A clinical herbal prescription Gu-Shu-Kang capsule exerted beneficial effects on the musculoskeletal system of dexamethasone-treated mice by acting on tissue IGF-1 signalling pathway.

CONTEXT: Gu-Shu-Kang (GSK) is a clinical traditional Chinese medicine prescription for the treatment of primary osteoporosis. OBJECTIVE: This study investigates the protection of GSK against dexamethasone (Dex)-induced disturbance of musculoskeletal system in male mice and to identify the underlying mechanism. MATERIALS AND METHODS: Male C57BL/6 mice in Dex-treated groups were orally administered (i.g.) with vehicle, low dose (0.38 g/kg), middle dose (0.76 g/kg), or high dose (1.52 g/kg) of GSK for 8 weeks. A control group was designed without any treatment. The quadriceps femoris, tibialis anterior and gastrocnemius were harvested. Molecular expression was determined by RT-PCR and immunoblotting. RESULTS: Treatment with GSK enhanced weight-loaded swimming time (from 411.7 ± 58.4 s in Dex group to 771.4 ± 87.3 s in GSK-M) and grip strength (from 357.8 ± 23.9 g in Dex group to 880.3 ± 47.6 g in GSK-M). GSK produced a rise in cross-sectional area of myofibers and promoted a switching of glycolytic-to-oxidative myofiber. The administration with GSK affected expression of muscle regulatory factors shown by the down-regulation in MuRF-1 and atrogin-1 and the up-regulation in myogenic differentiation factor (MyoD) and myosin heavy chain (MHC). GSK stimulated tissue IGF-1 signalling pathway (IGF-1R/PI3K/Akt), not only in skeletal muscle but also in bone associated with the amelioration of trabecular bone mineral density and the improvement of osteogenesis. CONCLUSIONS: These findings revealed the potential mechanisms involved in the beneficial effects of Gu-Shu-Kang on musculoskeletal system in mice with challenging to dexamethasone, and this prescription may have applications in management for muscle atrophy and osteoporosis triggered by glucocorticoid.

Eldecalcitol protected osteocytes against ferroptosis of D-gal-induced senescent MLO-Y4 cells and ovariectomized mice.

BACKGROUND: Active vitamin D analog eldecalcitol is clinically applied in treatment of postmenopausal osteoporosis. This study aims to determine the role of eldecalcitol in the protection of osteocytes from senescence and the associated ferroptosis. METHODS: The MLO-Y4 osteocytes were exposed to D-gal inducing senescence. The ovariectomized (OVX) mice treated with D-gal using as an aging inducer were intraperitoneally injected with eldecalcitol. The multiplexed confocal imaging, fluorescence in situ hybridization and transmission electron microscopy were applied in assessing osteocytic properties. Immunochemical staining and immunoblotting were carried out to detect abundance and expression of molecules. RESULTS: The ablation of vitamin D receptor led to a reduction in amounts of osteocytes, a loss of dendrites, an increase in mRNA expression of SASP factors and in protein expression of senescent factors, as well as changes in mRNA expression of ferroptosis-related genes (PTGS2 & RGS4). Eldecalcitol reversed senescent phenotypes of MLO-Y4 cells shown by improving cell morphology and density, decreasing ß-gal-positive cell accumulation, and down-regulating protein expression (P16, P21 & P53). Eldecalcitol reduced intracellular ROS and MDA productions, elevated JC-1 aggregates, and up-regulated expression of Nrf2 and GPX4. Eldecalcitol exhibited osteopreserve effects in D-gal-induced aging OVX mice. The confocal imaging displayed its improvement on osteocytic network organization. Eldecalcitol decreased the numbers of senescent osteocytes at tibial diaphysis by SADS assay and attenuated mRNA expression of SASP factors as well as down-regulated protein expression of senescence-related factors and restored levels of ferroptotic biomarkers in osteocytes-enriched bone fraction. It reduced 4-HNE staining area, stimulated Nrf2-positive staining, and promoted nuclear translocation of Nrf2 in osteocytes of mice as well as inhibited and promoted protein expression of 4-HNE and Nrf2, respectively, in osteocytes-enriched bone fraction. CONCLUSIONS: The present study revealed the ameliorative effects of eldecalcitol on senescence and the associated ferroptosis of osteocytes, contributing to its preservation against osteoporosis of D-gal-induced senescent ovariectomized mice.