The mechanisms of androgen effects on body composition: mesenchymal pluripotent cell as the target of androgen action.
Testosterone supplementation increases muscle mass primarily by inducing muscle fiber hypertrophy; however, the mechanisms by which testosterone exerts its anabolic effects on the muscle are poorly understood. The prevalent view is that testosterone improves net muscle protein balance by stimulating muscle protein synthesis, decreasing muscle protein degradation, and improving the reutilization of amino acids. However, the muscle protein synthesis hypothesis does not adequately explain testosterone-induced changes in fat mass, myonuclear number, and satellite cell number. We postulate that testosterone promotes the commitment of pluripotent stem cells into the myogenic lineage and inhibits their differentiation into the adipogenic lineage. The hypothesis that the primary site of androgen action is the pluripotent stem cell provides a unifying explanation for the observed reciprocal effects of testosterone on muscle and fat mass.
Bhasin
Shalender
S
Division of Endocrinology, Metabolism, and Molecular Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, California 90059, USA. sbhasin@ucla.edu
Taylor
Wayne E
WE
Singh
Rajan
R
Artaza
Jorge
J
Sinha-Hikim
Indrani
I
Jasuja
Ravi
R
Choi
Helen
H
Gonzalez-Cadavid
Nestor F
NF
D000293:Adolescent; D000328:Adult; D001707:Biopsy, Needle; D001823:Body Composition / Q000187:drug effects* / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D024510:Muscle Development / Q000187:drug effects / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000473:pathology*; D009124:Muscle Proteins / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D039904:Pluripotent Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000008:administration & dosage* / Q000502:physiology*
D009124:Muscle Proteins; D013739:Testosterone