Regulation of gene expression and steroidogenesis in skeletal muscle of postmenopausal women : with emphasis on the effects of hormone replacement and power training
Year: 2011
Type: dissertation
Abstract: Finnish summary Diss.The purpose of this study was to assess whether the use of estrogen-containing hormone replacement therapy (HRT) or plyometric power training (PT) has an effect on skeletal muscle properties by affecting global and/or IGF-1-related gene expression.In addition, the systemic and paracrine roles of steroid hormones in the regulation of muscle properties in post-and premenopausal women were investigated.Two different datasets were utilized: the Ex/HRT study, which was a year-long randomized placebo-controlled intervention with control (CO), HRT and PT groups and the Post/Premenop.study, which was a cross-sectional, case-control study.This thesis is largely based on the muscle samples obtained in the two studies in order to determine differences in gene expression and in latter case also in muscle hormone concentration.Samples were available from nine CO, ten HRT and eight PT women who were 50 to 57 years old and early-stage postmenopausal at the onset of the Ex/HRT study and from 13 postmenopausal 61 to 67 years old non-HRT users and 13 premenopausal 29 to 38 years old women not using contraceptives during participation in the Post/Premenop.study.According to the microarray studies, a wide range of changes occurs in muscle gene expression during the first postmenopausal years.In particular gene expression related to cellular catabolic processes, energy metabolism and muscle remodeling was affected.However, both HRT and PT seemed to balance or slow down some of these changes, and can therefore be considered as counteractive treatments.Furthermore, PT induced transcriptional changes in gene expression related to cytoplasm, actin binding and insulin signaling, while HRT affected gene expression related to protein post-translational modifications, proteolysis, cell proliferation and mitochondrial functions.PT and HRT had parallel effects on gene expression related to carbohydrate metabolism and calcium signaling.In addition, HRT was found to affect the gene expression of several genes related to the IGF-1 signaling pathway.The analysis of steroidogenesis in the postand premenopausal women revealed that despite the extensive loss of steroid hormones in circulation, the skeletal muscle tissue of postmenopausal women has higher concentrations of estrogen and testosterone than the same tissue in premenopausal women.However, the postmenopausal women's muscle properties, including size, strength, power and quality, were poorer than those in the premenopausal women.Taken together, the results imply that postmenopausal HRT and PT induce beneficial changes in muscle gene expression, which are manifested as improved or better maintained muscle properties compared to controls.Furthermore, low circulating concentrations of steroid hormones were associated with decrements in skeletal muscle quality which the local steroidogenesis within the postmenopausal women's muscle was not able to counteract.
Author: Eija Pöllänen
Language: English
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2213802678