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The effects of testosterone and ageing on skeletal muscle growth and androgen receptor expression

Williams, R (2022) The effects of testosterone and ageing on skeletal muscle growth and androgen receptor expression. Other thesis, Liverpool John Moores University.

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Abstract

Aging is associated with a significant reduction in skeletal muscle mass, termed sarcopenia. As life expectancies and elderly populations continue to increase, so does the prevalence of sarcopenia. Sarcopenia has been associated with depression, frailty, and severe reductions in quality of life in older adults, as well as placing significant strain on healthcare systems. Therefore, there is a clear requirement for effective, preventative treatments, which can easily be self-administered by older adults. Prior studies have suggested that reductions in androgen receptor content occur with aging, and that this may be integral to an age-associated loss of skeletal muscle mass. Testosterone, an androgenic steroid hormone instrumental in the development and maintenance of skeletal muscle mass also decreases with age. Testosterone may potentially increase androgen receptor content, thereby increasing skeletal muscle growth, and responsiveness to other treatments for sarcopenia such as exercise programmes. This thesis aimed to investigate the effects of various testosterone administration protocols on skeletal muscle growth and androgen receptor expression in vitro and determine how these effects differ in aged skeletal muscle tissue. The main findings from this work suggest that 50 nM and 100 nM testosterone accelerates differentiation, inhibits atrophy, and increases androgen receptor mRNA expression in vitro, with greater effects occurring following repeated doses. Conversely, these effects were not present in skeletal muscle cells which had undergone replicative ageing via population doubling, suggesting that there is a limit to the number of doublings cells can undergo before becoming immune to the effects of testosterone administration. Preliminary findings also demonstrated a testosterone induced increase in cellular metabolic activity, which may indicate an increase in cellular viability. In conclusion, this thesis provides evidence for a testosterone induced increase in androgen receptor expression, whilst also demonstrating an ageing induced resistance to the effects of testosterone administration in skeletal muscle.

Item Type: Thesis (Other)
Uncontrolled Keywords: Testosterone; Androgens; Ageing; Aging; Muscle; Hypertrophy; Sarcopenia
Subjects: R Medicine > RC Internal medicine
R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Date Deposited: 26 Jan 2022 10:39
Last Modified: 26 Jan 2022 10:39
DOI or Identification number: 10.24377/LJMU.t.00016152
Supervisors: Owens, D, Sharples, A and Stewart, C
URI: https://researchonline.ljmu.ac.uk/id/eprint/16152

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