Primary male osteoporosis is associated with enhanced glucocorticoid availability

Osteoporosis Due to Hormone Imbalance: An Overview of the Effects of Estrogen Deficiency and Glucocorticoid Overuse on Bone Turnover

Osteoporosis is a serious health issue among aging postmenopausal women. The majority of postmenopausal women with osteoporosis have bone loss related to estrogen deficiency. The rapid bone loss results from an increase in bone turnover with an imbalance between bone resorption and bone formation. Osteoporosis can also result from excessive glucocorticoid usage, which induces bone demineralization with significant changes of spatial heterogeneities of bone at microscale, indicating potential risk of fracture. This review is a summary of current literature about the molecular mechanisms of actions, the risk factors, and treatment of estrogen deficiency related osteoporosis (EDOP) and glucocorticoid induced osteoporosis (GIOP). Estrogen binds with estrogen receptor to promote the expression of osteoprotegerin (OPG), and to suppress the action of nuclear factor-κβ ligand (RANKL), thus inhibiting osteoclast formation and bone resorptive activity. It can also activate Wnt/β-catenin signaling to increase osteogenesis, and upregulate BMP signaling to promote mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts, rather than adipocytes. The lack of estrogen will alter the expression of estrogen target genes, increasing the secretion of IL-1, IL-6, and tumor necrosis factor (TNF). On the other hand, excessive glucocorticoids interfere the canonical BMP pathway and inhibit Wnt protein production, causing mesenchymal progenitor cells to differentiate toward adipocytes rather than osteoblasts. It can also increase RANKL/OPG ratio to promote bone resorption by enhancing the maturation and activation of osteoclast. Moreover, excess glucocorticoids are associated with osteoblast and osteocyte apoptosis, resulting in declined bone formation. The main focuses of treatment for EDOP and GIOP are somewhat different. Avoiding excessive glucocorticoid use is mandatory in patients with GIOP. In contrast, appropriate estrogen supplement is deemed the primary treatment for females with EDOP of various causes. Other pharmacological treatments include bisphosphonate, teriparatide, and RANKL inhibitors. Nevertheless, more detailed actions of EDOP and GIOP along with the safety and effectiveness of medications for treating osteoporosis warrant further investigation.

Born from pre-eclamptic pregnancies predisposes infants to altered cortisol metabolism in the first postnatal year

Pre-eclampsia leads to disturbed fetal organ development, including metabolic syndrome, attributed to altered pituitary-adrenal feedback loop. We measured cortisol metabolites in infants born from pre-eclamptic and normotensive women and hypothesised that glucocorticoid exposure would be exaggerated in the former. Twenty-four hour urine was collected from infants at months 3 and 12. Cortisol metabolites and apparent enzyme activities were analysed by gas chromatography-mass spectrometry. From 3 to 12 months, excretion of THS, THF and pregnandiol had risen in both groups; THF also rose in the pre-eclamptic group. No difference was observed with respect to timing of the visit or to hypertensive status for THE or total F metabolites (P>0.05). All apparent enzymes activities, except 17α-hydroxylase, were lower in infants at 12 compared to 3 months in the normotensive group. In the pre-eclamptic group, only 11β-HSD activities were lower at 12 months.17α-hydroxylase and 11β-HSD activities of tetrahydro metabolites were higher in the pre-eclamptic group at 3 months (P<0.05). 11β-hydroxylase activity increased in the pre-eclamptic group at 12 months. Cortisol excretion, determined by increased 11β-hydroxylase, compensates for high 11β-HSD-dependent cortisol degradation at 3 months and at 12 months counterbalances the reduced cortisol substrate availability in infants born from pre-eclamptic mothers.