Abstract
Increased total fat mass (FM) and visceral fat (VF) may account in part for age-associated decrease in hepatic insulin action. This study determined whether preventing the changes in body fat distribution abolished this defect throughout aging. We studied the F1hybrid of Brown Norway-Fischer 344 rats ( n = 29), which we assigned to caloric restriction (CR) or fed ad libitum (AL). CR (55% of the calories consumed by AL) was initiated and used at 2 mo to prevent age-dependent increases in FM and VF. AL rats were studied at 2, 8, and 20 mo; CR rats were studied at 8 and 20 mo. VF and FM remained unchanged throughout aging in CR rats. AL-fed rats at 8 and 20 mo had over fourfold higher FM and VF compared with both CR groups. Insulin clamp studies (3 mU ⋅ kg−1⋅ min−1with somatostatin) were performed to assess hepatic insulin sensitivity. Prevention of fat accretion resulted in a marked improvement in insulin action in the suppression of hepatic glucose production (HGP) (6.3 ± 0.3 and 7.2 ± 1.2 mg ⋅ kg−1⋅ min−1in 8- and 20-mo CR rats vs. 8.3 ± 0.5 and 10.8 ± 0.9 mg ⋅ kg−1⋅ min−1in 8- and 20-mo AL rats, respectively). The rate of gluconeogenesis (by enrichment of hepatic uridine diphosphate glucose and phospho enolpyruvate pools by [14C]lactate) was unchanged in all groups. The improvement in hepatic insulin action in the CR group was mostly due to effective suppression of glycogenolysis (4.4 ± 0.3 and 4.9 ± 0.3 mg ⋅ kg−1⋅ min−1in 8- and 20-mo CR rats vs. 5.8 ± 0.6 and 8.2 ± 1.0 mg ⋅ kg−1⋅ min−1in 8- and 20-mo AL rats, respectively). The results demonstrated the preservation of hepatic insulin action in aging CR rats. Therefore, body fat and its distribution are major determinants of age-associated hepatic insulin resistance.
Bibliography
Gupta, G., Cases, J. A., She, L., Ma, X.-H., Yang, X.-M., Hu, M., Wu, J., Rossetti, L., & Barzilai, N. (2000). Ability of insulin to modulate hepatic glucose production in aging rats is impaired by fat accumulation. American Journal of Physiology-Endocrinology and Metabolism, 278(6), E985âE991.
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Dates
Type | When |
---|---|
Created | 7 years, 8 months ago (Dec. 22, 2017, 2:53 a.m.) |
Deposited | 3 years ago (Aug. 10, 2022, 9:34 p.m.) |
Indexed | 2 months, 1 week ago (June 25, 2025, 9:32 a.m.) |
Issued | 25 years, 3 months ago (June 1, 2000) |
Published | 25 years, 3 months ago (June 1, 2000) |
Published Print | 25 years, 3 months ago (June 1, 2000) |
@article{Gupta_2000, title={Ability of insulin to modulate hepatic glucose production in aging rats is impaired by fat accumulation}, volume={278}, ISSN={1522-1555}, url={http://dx.doi.org/10.1152/ajpendo.2000.278.6.e985}, DOI={10.1152/ajpendo.2000.278.6.e985}, number={6}, journal={American Journal of Physiology-Endocrinology and Metabolism}, publisher={American Physiological Society}, author={Gupta, Gaurav and Cases, Jane A. and She, Li and Ma, Xiao-Hui and Yang, Xiao-Man and Hu, Meizu and Wu, Jeanie and Rossetti, Luciano and Barzilai, Nir}, year={2000}, month=jun, pages={E985–E991} }