Endocrine Abstracts

Global knockout models of the androgen receptor (ARKO) illustrates the many roles androgens and their receptor have in the development of male reproductive organs and the gender differences in many features like the musculoskeletal system. However, neither the global ARKO nor orchidectomy models discriminate between direct and indirect effects of androgens. To determine direct and indirect effects of androgens on muscle, we developed a muscle-specific ARKO (called satARKO for ...

It is well established that sex steroid deficiency induces bone loss, resulting in osteoporosis. Consequently, global androgen receptor knock out (ARKO) mice have trabecular and cortical osteopenia. Bone cell-specific ARKOs however, have a much less pronounced bone phenotype, suggesting that androgens have an influence on processes in other systems or organs which in turn have an impact on bone metabolism. The kidney is a likely candidate, as it plays an important role in calc...

Aims: We have previously shown that orchidectomy (ORX) in adult mice induces hypercalciuria and upregulation of renal Ca2+ and PO43− transporters, but also bone loss already after 2 weeks. Pretreatment with risedronate inhibited bone resorption and hypercalciuria but confirmed the upregulation of renal Ca2+ and PO43− transporters, suggesting bone-independent renal effects of androgens. We hypothesize...

Introduction: Pubertal sex steroids are indispensable for peak bone mass acquisition as well as skeletal sexual dimorphism. In males, both androgen receptor (AR) and estrogen receptor alpha (ERα) are required for optimal periosteal cortical bone expansion, while estrogens limit bone size in females. In early puberty, estrogens directly stimulate longitudinal growth via ERα in cartilage, but also indirectly via growth hormone (GH) and insulin-like growth factor I (IGF...

Sex hormone-binding globulin (SHBG) is a high-affinity binding protein for androgens and estrogens. According to the “free hormone hypothesis”, SHBG regulates the free sex steroid fraction and restricts androgen bioactivity. SHBG has also been independently associated with diabetes, osteoporosis etc., but whether this represents causality or residual confounding remains unconfirmed. We studied mice overexpressing human SHBG. Using multiligand liquid chromatography ta...