11 beta-hydroxysteroid dehydrogenase type 1, growth hormone and the pathophysiology of age related sarcopaenia
Lead Research Organisation:
University of Birmingham
Department Name: Endocrinology
Abstract
With increasing age the body changes in a number of ways including a decrease in muscle mass, increase in abdominal fat and a decrease in bone density. A number of hormones in the blood also change with increasing age. One of the main hormones that decrease with age is growth hormone. Patients who have low growth hormone or too much steroids in their body have very similar changes in body shape to those which occur with ageing. We believe that the changes that occur in body shape and muscle with ageing are due to a decrease in growth hormone and a relative increase in steroid levels in the body‘s tissues. This study aims to look at the levels and role of these hormones directly in human muscle tissue. This will involve blood and urine samples and a taking a small piece of muscle tissue from the thigh of these patients. People who take part will also assessment of body fat and muscle mass and muscle strength. This study will help us understand further the effects of hormones on the ageing process.
Technical Summary
Aims/ Objectives -
1. To define in detail glucocorticoid, growth hormone and IGF-1 secretion and metabolism with increasing age and their interaction.
2. To study the changes in cortisol metabolism within muscle with age and the effects on muscle mass and strength.
3. To correlate the age related changes in body composition and markers of bone remodelling with measures of cortisol secretion and metabolism.
Design/ Methodology
In vitro studies
Expression levels of 11 -HSD1 and 2, H6PDH, glucocorticoid receptor, IGF-1 receptor and GH receptor, IGF-1, Mechano-growth factor and markers of muscle differentiation ( -actin and MHC) will be assessed in human skeletal muscle primary cells (PromoCell, Heidelberg, Germany). Following mRNA and protein preparation, gene expression will be assessed by conventional and semi-quantitative RT-PCR and Western blot analysis, respectively. The activity of 11 -HSD1 will be assessed by incubating cells with tritiated cortisol or cortisone as extensively reported by this group. These cells will then be treated with GH, IGF-1, TNF and IL-1 and glucocorticoids (cortisol+ RU486 (glucorticoid receptor antagonist) and cortisone+ a specific 11 -HSD1 inhibitor) to assess their role in muscle differentiation and regulation of -HDS1. Skeletal muscle cells gene expression and 11 -HSD1 activity will be assessed as described above.
Clinical Studies 60 healthy subjects (30 men and 30 women); Group 1, 20-30 years, Group 2, 40-50 years and Group 3 >65 years. Following an overnight fast basal bloods (lipids, cortisol, cortisone, IGF-1, markers of bone formation and resorption, glucose and insulin) will be taken. Serum samples will be taken every 20mins over a 24-hour period and analyzed for GH, cortisol and cortisone and 24-hour urine collection for assessment of total cortisol metabolites and markers of bone turnover. A prednisolone generation curve will be performed for assessment of hepatic 11 -HSD1 activity. Total and regional body composition and bone mineral density at hip and spine assessed by DEXA and MRI and muscle strength will be assessed by isokinetic dynamometry. A needle muscle biopsy will be taken from the vastus lateralis and mRNA will be extracted to assess tissue expression of genes assessed as above in primary muscle cultures and then correlated with hormone profiles, imaging and muscle strength.
Scientific and medical opportunities - Sarcopaenia is a prevalent clinical problem and this study will yield new data regarding pathogenesis and future treatments. By combining both in vitro and in vivo studies it provides an excellent training platform and foundation to develop as an Academic Endocrinologist.
1. To define in detail glucocorticoid, growth hormone and IGF-1 secretion and metabolism with increasing age and their interaction.
2. To study the changes in cortisol metabolism within muscle with age and the effects on muscle mass and strength.
3. To correlate the age related changes in body composition and markers of bone remodelling with measures of cortisol secretion and metabolism.
Design/ Methodology
In vitro studies
Expression levels of 11 -HSD1 and 2, H6PDH, glucocorticoid receptor, IGF-1 receptor and GH receptor, IGF-1, Mechano-growth factor and markers of muscle differentiation ( -actin and MHC) will be assessed in human skeletal muscle primary cells (PromoCell, Heidelberg, Germany). Following mRNA and protein preparation, gene expression will be assessed by conventional and semi-quantitative RT-PCR and Western blot analysis, respectively. The activity of 11 -HSD1 will be assessed by incubating cells with tritiated cortisol or cortisone as extensively reported by this group. These cells will then be treated with GH, IGF-1, TNF and IL-1 and glucocorticoids (cortisol+ RU486 (glucorticoid receptor antagonist) and cortisone+ a specific 11 -HSD1 inhibitor) to assess their role in muscle differentiation and regulation of -HDS1. Skeletal muscle cells gene expression and 11 -HSD1 activity will be assessed as described above.
Clinical Studies 60 healthy subjects (30 men and 30 women); Group 1, 20-30 years, Group 2, 40-50 years and Group 3 >65 years. Following an overnight fast basal bloods (lipids, cortisol, cortisone, IGF-1, markers of bone formation and resorption, glucose and insulin) will be taken. Serum samples will be taken every 20mins over a 24-hour period and analyzed for GH, cortisol and cortisone and 24-hour urine collection for assessment of total cortisol metabolites and markers of bone turnover. A prednisolone generation curve will be performed for assessment of hepatic 11 -HSD1 activity. Total and regional body composition and bone mineral density at hip and spine assessed by DEXA and MRI and muscle strength will be assessed by isokinetic dynamometry. A needle muscle biopsy will be taken from the vastus lateralis and mRNA will be extracted to assess tissue expression of genes assessed as above in primary muscle cultures and then correlated with hormone profiles, imaging and muscle strength.
Scientific and medical opportunities - Sarcopaenia is a prevalent clinical problem and this study will yield new data regarding pathogenesis and future treatments. By combining both in vitro and in vivo studies it provides an excellent training platform and foundation to develop as an Academic Endocrinologist.