ABSTRACT
5-HT as an important neurotransmitter which takes part in the development of many diseases, including bronchial asthma,schizophrenia and bone metabolism as reported in literatures in recent years. Central 5-HT can inhibit sympathetic excitations and promote bone formation through Tph2. Lrp5 can reduce the level of peripheral 5-HT and act on Tph1 to promote bone formation. Peripheral 5-HT blocks the association between transcription factor FOXO1 and CREB and inhibits bone formation. Peripheral 5-HT can also promote IL-6 expression and induce bone reabsorption. LP533401 as a Tph1 inhibitor could effectively reduce the level of peripheral 5-HT and induce bone formation as reported. In this paper, we try to summarize the effect of 5-HT on bone metabolism and its mechanism, and further using 5-HT to regulate bone quantity effectively.
ABSTRACT
Objective The relationship between osteoblast autophagy induced by wear particles and secretion of inflammatory cytokines has not been illuminated.The purpose of this study was to investigate the effect of wear particles on the secretion of TNF -α and IL-6 by autophagy of osteoblasts in aseptic loosening. Methods The mouse MC3T3-E1 osteoblasts in logarithmic growth phase were divided into 5 groups:control group(in α-MEM medium),CoCrMo particle group(100 μg/mL CoCrMo particles was added in α-MEM medium),3-MA group(10 mmol/L autophagy inhibitor 3-MA prestimulated osteoblasts in α-MEM medium,3h later 100 μg/mL CoCrMo particles were added),the expression of autophagy marker protein LC-3 in osteoblasts was detected by Western blotting, and the levels of TNF-αand IL-6 were detected by ELISA. Results Compared with the control group,the expression level of auto-phagy marker protein LC-3 was significantly increased in CoCrMo particles group(P<0.05).Compared with CoCrMo particles group,the expression level of LC-3 in 3-MA group was significantly decreased(P<0.05).Compared with control group TNF-α[(0.95± 0.00)pg/mL]and IL-6[(4.67±0.23)pg/mL], CoCrMo particles group TNF-α[(10.35±3.63)pg/mL]and IL-6[(14.27±1.07)pg/mL]secretion level was significantly increased(P<0.05),compared with CoCrMo particles group,the effects of 10 mmol/L 3-MA group to TNF-α[(13.13±5.08)(14.71±5.46)pg/mL]and IL-6[(15.31±0.88),(16.75±3.87)pg/mL]secretion were not significant, while 10 mmol/L 3-MA group TNF-α[The secretion levels of(302.61±45.63)pg/mL]and IL-6[(216.67±27.71)pg/mL]in-creased significantly(P<0.01). Conclusion The osteoblast autophagy induced by CoCrMo particles can inhibit the secretion of in -flammatory cytokines TNF-αand IL-6 in osteoblasts.