and GSH-Px regulation, rats were treated with L-arginine or N((1))-nitro-L-arginine-methyl ester (L-NAME). In all groups, cold increased catalase mRNA, protein expression and activity from day 3 to day 45 of acclimation. However, cold-acclimation increased GSH-Px mRNA content on day 3, protein content from day 1 to day 45 and activity no sooner than on day 45. At room temperature, 21- and 45-day L-arginine and L-NAME supplementation increased catalase and GSH-Px mRNA expression, but decreased their activity. Concomitantly, catalase protein content decreased, while GSH-Px protein expression increased compared to control. Data show that cold is dominant stimulus that determines IBAT catalase and GSH-Px responses, by setting tissue metabolic state. In thermogenic-active tissue, catalase is regulated on transcriptional level, while GSH-Px is regulated post-translationally. On the other side, it was shown that *NO affects catalase and GSH-Px only in thermogenic-inactive tissue. (C) 2011 Elsevier Ltd. All rights reserved. Ministry of Science and Technological Development of the Republic of Serbia [173055]; COST, Action [FA0602]