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Objective·To detect the effects of propofol sedation on cognitive function in rats and its mechanism. Methods?·?Forty-eight SD rats were randomly divided into three groups, i.e. control group, 100?mg/kg group and 300?mg/kg group. Rats were administrated intraperitoneally with propofol (10?mg/mL, 100?mg/kg or 300?mg/kg). The mRNA levels of brain derived neurotropic factor (BDNF)-TrkB/p75 signal molecules in rat hippocampus were evaluated by realtime PCR 45 min after propofol treatment. Learning and memory ability was examined by inhibitory avoidance (IA) test after propofol treatment. Results?·?The mRNA levels of BDNF in the hippocampal tissue were (1.20±0.13) fold (P=0.002) and (88±12) % (P=0.044) of that in control group, respectively, in 100?mg/kg group and 300?mg/kg group after injection of propofol. The mRNA levels of TrkB were (1.01±0.11) fold ( P=0.982) and (86±11) % (P=0.018) of that in control group, respectively, in 100?mg/kg group and 300?mg/kg group. The mRNA levels of p75 were (1.02±0.10) fold (P=0.778) and (1.59±0.18) fold (P=0.000) of that in control group, respectively, in 100?mg/kg group and 300?mg/kg group. There was no significant difference of the 24 h IA memory retention latency between 100?mg/kg group and control group. The 24 h IA memory retention latency in 300?mg/kg group was significantly decreased compared with control group (P=0.028) and 100?mg/kg group (P=0.020). Conclusion?·?Propofol dose-dependently regulates the expression of BDNF-TrkB/p75 signal molecules, and high dose propofol may reduce cognitive function via BDNF-TrkB/p75 signal.
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Objective·To detect the effects of propofol on rat hippocampal astrocytes and clarify its mechanism.Methods·According to the time after propofol injection,twenty-four SD rats were randomly divided into three groups,i.e.0 min,45 min and 90 min group.Rats were administrated intraperitoneally with propofol (10 mg/mL,100 mg/kg body weight).The levels of glial fibrillary acidic protein (GFAP) and S100β mRNA in rat hippocampus were evaluated by realtime PCR.And cell viabilities and levels of GFAP mRNA were examined in primary cultured hippocampal astrocytes induced by 10 μmol/L propofol with or without 10 μmol/L extracellular signal-regulated kinase (ERK) inhibitor PD98059 pretreatment.Results·The mRNA levels of GFAP in the hippocampal tissue were (1.32±0.12) times (P=0.000) and (1.12±0.09) times (P=0.012) that in 0 min group,respectively,45 min and 90 min after injection of propofol.The mRNA levels of S100β in the hippocampal tissue were (1.14±0.11) times (P=0.005) and (1.05±0.10)times (P=0.284) that in 0 min group,respectively,45 min and 90 min after injection of propofol.The mRNA levels of GFAP and S100β were timedependently altered,first increasing,and then decreasing.In vitro,the cell viabilities (P=0.041) and levels of GFAP mRNA (P=0.026) in primary cultured hippocampal astrocytes were significantly elevated after propofol treatment,and these effects of propofol were reversed by ERK inhibitor PD98059.Conclusion·Propofol time-dependently upregulated the expression of GFAP and S100β via ERK signaling pathway in rat hippocampal astrocytes,so as to activate astrocytes.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the biomechanical effect of anterior screw fixation on the type II fractured odontoid process.</p><p><b>METHODS</b>Twenty fresh human C1-C2 vertebrae specimens were harvested and randomly divided into three groups. The angle of type II fracture line was 0 degree in group I (n=6), 17 degrees in group II (n=8) and 25 degrees in group III (n=6). The fractures were treated by anterior screw fixation. Insertion torque,maximal axial pullout force and stiffness of the bone-screw were tested.</p><p><b>RESULTS</b>There was no significant difference of screw insertion torque and the pull-out strength between each group. The displacement of the odontoid fragment had an association to the angle of the fracture line,the displacement of the small angle was significantly higher than that of the large one (P < 0.5). No significant difference of structure stiffness of the bone-screw was found between each group.</p><p><b>CONCLUSION</b>Anterior screw fixation is feasible for type II odontoid fracture with certain fracture line extends from anteroinferior to posterosuperior.</p>