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Effects of Conjugated Linoleic Acid and Stearic Acid on Apoptosis of the INS-1 β-cells and Pancreatic Islets Isolated from Zucker Obese (fa/fa) Rats

  • Jang, I.S. (Department of Animal Science & Biotechnology, RAIRC, Jinju National University) ;
  • Hwang, D.Y. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Lee, J.E. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Kim, Y.K. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Kang, T.S. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Hwang, J.H. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Lim, C.H. ;
  • Chae, K.R. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA) ;
  • Jeong, J.H. (Department of Hotel Culinary Arts, Ansan College of Technology) ;
  • Cho, J.S. (Laboratory Animal Resources, National Institute of Toxicological Research, Korea FDA)
  • Received : 2002.10.09
  • Accepted : 2003.04.23
  • Published : 2003.07.01

Abstract

To determine whether dietary fatty acids affect pancreatic $\beta$-cell function, the INS-1 $\beta$-cells and the pancreatic islets isolated from Zucker obese (fa/fa) rats were cultured with stearic acid and conjugated linoleic acid (CLA). As a result, DNA fragmentation laddering was substantially decreased in the INS-1 $\beta$-cells and the isolated pancreatic islets cultured with 2 mM CLA compared to those cultured with stearic acid. To investigate the mechanism by which CLA alleviates cell apoptosis under DNA fragmentation assay, we examined mRNA expressions of apoptosis-related proteins including Bax and Bcl-2 associated with cell death agonist and antagonist, respectively, in both INS-1 cells and islets cultured with 2 mM fatty acids. Bax mRNA expression was not altered by either stearic acid or CLA, whereas Bcl-2 mRNA expression was enhanced by CLA when compared to the stearic acid cultures. However, there were no changes in cell apoptosis and apoptotic-regulating gene products in either INS-1 cells or isolated islets treated with or without 2 mM CLA. It is concluded that CLA maintains $\beta$-cell viability via increased Bcl-2 expression compared to the stearic acid cultures, which may help to alleviate, at least somewhat, the onset of NIDDM in the physiological status. More detailed study is still needed to elucidate the effect of CLA on the prevention of fatty acid-induced $\beta$-cell apoptosis.

Keywords

INS-1 $\beta$-cells;Pancreatic Islets;CLA;Apoptosis

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