neuropeptide-y and Femoral-Fractures

Our previous study documented that melatonin (MLT) induced the osteogenic differentiation of mesenchymal stem cells (MSCs) and promoted the healing of femoral fractures in rats via the neuropeptide Y (NPY)/neuropeptide Y1 receptor (NPY1R) signaling pathway. MLT treatment upregulated the expression of the zinc uptake transporter zinc transporter 1 (Zip1) in nerve cells. Prior research demonstrated that oral zinc upregulated NPY expression. MSCs were isolated from rat bone marrow and identified using flow cytometry in our study. The results showed that MLT treatment upregulated NPY and NPY1R levels in MSCs with osteogenic differentiation, which was accompanied by upregulated Zip1 expression. However, the MLT-induced osteogenic differentiation of MSCs was reversed after interference of Zip1 expression. It was confirmed by the decreased alkaline phosphatase (ALP) level; downregulated activities of type I collagen α1 chain (COL1A1), osteocalcin (OCN), runt-related transcription factor 2 (Runx2) and ALP; and reduced mineralized nodule formation. MLT promoted fracture healing in rats with femoral fracture, which was accompanied by increased expression of NPY and NPY1R and significantly increased expression of Zip1. In contrast, the silencing of Zip1 expression reversed MLT-mediated fracture healing. In summary, Zip1 participated in the regulation of the NPY/NPY1R signaling pathway via MLT to promote the osteogenic differentiation of MSCs and fracture healing.

Topics: Animals; Cation Transport Proteins; Cell Differentiation; Femoral Fractures; Male; Melatonin; Mesenchymal Stem Cells; Neuropeptide Y; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Receptors, Neuropeptide; Signal Transduction; Up-Regulation; Wound Healing

The function of melatonin (MLT) in promoting fracture healing has been demonstrated in previous studies. However, the molecular mechanism underlying therapeutic effects of MLT is not entirely clear. In this study, mesenchymal stem cells (MSCs) were isolated from rat bone marrow and identified by flow cytometry. We found that MLT treatment upregulated the neuropeptide Y (NPY) and NPY receptor Y1 (NPY1R) expression, and promoted the proliferation and migration of MSCs, which was suppressed by BIBP3226, an inhibitor of NPY1R. Moreover, the levels of NPY and NPY1R in MSCs undergoing osteoblastic differentiation were upregulated after MLT administration. MLT-induced osteoblastic differentiation of MSCs was suppressed by BIBP3226 treatment, as evidenced by decreased levels of alkaline phosphatase (ALP), collagen type I α1 chain, osteocalcin, and runt-related transcription factor 2, downregulated activity of ALP, as well as reduced calcium nodule formation. Furthermore, we demonstrated that MLT could promote fracture healing in a rat model of femoral fracture, which was accompanied by the elevated expression of NPY and NPY1R. The administration of BIBP3226 inhibited fracture healing mediated by MLT. To sum up, our results show that MLT promotes osteoblastic differentiation of MSCs and fracture healing by NPY/NPY1R signaling.

Topics: Alkaline Phosphatase; Animals; Arginine; Cell Differentiation; Collagen Type I; Collagen Type I, alpha 1 Chain; Core Binding Factor Alpha 1 Subunit; Femoral Fractures; Fracture Healing; Male; Melatonin; Mesenchymal Stem Cells; Neuropeptide Y; Osteoblasts; Osteocalcin; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Receptors, Neuropeptide; Signal Transduction

To clarify the effects of low sound pressure level (LSPL) infrasound on local bone turnover and explore its underlying mechanisms, femoral defected rats were stabilized with a single-side external fixator. After exposure to LSPL infrasound for 30min twice everyday for 6 weeks, the pertinent features of bone healing were assessed by radiography, peripheral quantitative computerized tomography (pQCT), histology and immunofluorescence assay. Infrasound group showed a more consecutive and smoother process of fracture healing and modeling in radiographs and histomorphology. It also showed significantly higher average bone mineral content (BMC) and bone mineral density (BMD). Immunofluorescence showed increased expression of calcitonin gene related peptide (CGRP) and decreased Neuropeptide Y (NPY) innervation in microenvironment. The results suggested the osteogenesis promotion effects of LSPL infrasound in vivo. Neuro-osteogenic network in local microenvironment was probably one target mediating infrasonic osteogenesis, which might provide new strategy to accelerate bone healing and remodeling.

Topics: Acoustics; Animals; Bone Density; Bone Remodeling; Calcitonin Gene-Related Peptide; Disease Models, Animal; External Fixators; Femoral Fractures; Femur; Fluorescent Antibody Technique; Fracture Healing; Male; Neuropeptide Y; Osteogenesis; Osteotomy; Pressure; Rats; Rats, Sprague-Dawley; Sound; Time Factors; Tomography, X-Ray Computed