Fig. 1
Relationships between hormones, signal pathways, bone-derived modulators and bone mass density. Leptin has a direct anabolic effect on osteoblasts while PTH exerts both anabolic and catabolic actions on bone via regulating the circulating calcium levels. DKK1 and SOST may have an adverse effect on BMD by inhibiting the Wnt/β-catenin pathway; on the opposite, OPG, as an inhibitor of RANKL/RANK pathway, may exert a beneficial effect on BMD. FGF23 regulates peripheral levels of inorganic phosphorous and 1,25-dihydroxyvitamin D3 and may be associated low BMD. OC is a bone turnover marker associated with decreased bone mineral density. OPN can promote bone resorption via binding osteoclasts to the mineral matrix of bones and leads to low BMD. Present study suggested that six repeated ketamine infusions increased the levels of leptin and OPG, and decreased the levels of PTH, SOST, FGF23, OC and OPN in the whole sample of patients with depression. And leptin levels had significant sex differences at each timepoint across the treatment (female > male). DKK1: Dickkopf-related protein 1; OPG: osteoprotegerin; OC: osteocalcin; OPN: osteopontin; SOST: sclerostin; PTH: parathyroid hormone; FGF23: fibroblast growth factor 23; Wnt: wingless type; RANKL: receptor activator of NF-κB ligand