ABSTRACT
Objective To evaluate the effects of leptin on brain injury and long-term cognitive function in rats undergoing orthotopic liver transplantation. Methods Ninety clean-grade male Sprague-Dawley rats, aged 3 months, weighing 200-250 g, were divided into 3 groups by a random number table method: sham operation group ( S group) , liver ischemia-reperfusion ( I∕R) group ( I∕R group) and lep-tin group ( L group) , with 18 rats in each group. Orthotopic liver transplantation was performed to estab-lish the model of liver I∕R injury in I∕R and L groups. Leptin 1 mg∕kg was intraperitoneally injected at the onset of ischemia in L group, and the equal volume of normal saline was given instead of leptin in S and I∕R groups. Twelve rats in each group were sacrificed at 3 days after operation, and brains were removed for ex-amination of the pathological changes in hippocampal CA1 region ( with a light microscope) and for determi-nation of apoptosis in hippocampal neurons ( by TUNEL assay) and expression of aquaporin 4 ( AQP4) and protein kinase C ( PKC) in the hippocampus ( by Western blot) . The apoptosis rate was calculated. The remaining 6 rats in each group underwent a Morris water maze test at 30 days after surgery to evaluate long-term cognitive function. Results Compared with S group, the apoptosis rate of hippocampal neurons was significantly increased, the expression of AQP4 and PKC was up-regulated, the escape latency was pro-longed, and the time of staying at the platform quadrant was shortened in I∕R and L groups (P<0. 05). Compared with I∕R group, the apoptosis rate of hippocampal neurons was significantly decreased, the ex-pression of AQP4 and PKC was down-regulated, the escape latency was shortened, and the time of staying at the platform quadrant was prolonged in L group (P<0. 05). Conclusion Leptin can reduce the brain damage in rats undergoing orthotopic liver transplantation, the mechanism may be related to down-regulating the expression of PKC and AQP4, and leptin can also improve long-term cognitive function after orthotopic liver transplantation in rats.
ABSTRACT
Objective To investigate the effects of dexmedetomidine pre-treatment on pneumonocyte apoptosis and CCAAT/enhancer binding protein homologous protein (CHOP) in acute lung injury (ALI) induced by ischemia/reperfusion (I/R) during orthotopic liver transplantation in rats.Methods Forty adult male Sprague-Dawley (SD) rats were randomly divided into four groups by random number table method: sham operation group, I/R model group, dexmedetomidine low dose group and dexmedetomidine high dose group, 10 rats per group. Hepatic artery was ligated and cut off by two cuff method, and the portal vein was completely opened after donor liver transplanted into the recipient, thus, a hepatic I/R model was established. The perihepatic ligaments of rats were just separated after laparotomy in sham operation group and no other special treatment was performed. One hour prior to I/R, dexmedetomidine at a dose of 2.5μg·kg-1·h-1 and 5.0μg·kg-1·h-1, respectively, were pumped intravenously and finished within 1 hour in the rats of low dose group and high dose group. After experiment, the lung tissue was taken, and the lung wet/dry weight (W/D) ratio was determined. Pathological changes of lung tissue were observed and alveolar damage index of quantitative assessment (IQA) was tested by light microscope, and changes of ultrastructure of lung tissue were observed by transmission electron microscope. The mRNA and protein expressions of CHOP were detected respectively by reverse transcription-polymerase chain reaction (RT-PCR) and Western Blot. The apoptosis in lung tissue was determined by terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) method and apoptosis index (AI) was calculated.Results Compared to sham operation group, the lung W/D ratio (4.94±0.84 vs. 2.29±0.54), IQA [(40.52±5.15)% vs. (4.55±1.85)%] and AI [(36.57±5.85)% vs. (2.85±0.95)%] in I/R model group were significantly higher (allP < 0.01); remarkable injury of lung tissue was confirmed by light microscope and transmission electron microscope in the I/R model group. Compared to I/R model group, the W/D ratio (3.29±0.85, 2.68±0.78 vs. 4.94±0.84), IQA [(23.69±2.62)%, (15.86±3.61)% vs. (40.52±5.15)%] and AI [(25.73±3.71)%, (14.66±2.61)% vs. (36.57±5.85)%] in dexmedetomidine low and high dose groups were markedly lower (allP < 0.01); under light and transmission electron microscopes, the injury of lung tissue in these two dose groups was notably alleviated. There was a large amount of apoptotic cells of pulmonary vascular endothelium and alveolar epithelium in I/R model group, while the cell apoptosis was distinctly decreased in dexmedetomidine low and high dose groups compared to that in model group. Compared to sham operation group, the expressions of CHOP mRNA [absorbance (A) value: 0.96±0.18 vs. 0.43±0.08] and protein (gray scale: 2.79±0.74 vs. 1.02±0.27) were significantly higher in I/R model group (bothP < 0.01). Compared to I/R model group, the expressions of CHOP mRNA (A value: 0.69±0.13, 0.56±0.12 vs. 0.96±0.18) and protein (gray scale: 1.96±0.58, 1.34±0.49 vs. 2.79±0.74) were significantly lower in dexmedetomidine low and high dose groups, the decrease in dexmedetomidine high dose group being more marked (allP < 0.01).Conclusion The pretreatment of dexmedetomidine can protect lung tissue against I/R injury during liver transplantation in rats, and the mechanism may be related to the suppression of CHOP activation and alleviation of lung tissue cell apoptosis.