Amino acid metabolism in several tissues of the obese Zucker rat as indicated by the tissue accumulation of α-amino[1-14C]isobutyrate
Measurements of the tissue accumulation of α-amino[1-14C]isobutyrate [1-14C]AIB) in lean (+/?) and obese (fa/fa) Zucker rats showed an augmented tissue/plasma ratio in the liver of the obese animals. In contrast, brown adipose tissue AIB accumulation was lower in the fa/fa animals. In response to a 24h starvation period AIB accumulation was significantly elevated in the liver and plasma of the lean animals and was unchanged in the liver of the fa/fa animals. The circulating concentration of alanine and branched-chain amino acids was elevated in the fa/fa animals as compared to their lean counterparts. These observations suggest that amino acid uptake is not involved in the impaired muscle development observed in the obese Zucker rat and that the ability of brown adipose tissue for amino acid utilization is decreased in the obese animals suggesting that this may partially explain the impaired thermoregulatory capacity observed in brown adipose tissue of obese Zucker rats.
Key wordsZucker rat amino acid metabolism skeletal muscle obesity
Unable to display preview. Download preview PDF.
- 4.Zucker LM, Zucker TF: Fatty, a new mutation in the rat. J Hered 52: 275–278 1961Google Scholar
- 6.Lavau M, Bazin R, Guerre-Millo M: Increased capacity for fatty acid synthesis in white and brown adipose tissue from 7-day old obese Zucker pups. Int J Obesity 9: 61–65, 1985Google Scholar
- 7.Dilettsuo B, Wangsness P: Effect of age on hyperphagia of genetically obese Zucker rat. Proc Soc Exp Biol Med 154: 1–5, 1972Google Scholar
- 11.Bertin R, Triconnet M, Portet R: Effects of cold acclimation on the activity of lipoprotein lipase in adipose tissues of genetically obese Zucker rats. Comp Biochem Physiol 81B: 797–801, 1985Google Scholar
- 16.Cleary MP, Vaselli JR: Reduced organ growth when hyperphagia is prevented in genetically obese (fa/fa) Zucker rats. Exp Biol Med 167: 616, 1981Google Scholar
- 23.Cooper GJ, Kohn PG: α-aminoisobutyric acid transport in rat soleus muscle and its modification by membrane stabilizers and insulin. J Physiol (London) 302: 89–105, 1980Google Scholar
- 28.Tews JK, Harper AE: Distribution of α-aminoisobutyric acid in tissues of lean and genetically obese mice. Proc Soc Exptl Biol Med 191: 18–22, 1989Google Scholar
- 32.Wickler SJ, Horwith BA, Stern JS: Regional blood flow in genetically obese rats during nonshivering thermogenesis. Int J Obesity 6: 481–490, 1982Google Scholar