Beta-hydroxy-beta-methyl-butyrate blunts negative age-related changes in body composition, functionality and myofiber di
- PDF / 1,167,222 Bytes
- 11 Pages / 595.28 x 793.7 pts Page_size
- 35 Downloads / 149 Views
RESEARCH ARTICLE
Open Access
Beta-hydroxy-beta-methyl-butyrate blunts negative age-related changes in body composition, functionality and myofiber dimensions in rats Jacob M Wilson1,2, Samuel C Grant3, Sang-Rok Lee1, Ihssan S Masad3,5, Young-Min Park1, Paul C Henning1,4, Jeffery R Stout6, Jeremy P Loenneke7, Bahram H Arjmandi1, Lynn B Panton1 and Jeong-Su Kim1*
Abstract Purpose: To determine the effects of 16 wk. of beta-hydroxy-beta-methylbutyrate (HMB) administration on agerelated changes in functionality and diffusion tensor imaging (DTI) determined myofiber dimensions. Methods: Twelve young (44 wk.), 6 middle-aged (60 wk.), 10 old (86 wk.), and 5 very old (102 wk.) male Fisher-344 rat’s body composition and grip strength were assessed at baseline. Following, 6 young, 6 middle-aged, 5 old and 5 very old rats were sacrificed for baseline myofiber dimensions and gene transcript factor expression in the soleus (SOL) and gastrocnemius (GAS). The remaining 6 young and 5 old rats were given HMB for 16 wk. and then sacrificed. Results: Fat mass increased in the middle-aged control condition (+49%) but not the middle-aged HMB condition. In addition, fat mass declined (-56%) in the old HMB condition but not the old control condition. Normalized strength declined and maintained respectively in the control and HMB conditions from 44 to 60 wk. and increased (+23%) (p < 0.05) from 86 to 102 wk. in only the HMB condition. Declines occurred in myofiber size in all muscles from 44 to 102 wk. in the control condition(-10 to -15%), but not HMB condition. Atrogin-1 mRNA expression in the SOL and GAS muscles was greater in the 102-wk control condition than all other conditions: SOL (+45%) and GAS (+100%). This elevation was blunted by HMB in the 102 wk. old SOL. There was a condition effect in the SOL for myogenin, which significantly increased (+40%) only in the 102-wk. HMB group relative to the 44-wk. group. Conclusions: HMB may blunt age-related losses of strength and myofiber dimensions, possibly through attenuating the rise in protein breakdown. Keywords: Beta-hydroxy-beta-methylbutyrate, Aging, Fat-free mass, Strength, Sarcopenia
Backgrounds In the 20th century, the United States experienced a 57% increase in lifespan (from 49.2 to 76.5 years) [1]. With continued growth per annum life expectancy is projected to rise to approximately 80 and 84 years of age in women and men, respectively, by the year 2050 [1]. It has been shown that there is a 30% loss of muscle tissue that occurs from the 5th to 8th decade of life [2]. * Correspondence: [email protected] 1 Department of Nutrition, Food and Exercise Sciences, The Florida State University, Tallahassee, FL, USA Full list of author information is available at the end of the article
This progressive age-related loss of muscle tissue, strength, and function is termed sarcopenia [3]. Sarcopenia is associated with a greater likelihood of disability, functional impairment in activities of daily living [4,5], increased incidence of falls, insulin resistance [6], and hip fractures [7].
Data Loading...
