The physiological actions of sex steroids contribute to sexual dimorphism of the skeleton, timing of epiphyseal closure, determination of peak bone mass, maintenance of mineral homeostasis during reproduction, and maintenance of bone mass, architecture, and mineral homeostasis in adults.
Growth hormone (GH) is essential for the regulation of body composition, nutrient metabolism, extra-cellular fluid volume, lean and fat mass, maintenance of muscle mass and strength, myocardial structure and function [ 1- 5].
In addition to muscle mass maintenance, a cluster of miRNA species (miR -23, -103, -107, -278 etc).
Although Akt has an established role in skeletal muscle homeostasis, we find that serum- and glucocorticoid-inducible kinase 1 (SGK1) regulates muscle mass maintenance via downregulation of proteolysis and autophagy as well as increased protein synthesis during hibernation.
Although muscle mass changes influenced the magnitude of the strength changes over time, strength declines in spite of muscle mass maintenance or even gain emphasize the need to explore the contribution of other cellular, neural, or metabolic mediators of strength changes.
This indicates that the loss of weight during the sophomore year was a loss of fat mass with maintenance of fat-free mass.
Because the changes observed in Akt activation and expression cannot explain either the denervation or immobilization phenotypes, we also examined an additional regulator of muscle mass maintenance, SGK.
Compared with the age-matched wild type mouse, the ageing KO mouse shows greater loss of fast muscle force generation and male muscle mass, good maintenance of grip strength, and increased oxidative metabolism and greater force recovery after fatigue [31].
Longitudinal analyses of hip geometry revealed the advantages of eldecalcitol over alfa-calcidol in: increased cortical cross-sectional area; volumetric BMD of the neck and shaft of the femur; bone mass; and maintenance of cortical thickness (probably through mitigating endocortical bone resorption).
With advancing age, the percentage of fat increases relative to that of lean mass, that is, maintenance of weight and BMI would imply an increase of fat mass.
Mutant mice lacking β2-AR have increased bone mass but do not respond to leptin by reduction in bone mass [ 53], while ovariectomized β2-AR null mice fail to lose bone mass, suggesting that maintenance of the sympathetic nervous system in bone may require estrogen, which is essential in regulating bone remodeling via two related receptors, ER α and ER β expressed by osteoblasts.
