|Appears in Collections:||Faculty of Health Sciences and Sport Journal Articles|
|Peer Review Status:||Refereed|
|Title:||Testosterone administration to older men improves muscle function: molecular and physiological mechanisms|
|Authors:||Ferrando, Arny A|
Yeckel, Catherine W
Gilkison, Charles R
Lieberman, Steven A
Wolfe, Robert R
Urban, Randall J
Insulin-like growth factor I
Lean body mass
|Citation:||Ferrando AA, Sheffield-Moore M, Yeckel CW, Gilkison CR, Jiang J, Achacosa A, Lieberman SA, Tipton K, Wolfe RR & Urban RJ (2002) Testosterone administration to older men improves muscle function: molecular and physiological mechanisms, American Journal of Physiology - Endocrinology and Metabolism, 282 (3), pp. E601-E607.|
|Abstract:||We investigated the effects of 6 mo of near-physiological testosterone administration to older men on skeletal muscle function and muscle protein metabolism. Twelve older men (≥60 yr) with serum total testosterone concentrations less than 17 nmol/l (480 ng/dl) were randomly assigned in double-blind manner to receive either placebo (n = 5) or testosterone enanthate (TE; n = 7) injections. Weekly intramuscular injections were given for the 1st mo to establish increased blood testosterone concentrations at 1 mo and then changed to biweekly injections until the 6-mo time point. TE doses were adjusted to maintain nadir serum testosterone concentrations between 17 and 28 nmol/l. Lean body mass (LBM), muscle volume, prostate size, and urinary flow were measured at baseline and at 6 mo. Protein expression of androgen receptor (AR) and insulin-like growth factor I, along with muscle strength and muscle protein metabolism, were measured at baseline and at 1 and 6 mo of treatment. Hematological parameters were followed monthly throughout the study. Older men receiving testosterone increased total and leg LBM, muscle volume, and leg and arm muscle strength after 6 mo. LBM accretion resulted from an increase in muscle protein net balance, due to a decrease in muscle protein breakdown. TE treatment increased expression of AR protein at 1 mo, but expression returned to pre-TE treatment levels by 6 mo. IGF-I protein expression increased at 1 mo and remained increased throughout TE administration. We conclude that physiological and near-physiological increases of testosterone in older men will increase muscle protein anabolism and muscle strength.|
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