Effect of Magnetic Nanoparticles on Hormone Level Changes During Perimenopausal Period and Regulation of Bone Metabolism.

This work aimed to explore the effect of nerve magnetic stimulation based on superparamagnetic Fe3O4 nanoparticle (NP) on bone metabolism during the perimenopausal period. First, the multifunctional water-soluble polymer PTMP-PMAA was utilized as the ligand. PTMP-MAA@ Fe3O4 NP with high magnetization was prepared by the co-precipitation method, and NPX diffraction pattern analysis and in vitro stability analysis were implemented. Then, NPs were co-cultured with 293T cells, and the cytotoxicity was detected by the CCK-8 method. Subsequently, 3-month-old female young SD rats and 11~15-month-old natural menopausal SD rats were taken as the research objects. According to the vaginal smear, the rats were randomly rolled into a young control, perimenopausal period model, estrogen treatment, and osteoporosis prevention groups. Rats in the estrogen treatment group were given Premarin suspension by gavage. Rats in the osteoporosis prevention group were injected stereotaxically with PTMP-MAA@ Fe3O4 NP suspension, and a rotating magnetic field was applied to the brain for nerve magnetic stimulation. The rats were sacrificed three days after treatment and brain tissues were taken for pathological analysis. Rat humerus was weighted and dual-energy X-ray was utilized to determine bone density and bone mineral content. Serum was collected and radioimmunoassay and ELISA were employed to detect estradiol (E2), osteocalcin (Boneglaprotein, BGP), oxytocin (OT), bone alkaline phosphatase (BALP), type I collagen carboxy-terminated cross-linked peptide (CTX-I), and tartrate-resistant acid phosphatase (TRACP-5b) in the serum of rats in each group. The results showed that PTMP-MAA@ Fe3O4 NP had good biocompatibility, and the CCK-8 test results showed that PTMP-MAA@ Fe3O4 NP had low cytotoxicity. Compared with the young control group, the humeral dry weight, wet weight, bone density, and bone mineral content, serum E2, OT, and BGP content in the perimenopausal period model group were reduced, while the serum BALP, CTX-I, and TRACP -5b content was increased (P<0.05). It was verified that nerve magnetic stimulation based on PTMP-MAA@ Fe3O4 NP increased the serum estrogen level of female rats during the perimenopausal period, increased the bone density of rats, promoted bone formation, and regulated bone metabolism.