Low-frequency pulsed electromagnetic fields promote osteoblast mineralization and maturation of rats through the PC2/sAC/PKA/CREB signaling pathway / 南方医科大学学报

OBJECTIVE@#To explore whether the effect of low-frequency pulsed electromagnetic fields (PEMFs) in promoting osteoblast mineralization and maturation is related to the primary cilia, polycystin2 (PC2) and sAC/PKA/CREB signaling pathway.@*METHODS@#We detected the expression levels of PC2, sAC, PKA, CREB and their phosphorylated proteins in primary rat calvarial osteoblasts exposed to 50 Hz 0.6 mT PEMFs for 0, 5, 15, 30, 60, 90, and 120 min. We blocked PC2 function with amiloride hydrochloride and detected the changes in the activity of sAC/PKA/CREB signal pathway and the mineralization and maturation of the osteoblasts. These examinations were repeated in the osteoblasts after specific knockdown of PC2 via RNA interference and were the co-localization of PC2, sAC, PKA, CREB and their phosphorylated proteins with the primary cilia were using immunofluorescence staining. The expressions of PC2 and the signaling proteins of sAC/PKA/CREB pathway were detected after inhibition of primary ciliation by RNA interference.@*RESULTS@#The expression levels of PC2, sAC, p-PKA and p- CREB were significantly increased in the osteoblasts after exposure to PEMFs for different time lengths (P < 0.01). Blocking PC2 function or PC2 knockdown in the osteoblasts resulted in failure of sAC/PKA/CREB signaling pathway activation and arrest of osteoblast mineralization and maturation. PC2, sAC, p-PKA and p-CREB were localized to the entire primary cilia or its roots, but PKA and CREB were not detected in the primary cilia. After interference of the primary cilia, PEMFs exposure no longer caused increase of PC2 expression and failed to activate the sAC/PKA/CREB signaling pathway or promote osteoblast mineralization and maturation.@*CONCLUSION@#PC2, located on the surface of the primary cilia of osteoblasts, can perceive and transmit the physical signals from PEMFs and promote the mineralization and maturation of osteoblasts by activating the PC2/ sAC/PKA/CREB signaling pathway.

Effect of polycystin2 on differentiation and maturation of osteoblasts promoted by low-frequency pulsed electromagnetic fields / 生物工程学报

It is known that low-frequency pulsed electromagnetic fields (PEMFs) can promote the differentiation and maturation of rat calvarial osteoblasts (ROBs) cultured in vitro. However, the mechanism that how ROBs perceive the physical signals of PEMFs and initiate osteogenic differentiation remains unknown. In this study, we investigated the relationship between the promotion of osteogenic differentiation of ROBs by 0.6 mT 50 Hz PEMFs and the presence of polycystin2 (PC2) located on the primary cilia on the surface of ROBs. First, immunofluorescence staining was used to study whether PC2 is located in the primary cilia of ROBs, and then the changes of PC2 protein expression in ROBs upon treatment with PEMFs for different time were detected by Western blotting. Subsequently, we detected the expression of PC2 protein by Western blotting and the effect of PEMFs on the activity of alkaline phosphatase (ALP), as well as the expression of Runx-2, Bmp-2, Col-1 and Osx proteins and genes related to bone formation after pretreating ROBs with amiloride HCl (AMI), a PC2 blocker. Moreover, we detected the expression of genes related to bone formation after inhibiting the expression of PC2 in ROBs using RNA interference. The results showed that PC2 was localized on the primary cilia of ROBs, and PEMFs treatment increased the expression of PC2 protein. When PC2 was blocked by AMI, PEMFs could no longer increase PC2 protein expression and ALP activity, and the promotion effect of PEMFs on osteogenic related protein and gene expression was also offset. After inhibiting the expression of PC2 using RNA interference, PEMFs can no longer increase the expression of genes related to bone formation. The results showed that PC2, located on the surface of primary cilia of osteoblasts, plays an indispensable role in perceiving and transmitting the physical signals from PEMFs, and the promotion of osteogenic differentiation of ROBs by PEMFs depends on the existence of PC2. This study may help to elucidate the mechanism underlying the promotion of bone formation and osteoporosis treatment in low-frequency PEMFs.

Effects of low frequency pulsed electromagnetic field on stomach blood circulation and ultra microstructure of stress ulcer in rats / 医疗卫生装备

Objective To determine non-thermal biological effect of low frequency pulsed electromagnetic field (LFPEF)on the stomach blood circulation and ultra microstructure of rat stress ulcer. Methods Thirty-six Sprague-Dawley rats were assigned to three equal groups:control,ulcer without interference group(UW)and ulcer exposure groups(UE).The rats stress ulcer models were constructed with the combination method of soak and bind in the low-pressure and hypoxia circumstance. Based on the singlechip,a LFPEF generator with adjustable frequency, amplitude and duty ratio was developed. Then the stomachs of the rats were exposed to the LFPEF generator 3 hours per day.On days 1,3,5 and 7,the blood circulation of the stomach was analyzed by the content of the serum NO and contrast ultrasonography.In addition,the ulcer tissue was taken out for section-staining. Finally, the pathological change of the stomach ultra microstructure was observed under a light microscope. Results On different days, the contents of the serum NO and microbubble concentration of UE group were significantly higher than those of the UW group(P<0.05). The pathological observation showed that the restoration of the gastric tissue in UE group was faster than that in the UW group(P<0.05).Conclusion LFPEF with certain proper parameter could improve the gastric tissue blood circulation and accelerate the stress ulcer restoration. [Chinese Medical Equipment Journal,2018,39(5):35-38]

Study the protective effects of low-frequency pulsed electromagnetic field on neuron following cerebral ischemia-reperfusion injury in rats / 临床神经病学杂志

Objective To investigate the protective effects of low-frequency pulsed electromagnetic field (LFPMF) on neuron following cerebral ischemia-reperfusion injury in rats.Methods 24 adult male Sprague-Dawley rats were randomly divided into irradiation group (n=12) and control group (n=12). The global cerebral ischemia-reperfusion models of rats were produced by modified Pulsineli method. Rats in irradiation group were exposed to 20 mT intensity LFPMF of 10 Hz for 45 minutes per day for 4 days. The electroencephalogram (EEG) was recorded by powerlab system. Nissl staining was used to perform quantitative analysis of neuron number and immunohistochemistry staining provided the information of the distribution of positive cells to caspase-3.Results Compared with the control group, the amplitude of EEG was significantly higher in irradiation group [(10.27?1.12)?V versus (8.95?1.04)?V] (P