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Mol. Cells 2012; 34(5): 439-448

Published online November 6, 2012

https://doi.org/10.1007/s10059-012-0196-x

© The Korean Society for Molecular and Cellular Biology

β-Hydroxy-β-Methylbutyrate Did Not Enhance High Intensity Resistance Training-Induced Improvements in Myofiber Dimensions and Myogenic Capacity in Aged Female Rats

Jeong-Su Kim1,2,*, Young-Min Park1, Sang-Rok Lee1, Ihssan S. Masad3, Andy V. Khamoui1,2, Edward Jo1,2, Bong-Sup Park1, Bahram H. Arjmandi1,2, Lynn B. Panton1,2, Won Jun Lee1,4, and Samuel C. Grant2,3

1Department of Nutrition, Food, and Exercise Sciences, The Florida State University, Tallahassee, FL, USA, 2The Center for Advancing Exercise and Nutrition Research on Aging, The Florida State University, Tallahassee, FL, USA, 3The National High Magnetic Field Laboratory and Department of Chemical and Biomedical Engineering, The Florida State University, Tallahassee, FL, USA, 4Department of Exercise Science, Ewha Womans University, Seoul 120-749, Korea

Correspondence to : *Correspondence: jkim6@fsu.edu

Received: August 2, 2012; Revised: August 30, 2012; Accepted: September 20, 2012

Abstract

Older women exhibit blunted skeletal muscle hypertro-phy following resistance training (RT) compared to other age and gender cohorts that is partially due to an impaired regenerative capacity. In the present study, we examined whether ?-hydroxy-?-methylbutyrate (HMB) provision to aged female rodents would enhance regenerative mechanisms and facilitate RT-induced myofiber growth. Nineteen-month old female Sprague-Dawley rats were randomly divided into three groups: HMB (0.48 g/kg/d; n = 6), non-HMB (n = 6), and control (n = 4). HMB and non-HMB groups underwent RT every third day for 10 weeks using a ladder climbing apparatus. Whole body strength, grip strength, and body composition was evaluated before and after RT. The gastrocnemius and soleus muscles were analyzed using magnetic resonance diffusion tensor imaging, RT-PCR, and immunohistochemistry to determine myofiber dimensions, transcript expression, and satellite cells/myonuclei, respectively. ANOVAs were used with sig-nificance set at p < 0.05. There were significant time effects (pre vs. post) for whole body strength (+262%), grip strength (+17%), lean mass (+20%), and fat mass (-19%). Both RT groups exhibited significant increases in the mean myofiber cross-sectional area (CSA) in the gas-trocnemius and soleus (+8-22%) compared to control. Moreover, both groups demonstrated significant increases in the numbers of satellite cells (+100-108%) and myonuclei (+32%) in the soleus but not the gastrocnemius. A significant IGF-I mRNA elevation was only observed in soleus of the HMB group (+33%) whereas MGF and myogenin increased significantly in both groups (+32-40%). Our findings suggest that HMB did not further enhance intense RT-mediated myogenic mechanisms and myofiber CSA in aged female rats.

Keywords aging, HMB, ladder climbing, magnetic resonance, satellite cell, sarcopenia

Article

Research Article

Mol. Cells 2012; 34(5): 439-448

Published online November 30, 2012 https://doi.org/10.1007/s10059-012-0196-x

Copyright © The Korean Society for Molecular and Cellular Biology.

β-Hydroxy-β-Methylbutyrate Did Not Enhance High Intensity Resistance Training-Induced Improvements in Myofiber Dimensions and Myogenic Capacity in Aged Female Rats

Jeong-Su Kim1,2,*, Young-Min Park1, Sang-Rok Lee1, Ihssan S. Masad3, Andy V. Khamoui1,2, Edward Jo1,2, Bong-Sup Park1, Bahram H. Arjmandi1,2, Lynn B. Panton1,2, Won Jun Lee1,4, and Samuel C. Grant2,3

1Department of Nutrition, Food, and Exercise Sciences, The Florida State University, Tallahassee, FL, USA, 2The Center for Advancing Exercise and Nutrition Research on Aging, The Florida State University, Tallahassee, FL, USA, 3The National High Magnetic Field Laboratory and Department of Chemical and Biomedical Engineering, The Florida State University, Tallahassee, FL, USA, 4Department of Exercise Science, Ewha Womans University, Seoul 120-749, Korea

Correspondence to:*Correspondence: jkim6@fsu.edu

Received: August 2, 2012; Revised: August 30, 2012; Accepted: September 20, 2012

Abstract

Older women exhibit blunted skeletal muscle hypertro-phy following resistance training (RT) compared to other age and gender cohorts that is partially due to an impaired regenerative capacity. In the present study, we examined whether ?-hydroxy-?-methylbutyrate (HMB) provision to aged female rodents would enhance regenerative mechanisms and facilitate RT-induced myofiber growth. Nineteen-month old female Sprague-Dawley rats were randomly divided into three groups: HMB (0.48 g/kg/d; n = 6), non-HMB (n = 6), and control (n = 4). HMB and non-HMB groups underwent RT every third day for 10 weeks using a ladder climbing apparatus. Whole body strength, grip strength, and body composition was evaluated before and after RT. The gastrocnemius and soleus muscles were analyzed using magnetic resonance diffusion tensor imaging, RT-PCR, and immunohistochemistry to determine myofiber dimensions, transcript expression, and satellite cells/myonuclei, respectively. ANOVAs were used with sig-nificance set at p < 0.05. There were significant time effects (pre vs. post) for whole body strength (+262%), grip strength (+17%), lean mass (+20%), and fat mass (-19%). Both RT groups exhibited significant increases in the mean myofiber cross-sectional area (CSA) in the gas-trocnemius and soleus (+8-22%) compared to control. Moreover, both groups demonstrated significant increases in the numbers of satellite cells (+100-108%) and myonuclei (+32%) in the soleus but not the gastrocnemius. A significant IGF-I mRNA elevation was only observed in soleus of the HMB group (+33%) whereas MGF and myogenin increased significantly in both groups (+32-40%). Our findings suggest that HMB did not further enhance intense RT-mediated myogenic mechanisms and myofiber CSA in aged female rats.

Keywords: aging, HMB, ladder climbing, magnetic resonance, satellite cell, sarcopenia

Mol. Cells
Jun 30, 2023 Vol.46 No.6, pp. 329~398
COVER PICTURE
The cellular proteostasis network is adaptively modulated upon cellular stress, thereby protecting cells from proteostasis collapse. Heat shock induces the translocation of misfolded proteins and the chaperone protein HSP70 into nucleolus, where nuclear protein quality control primarily occurs. Nuclear RNA export factor 1 (green), nucleolar protein fibrillarin (red), and nuclei (blue) were visualized in NIH3T3 cells under basal (left) and heat shock (right) conditions (Park et al., pp. 374-386).

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