ABSTRACT
The application of pulsed electromagnetic fields (PEMFs) in the prevention and treatment of osteoporosis has long been an area of interest. However, the clinical application of PEMFs remains limited because of the poor understanding of the PEMF action mechanism. Here, we report that PEMFs promote bone formation by activating soluble adenylyl cyclase (sAC), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and cAMP response element-binding protein (CREB) signaling pathways. First, it was found that 50 Hz 0.6 millitesla (mT) PEMFs promoted osteogenic differentiation of rat calvarial osteoblasts (ROBs), and that PEMFs activated cAMP-PKA-CREB signaling by increasing intracellular cAMP levels, facilitating phosphorylation of PKA and CREB, and inducing nuclear translocation of phosphorylated (p)-CREB. Blocking the signaling by adenylate cyclase (AC) and PKA inhibitors both abolished the osteogenic effect of PEMFs. Second, expression of sAC isoform was found to be increased significantly by PEMF treatment. Blocking sAC using sAC-specific inhibitor KH7 dramatically inhibited the osteogenic differentiation of ROBs. Finally, the peak bone mass of growing rats was significantly increased after 2 months of PEMF treatment with 90 min/day. The serum cAMP content, p-PKA, and p-CREB as well as the sAC protein expression levels were all increased significantly in femurs of treated rats. The current study indicated that PEMFs promote bone formation in vitro and in vivo by activating sAC-cAMP-PKA-CREB signaling pathway of osteoblasts directly or indirectly.
Subject(s)
Enzyme Inhibitors/pharmacology , Magnetic Field Therapy , Osteogenesis/radiation effects , Osteoporosis/therapy , Adenylyl Cyclase Inhibitors/pharmacology , Adenylyl Cyclases/genetics , Adenylyl Cyclases/pharmacology , Animals , Bone Density/radiation effects , Cell Differentiation/radiation effects , Cyclic AMP/antagonists & inhibitors , Cyclic AMP/genetics , Cyclic AMP Response Element-Binding Protein/genetics , Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors , Cyclic AMP-Dependent Protein Kinases/genetics , Disease Models, Animal , Femur/growth & development , Femur/pathology , Femur/radiation effects , Gene Expression Regulation/drug effects , Gene Expression Regulation/radiation effects , Humans , Osteoblasts/radiation effects , Osteoporosis/genetics , Osteoporosis/pathology , Rats , Signal Transduction/radiation effectsABSTRACT
Objective: To explore the enzymatic hydrolysis conditions of Xiaoyao-pill herb residues by cellulose. Methods: Based on the single factor test,an Box-Benhnken design was used to optimize the parameters, three factors, including cellulase dosage, enzymolysis time, and solid-liquid ratio were regarded as investigation factors,the yield of enzymatic hydrolysis as index, Xiaoyao-pill herb residues enzymatic hydrolysis catalyzed by cellulase, and a mathematical regression model was established. Results: The optimal parameters were obtained as follows,cellulase dosage was 6%,enzymolysis time was 5. 6 h and solid-liquid ratio was 1 ⶠ12( g / m L). Under this condition,the yield of enzymatic hydrolysis was 43. 89%. Conclusion: The results may provide new reference for further exploring Chinese herbal medicine efficiently.