Fasting-induced increases in aquaporin 7 and adipose triglyceride lipase mRNA expression in adipose tissue are attenuated by peroxisome proliferator-activated receptor a deficiency

• Published in: International Journal of Obesity 2007-07, Vol.31 (7), p.1165-1171
• Main Authors: WALKER, C. G, HOLNESS, M. J, GIBBONS, G. F, SUGDEN, M. C
• Format: Article
• Language: English
• Subjects: Adipocytes; Adipose tissue; Aquaporins; Biological and medical sciences; Body fat; Diabetes; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Gene expression; Glucose; Glycerol; Insulin; Medical sciences; Medicine; Metabolic diseases; Metabolism; Metabolites; Obesity; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/sj.ijo.0803555

To investigate the impact of peroxisome proliferator-activated receptor alpha deficiency on gene expression of adipose triglyceride lipase and the glycerol transporter aquaglyceroporin 7 in white adipose tissue in the fed and fasted states in relation to glycerol release by isolated adipocytes. Studies using wild-type and peroxisome proliferator-activated receptor alpha null mice. Hormone and metabolite concentrations, real-time polymerase chain reaction (PCR), basal and stimulated adipocyte lipolysis, estimated by glycerol release. Peroxisome proliferator-activated receptor alpha deficiency blocked the increase in aquaglyceroporin 7 transcript level and attenuated the increase in adipose triglyceride lipase transcript level in white adipose tissue elicited by fasting. Fasting glycerol levels were lower in peroxisome proliferator-activated receptor alpha null than wild-type mice, despite increased mobilization of adipocyte fat reserves in vivo as indicated by reduced adipose tissue masses (three distinct depots) and a significantly lower epididymal adipocyte diameter. Basal net glycerol release was unchanged but beta-adrenergic-stimulated net glycerol release was higher with isolated adipocytes from fasted peroxisome proliferator-activated receptor alpha null mice compared with those of fasted wild-type mice. Peroxisome proliferator-activated receptor alpha deficiency prevents effects of fasting to increase adipocyte aquaglyceroporin 7 gene expression, and influences the regulation of inter-tissue glycerol flux after fasting via lowered adipocyte aquaglyceroporin 7 expression. Lowered gene expression of adipose triglyceride lipase and aquaglyceroporin 7 in peroxisome proliferator-activated receptor alpha null mice is not limiting for adipose triglyceride breakdown in vivo during fasting.