Effect Of α-MSH On The Bone Metabolism

ObjectiveTo determin the type of melanocortin receptors in primary osteoblasts. To investigate the effect of a-Melanocyte stimulating hormone (a-MSH) on the content of mouse serum bone-specific alkaline phosphatase (ALP-B) and C-terminal cross-linking telopeptide of type1collagen (CTX-1) and on the expression of osteoporogeterin(OPG) and recetor activator nuclear factor kappa b ligand(RANKL) mRNA on mouse osteoblasts. The effect of a-MSH on the transformation of mesenchymal stem cell into osteoblasts.Methods1. Primary osteoblasts were separated by the mechanical separation and enzyme digestion method and cultured in vitro.2. RT-PCR was used to determine the type of melanocortin receptors in primary osteoblasts.3.a-MSH and sodium chloride were subcutaneously injected into9-week C57BL/6male mice, and the content of serum ALP-B and CTX-1were measured1,3,5day after treatment.4. Primary osteoblasts were treatment with a-MSH,①The primary OBs were treated with different concentration of a-MSH (10"7mol/L,10-8mol/L,10-9mol/L) for12h,②α-MSH of the concentration10-7mol/L was added for6h,12h,24h. Control group was set up at the same time.The expression of OPG and RANKL mRNA were detected by real-time PCR.5. Culturing bone mesenchymal stem cell in vitro.6.Bone mesenchymal stem cells were cultured with osteogenic induction medium and osteogenic induction medium+α-MSH for7,14,21d, and then stained with alizarin red.Result1.RT-PCR showed that MC1R、MC2R、MC4R and MC5R were expressed in primary cultured osteoblasts;2.The content of serum ALP-B were significantly decreased in3and5days after treatment (P<0.05), the content of serum CTX-I were significantly increased in3and 5days after treatment (P<0.05);3. The expression of OPG and RANKL mRNA were significantly increased in a dose and time dependent fasion after incubation with α-MSH.4. Alizarin staining showed that α-MSH and osteoblasts induced liquid cultured bone marrow mesenchymal stem cells compared with osteoblasts induced liquid cultured bone marrow mesenchymal stem cells, in culture for2weeks,3weeks later, the number of calcified nodule formation reduction.Conclusionα-MSH might make the decrease of bone formation, increased bone resorption, resulting in osteopenia...