Objective To investigate the effect of dexmedetomidine(Dex)on bone loss in tail-suspended rats and primarily explore its regulatory mechanism on bone metabolism.Methods A total of 30 male rats were randomly divided into a control group,a model group,and a Dex group,with 10 animals in each group.Rat model of osteoporosis was established by hind limb suspension for 4 weeks.Dex at a dose of 10 μg/kg was given intraperitoneally,once every other day from the day of tail suspension.And equal amount of normal saline was given to the control and model group.Bone histological staining was used to observe the trabecular bone area fraction.Biomechanical three-point bending test was employed to measure the maximum load,stiffness,and fracture energy.Dual calcein/alizarin red fluorescence labeling and tartrate resistant acid phosphatase(TRAP)staining were applied respectively to detect the mineral apposition rate and bone formation rate as well as the number of osteoclasts on bone surfaces.Secondly,after primary osteoblasts were isolated from the tibiae of tail-suspended rats and then treated with 1 nmol/L Dex,the proportion of alkaline phosphatase(ALP)-positive osteoblasts and the activity of the enzyme were detected by ALP staining and activity test.qRT-PCR was applied to measure the expression of osteogenic activity-related factors,including osteocalcin(Ocn),Runt related transcription factor 2(Runx2),Osterix protein(Osx),and type 1 collagen(Col1).Results The animal experiments revealed that Dex treatment significantly increased the tibial trabecular bone area fraction,inhibited the decrease in bone mechanical strength,and enhanced the mineralization deposition rate and new bone formation rate of trabecular bone in the tail-suspended rats(all P＜0.001).The in vitro experiments showed that Dex treatment obviously improved ALP activity and the number of ALP-positive osteoblasts in primary osteoblasts isolated from tail-suspended rats(P＜0.01),and up-regulated the expression levels of osteogenic differentiation-related genes,such as Ocn,Runx2,Osx and Col1(P＜0.01).Conclusion Dex exerts anti-bone loss effect in tail-suspended rats,which may be associated with its stimulation on osteoblast-mediated bone formation.

Objective:To investigate the effects of pulsed electromagnetic field(PEMF)on sevoflurane-induced cognitive dysfunction in elderly rats and also explore its related mechanism.Methods:Thirty elderly male rats were randomly divided into the control group,sevoflurane treatment group(SEV),and sevoflurane+PEMF treatment group(SEV+PEMF).Rats in the sevoflurane group and sevoflurane+PEMF group passively inhaled 2.5％sevoflurane for 4 h,while rats in the SEV+PEMF group were stimulated with 2 mT,15 Hz PEMF for 14 d(2 h/day).The cognitive function of rats was evaluated via the Morris water maze testing.The serum concentrations of tumor necrosis factor-α(TNF-α),interleukin-1 β(IL-1β),IL-6,neuron specific enolase(NSE),and β amyloid protein(Aβ),as well as the levels of nerve growth factor(NGF)and brain-derived neurotrophic factor(BDNF)in hippocampal tissue,were de-termined via ELISA.Western blot was used to detect the expression of autophagy-related biomarkers in rat hippocampal tissue.Secondly,30 elderly male rats were randomly divided into three groups:SEV group,SEV+PEMF group,and SEV+3-MA(the autophagy inhibitor)+PEMF group.The Morris water maze experiment was used to evaluate the change of PEMF-induced improvement of cognitive function sevoflurane-inhaled elderly rats following the autophagy inhi-bition.Results:PEMF inhibited sevoflurane-induced increase in escape latency and overall swimming distance,as well as the decrease in the number of crossing target quadrant(P＜0.05);PEMF decreased the levels of serum Aβ and NSE in elderly rats inhaled with sevoflurane(P＜0.05),decreased the levels of TNF-α,IL-1β,and IL-6(P＜0.05),increased the levels of NGF and BDNF in hippocampal tissue(P＜0.05),inhibited neuronal apoptosis in hip-pocampal tissue and increased its autophagy level(P＜0.05).Following inhibition of autophagy with 3-MA,the im-provement of PEMF on the decreased learning and memory ability induced by sevoflurane in elderly rats was significantly inhibited(P＜0.05).Conclusion:PEMF can effectively inhibit sevoflurane-induced cognitive dysfunction in elderly rats by regulating the autophagy of hippocampal neuronal cells.

Objective:To synthesize hydroxyapatite/poly (lactic-co-glycolic acid)(HA/PLGA) composites by substituting calcium ions in HA with Cu and Gd ions, characterize their physicochemical properties, and evaluate their feasibility for orbital bone defect repair.Methods:Different ratios of Cu-, Gd-, and Cu/Gd-substituted HA nanoparticles (Cu@HA, Gd@HA and Cu/Gd@HA) were synthesized via hydrothermal synthesis using copper nitrate, gadolinium nitrate, calcium chloride, and ammonium hydrogen phosphate.HA/PLGA, Cu@HA/PLGA, Gd@HA/PLGA, and Cu/Gd@HA/PLGA composites were prepared.HA/PLGA was prepared by co-preparing different ratios of nanoparticles with PLGA via phase inversion and solvent evaporation.The nanoparticles and composites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), environmental scanning electron microscope (ESEM) and micro-computed tomography (Micro-CT). Composite homogeneity was assessed by elemental analysis and the contact angle was measured to evaluate hydrophilicity.Imaging capability of composites was assessed by magnetic resonance imaging (MRI) and T1-weighted.CCK-8 method was used to detect the cytotoxicity of nanoparticles and their extract.Orbital bone defects model was established in 20 rats, which were randomly divided into 4 groups, and implanted with respective composites.Eight weeks after transplantation, the implants were evaluated using Micro-CT and MRI, and osteogenesis, collagen distribution and biocompatibility were assessed by hematoxylin-eosin staining, Masson, and Sirius red staining.All animal experiments complied with the regulations of the Laboratory Animal Ethics Committee of Dalian Medical University and were approved (No.AEE23104).Results:XRD and ESEM results showed that co-doping with Cu/Gd induced less HA lattice distortion than single doping.FT-IR results showed that the nanoparticles doped with Cu and Gd ions were consistent with the HA infrared absorption spectrum.ICP results revealed a higher Ca content in 0.5Cu/Gd@HA and 0.5Cu@HA samples than in 0.5Gd@HA sample.There was a statistically significant overall difference in contact angles among different groups of composites ( F=5.040, P<0.05), among which the 0.5Cu/Gd@HA/PLGA composite exhibited the smallest contact angle and the best hydrophilicity.There was no statistically significant difference in porosity among different groups of composites ( F=0.004, P>0.05). MRI results showed that Gd-doped composites displayed enhanced development and that the signal intensity of the 0.5Gd@HA/PLGA group was the highest.Micro-CT scanning results showed that the composition of the composite material doped with Cu and Gd was better than that of the pure HA/PLGA group, indicating that the metal ions Cu and Gd could promote bone growth.CCK-8 results showed that the nanoparticles and their extracts had no obvious cytotoxic effects.Eight weeks after modelling, Micro-CT showed that the 0.5Cu/Gd@HA/PLGA material degraded well in vivo and the staining results of bone tissue sections in the bone defect area suggested that tissues around the implanted material and rat organs in different groups did not show biological toxicity.In addition, the Gd-doped composites showed good magnetic imaging characteristics when implanted in animals. Conclusions:Cu/Gd@HA/PLGA composites exhibit favorable physicochemical properties, biosafety, osteogenic potential, and MRI contrast and have good clinical application prospects for orbital bone repair.

Objective:To synthesize hydroxyapatite/poly (lactic-co-glycolic acid)(HA/PLGA) composites by substituting calcium ions in HA with Cu and Gd ions, characterize their physicochemical properties, and evaluate their feasibility for orbital bone defect repair.Methods:Different ratios of Cu-, Gd-, and Cu/Gd-substituted HA nanoparticles (Cu@HA, Gd@HA and Cu/Gd@HA) were synthesized via hydrothermal synthesis using copper nitrate, gadolinium nitrate, calcium chloride, and ammonium hydrogen phosphate.HA/PLGA, Cu@HA/PLGA, Gd@HA/PLGA, and Cu/Gd@HA/PLGA composites were prepared.HA/PLGA was prepared by co-preparing different ratios of nanoparticles with PLGA via phase inversion and solvent evaporation.The nanoparticles and composites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), environmental scanning electron microscope (ESEM) and micro-computed tomography (Micro-CT). Composite homogeneity was assessed by elemental analysis and the contact angle was measured to evaluate hydrophilicity.Imaging capability of composites was assessed by magnetic resonance imaging (MRI) and T1-weighted.CCK-8 method was used to detect the cytotoxicity of nanoparticles and their extract.Orbital bone defects model was established in 20 rats, which were randomly divided into 4 groups, and implanted with respective composites.Eight weeks after transplantation, the implants were evaluated using Micro-CT and MRI, and osteogenesis, collagen distribution and biocompatibility were assessed by hematoxylin-eosin staining, Masson, and Sirius red staining.All animal experiments complied with the regulations of the Laboratory Animal Ethics Committee of Dalian Medical University and were approved (No.AEE23104).Results:XRD and ESEM results showed that co-doping with Cu/Gd induced less HA lattice distortion than single doping.FT-IR results showed that the nanoparticles doped with Cu and Gd ions were consistent with the HA infrared absorption spectrum.ICP results revealed a higher Ca content in 0.5Cu/Gd@HA and 0.5Cu@HA samples than in 0.5Gd@HA sample.There was a statistically significant overall difference in contact angles among different groups of composites ( F=5.040, P<0.05), among which the 0.5Cu/Gd@HA/PLGA composite exhibited the smallest contact angle and the best hydrophilicity.There was no statistically significant difference in porosity among different groups of composites ( F=0.004, P>0.05). MRI results showed that Gd-doped composites displayed enhanced development and that the signal intensity of the 0.5Gd@HA/PLGA group was the highest.Micro-CT scanning results showed that the composition of the composite material doped with Cu and Gd was better than that of the pure HA/PLGA group, indicating that the metal ions Cu and Gd could promote bone growth.CCK-8 results showed that the nanoparticles and their extracts had no obvious cytotoxic effects.Eight weeks after modelling, Micro-CT showed that the 0.5Cu/Gd@HA/PLGA material degraded well in vivo and the staining results of bone tissue sections in the bone defect area suggested that tissues around the implanted material and rat organs in different groups did not show biological toxicity.In addition, the Gd-doped composites showed good magnetic imaging characteristics when implanted in animals. Conclusions:Cu/Gd@HA/PLGA composites exhibit favorable physicochemical properties, biosafety, osteogenic potential, and MRI contrast and have good clinical application prospects for orbital bone repair.

Objective:To investigate the effects of pulsed electromagnetic field(PEMF)on sevoflurane-induced cognitive dysfunction in elderly rats and also explore its related mechanism.Methods:Thirty elderly male rats were randomly divided into the control group,sevoflurane treatment group(SEV),and sevoflurane+PEMF treatment group(SEV+PEMF).Rats in the sevoflurane group and sevoflurane+PEMF group passively inhaled 2.5％sevoflurane for 4 h,while rats in the SEV+PEMF group were stimulated with 2 mT,15 Hz PEMF for 14 d(2 h/day).The cognitive function of rats was evaluated via the Morris water maze testing.The serum concentrations of tumor necrosis factor-α(TNF-α),interleukin-1 β(IL-1β),IL-6,neuron specific enolase(NSE),and β amyloid protein(Aβ),as well as the levels of nerve growth factor(NGF)and brain-derived neurotrophic factor(BDNF)in hippocampal tissue,were de-termined via ELISA.Western blot was used to detect the expression of autophagy-related biomarkers in rat hippocampal tissue.Secondly,30 elderly male rats were randomly divided into three groups:SEV group,SEV+PEMF group,and SEV+3-MA(the autophagy inhibitor)+PEMF group.The Morris water maze experiment was used to evaluate the change of PEMF-induced improvement of cognitive function sevoflurane-inhaled elderly rats following the autophagy inhi-bition.Results:PEMF inhibited sevoflurane-induced increase in escape latency and overall swimming distance,as well as the decrease in the number of crossing target quadrant(P＜0.05);PEMF decreased the levels of serum Aβ and NSE in elderly rats inhaled with sevoflurane(P＜0.05),decreased the levels of TNF-α,IL-1β,and IL-6(P＜0.05),increased the levels of NGF and BDNF in hippocampal tissue(P＜0.05),inhibited neuronal apoptosis in hip-pocampal tissue and increased its autophagy level(P＜0.05).Following inhibition of autophagy with 3-MA,the im-provement of PEMF on the decreased learning and memory ability induced by sevoflurane in elderly rats was significantly inhibited(P＜0.05).Conclusion:PEMF can effectively inhibit sevoflurane-induced cognitive dysfunction in elderly rats by regulating the autophagy of hippocampal neuronal cells.

Objective To delineate the expressions of ubiquitin-specific proteinase 49 (USP49)and FK506 binding protein 51 (FKBP51) in the spinal dorsal horns and their roles in rats with diabetic neuropathic pain (DNP).Methods Male SD rats were fed with high glucose and high fat diet with an intraperitoneal injection of 1％ streptozocin to establish DNP rat models.DNP rats were allocated into DNP group,control shRNA group (KC group) and knockdown USP49 group (KD group,n=10);saline,Ad-scrambled shRNA (3×108 PFU/mL) and Ad-USP49-shRNA (3×108 PFU/mL) were intrathecally injected into the rats of the three groups.Another 10 normal rats were chosen as control group (C group).Thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) were measured one d before model establishment,one and 7 d after model establishment,one,three and 7 d after intrathecal injection.The mRNA and protein expressions of USP49,FKBP51 and glucocorticoid receptor α (GRα)in dorsal horn neurons were detected by real time-PCR and Western blotting.Results (1) TWL showed no significant difference among the four groups one d before model establishment (P＞0.05);three and 7 d after intrathecal injection,TWL in KD group was significantly prolonged as compared with that in the DNP group,and significantly shortened as compared with that in C group (P＜0.05).(2) MWT showed no significant difference among the four groups one d before model establishment (P＞0.05);three and 7 d after intrathecal injection,MWT in KD group was significantly higher as compared with that in the DNP group,and significantly lower as compared with that in C group (P＜0.05).(3) As compared with DNP group,KD group had significantly decreased mRNA expressions of USP49 and FKBP51,and statistically increased mRNA GRα expression (P＜0.05).(4) As compared with DNP group,KD group had significantly decreased protein expressions of USP49 and FKBP51,and statistically increased protein GRα expression (P＜0.05).Conclusion Specific knockdown of USP49 expression is associated with improvement of heat hyperalgesia and mechanical hyperalgesia in DNP rats,which may be attributed to the de-ubiquitination ofFKBP51 by USP49.