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Relationship between visceral adiposity and intramyocellular lipid content in two rat models of insulin resistance.

Abstract

High visceral adiposity and intramyocellular lipid levels (IMCL) are both associated with the development of type 2 diabetes. The relationship between visceral adiposity and IMCL levels was explored in diet- and glucocorticoid-induced models of insulin resistance. In the diet-induced model, lean and fa/fa Zucker rats were fed either normal or high-fat (HF) chow over 4 wk. Fat distribution, IMCL content in the tibialis anterior (TA) muscle (IMCL(TA)), and whole body insulin resistance were measured before and after the 4-wk period. The HF diet-induced increase in IMCL(TA) was strongly correlated with visceral fat accumulation and greater glucose intolerance in both groups. The increase in IMCL(TA) to visceral fat accumulation was threefold greater for fa/fa rats. In the glucocorticoid-induced model, insulin sensitivity was impaired with dexamethasone. In vivo adiposity and IMCL(TA) content measurements were combined with ex vivo analysis of plasma and muscle tissue. Dexamethasone treatment had minimal effects on visceral fat accumulation while increasing IMCL(TA) levels approximately 30% (P < 0.05) compared with controls. Dexamethasone increased plasma glucose by twofold and increased the saturated fatty acid content of plasma lipids [fatty acid (CH2)n/omegaCH3 ratio +15%, P < 0.05]. The lipid composition of the TA muscle was unchanged by dexamethasone treatment, indicating that the relative increase in IMCL(TA) observed in vivo resulted from a decrease in lipid oxidation. Visceral adiposity may influence IMCL accumulation in the context of dietary manipulations; however, a "causal" relationship still remains to be determined. Dexamethasone-induced insulin resistance likely operates under a different mechanism, i.e., independently of visceral adiposity.

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  • Authors+Show Affiliations

    ,

    Discovery Technologies Area, Novartis Institutes for Biomedical Research, Inc., Cambridge, MA 02139, USA.

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    Source

    MeSH

    Adipose Tissue
    Animals
    Blood Glucose
    Dexamethasone
    Dietary Fats
    Glucocorticoids
    Insulin Resistance
    Lipids
    Male
    Muscle, Skeletal
    Rats
    Rats, Zucker
    Viscera

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    15328072

    Citation

    Korach-André, M, et al. "Relationship Between Visceral Adiposity and Intramyocellular Lipid Content in Two Rat Models of Insulin Resistance." American Journal of Physiology. Endocrinology and Metabolism, vol. 288, no. 1, 2005, pp. E106-16.
    Korach-André M, Gao J, Gounarides JS, et al. Relationship between visceral adiposity and intramyocellular lipid content in two rat models of insulin resistance. Am J Physiol Endocrinol Metab. 2005;288(1):E106-16.
    Korach-André, M., Gao, J., Gounarides, J. S., Deacon, R., Islam, A., & Laurent, D. (2005). Relationship between visceral adiposity and intramyocellular lipid content in two rat models of insulin resistance. American Journal of Physiology. Endocrinology and Metabolism, 288(1), pp. E106-16.
    Korach-André M, et al. Relationship Between Visceral Adiposity and Intramyocellular Lipid Content in Two Rat Models of Insulin Resistance. Am J Physiol Endocrinol Metab. 2005;288(1):E106-16. PubMed PMID: 15328072.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Relationship between visceral adiposity and intramyocellular lipid content in two rat models of insulin resistance. AU - Korach-André,M, AU - Gao,J, AU - Gounarides,J S, AU - Deacon,R, AU - Islam,A, AU - Laurent,D, Y1 - 2004/08/24/ PY - 2004/8/26/pubmed PY - 2005/3/3/medline PY - 2004/8/26/entrez SP - E106 EP - 16 JF - American journal of physiology. Endocrinology and metabolism JO - Am. J. Physiol. Endocrinol. Metab. VL - 288 IS - 1 N2 - High visceral adiposity and intramyocellular lipid levels (IMCL) are both associated with the development of type 2 diabetes. The relationship between visceral adiposity and IMCL levels was explored in diet- and glucocorticoid-induced models of insulin resistance. In the diet-induced model, lean and fa/fa Zucker rats were fed either normal or high-fat (HF) chow over 4 wk. Fat distribution, IMCL content in the tibialis anterior (TA) muscle (IMCL(TA)), and whole body insulin resistance were measured before and after the 4-wk period. The HF diet-induced increase in IMCL(TA) was strongly correlated with visceral fat accumulation and greater glucose intolerance in both groups. The increase in IMCL(TA) to visceral fat accumulation was threefold greater for fa/fa rats. In the glucocorticoid-induced model, insulin sensitivity was impaired with dexamethasone. In vivo adiposity and IMCL(TA) content measurements were combined with ex vivo analysis of plasma and muscle tissue. Dexamethasone treatment had minimal effects on visceral fat accumulation while increasing IMCL(TA) levels approximately 30% (P < 0.05) compared with controls. Dexamethasone increased plasma glucose by twofold and increased the saturated fatty acid content of plasma lipids [fatty acid (CH2)n/omegaCH3 ratio +15%, P < 0.05]. The lipid composition of the TA muscle was unchanged by dexamethasone treatment, indicating that the relative increase in IMCL(TA) observed in vivo resulted from a decrease in lipid oxidation. Visceral adiposity may influence IMCL accumulation in the context of dietary manipulations; however, a "causal" relationship still remains to be determined. Dexamethasone-induced insulin resistance likely operates under a different mechanism, i.e., independently of visceral adiposity. SN - 0193-1849 UR - https://www.unboundmedicine.com/medline/citation/15328072/Relationship_between_visceral_adiposity_and_intramyocellular_lipid_content_in_two_rat_models_of_insulin_resistance_ L2 - http://www.physiology.org/doi/full/10.1152/ajpendo.00089.2004?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -