Interactions of conjugated linoleic acid and lipoic acid on insulin action in the obese Zucker rat

Mary K. Teachey, Zachary C. Taylor, Thomas Maier, Vitoon Saengsirisuwan, Julie A. Sloniger, Stephan Jacob, Martin J. Klatt, Arne Ptock, Klaus Kraemer, Oliver Hasselwander, Erik J. Henriksen

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21 Scopus citations

Abstract

The fatty acid conjugated linoleic acid (CLA) and the antioxidant R-(+)-α-lipoic acid (R-ALA) individually enhance glucose tolerance and insulin action on skeletal muscle glucose transport in the insulin-resistant obese Zucker rat. To date, no study has assessed the potential interactions between these 2 interventions in treating insulin resistance. The present study was designed to determine whether chronic treatment with CLA and R-ALA in combination would enhance skeletal muscle glucose transport to a greater extent than either intervention individually. CLA, R-ALA, or a combination treatment of R-ALA and CLA were administered to female obese Zucker rats for 20 days at low or high doses. Whereas low-dose R-ALA (10 mg/kg body weight) alone did not alter muscle glucose transport, low-dose CLA (0.3 g/kg) induced a significant increase (38%, P > .05) in insulin-mediated glucose transport in epitrochlearis, but not in soleus. Low-dose combination therapy brought about the greatest enhancement of insulin-mediated glucose transport in epitrochlearis (77%) and soleus (54%), with the latter effect being associated with a 50% reduction in protein carbonyls (an index of tissue oxidative stress) and a 33% diminution in muscle triglycerides. High-dose treatments with CLA (1.5 g/kg), R-ALA (50 mg/kg), and the combination of CLA and R-ALA elicited increases in insulin-mediated glucose transport in epitrochlearis (57%, 58%, and 77%) and soleus (32%, 35%, and 54%). However, whereas the individual high-dose treatments with CLA and R-ALA reduced protein carbonyls (63% and 49%) and triglycerides (29% and 28%) in soleus, no further reductions were observed with the high-dose combination treatment groups. These findings support a significant interaction between low doses of CLA and R-ALA for enhancement of insulin action on skeletal muscle glucose transport, possibly via reductions in muscle oxidative stress and in lipid storage.

Original languageEnglish (US)
Pages (from-to)1167-1174
Number of pages8
JournalMetabolism: Clinical and Experimental
Volume52
Issue number9
DOIs
StatePublished - Sep 1 2003

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ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Cite this

Teachey, M. K., Taylor, Z. C., Maier, T., Saengsirisuwan, V., Sloniger, J. A., Jacob, S., Klatt, M. J., Ptock, A., Kraemer, K., Hasselwander, O., & Henriksen, E. J. (2003). Interactions of conjugated linoleic acid and lipoic acid on insulin action in the obese Zucker rat. Metabolism: Clinical and Experimental, 52(9), 1167-1174. https://doi.org/10.1016/S0026-0495(03)00145-8