| Objective: To investigate the neuroprotective effect of piperine on acute ischemic brain injury in rats.Methods: 32 male SD rats, weighing between 280g~320g, were randomly divided into four groups(n=8) including shamed group, saline group, vehicle group (vehicle is a kind of mixtured solution of sterilized distilled water, ethanol and Polyglycol-400) and piperine group. The MCAO model in saline group, vehicle group, piperine group was established with suture occlusion technique according to modified Zea Longa method. The model in shamed group was the same to MCAO model excepting the insert length of suture (<10mm). All rats were administrated with saline(7ml/kg) for those in shamed group and saline group, vehicle(7ml/kg) for vehicle group and piperine(20mg/kg) for piperine group by intragastric administration at half an hour, 24h and 48h after operation of MCAO, respectively. The neurologic impairment was evaluated at 2h, 24h ,48h and 72h after operation of MCAO according to Zea Longa. All of the rats were killed at 72h after MCAO. The brains were removed and then coronally sectioned into 2-mm coronal slices. The infarct volumes were calculated by TTC staining. Another 32 male SD rats were treated as same as it described above. All of the animal were perfused with 4% paraformaldehyde in 0.1 mol/L phosphate buffer at 24h after MCAO. The brains were removed from the skull, postfixed 24 hours in the same fixative and then sectioned into 2-mm coronal slice anterior to optic chiasma. After paraffin embedding, the consecutive sections were used to detected apoptosis by TUNEL method and expression of caspase-3 by immunohistochemistry technology in the penumbra region. The data was described with mean±standard deviation ( X±S). Multiple comparisons of the data were analyzed by multi-sample One-Way ANOVA and SNK-q test. It was taken as the significant difference when P<0.05.Results:1. Neurologic defect appeared in the saline ,vehicle and piperine group rat after MCAO. There was no neurologic impairment in the shamed group. There was no significant difference at 2h after MCAO among three of the saline ,vehicle and piperine group (p﹥0.05). The Neurological deficit scores of piperine group was significant improved compared with it of saline and vehicle group at 24h, 48h and 72h after MCAO(p﹤0.05).2. There was no infarct in shamed group. The infarcted volumes were (209.62±23.25)mm3 in saline group, (216.35±19.18)mm3 in vehicle group, (175.16±15.43)mm3 in piperine group. There was no significant difference between the saline group and vehicle group (p﹥0.05). it was found that obvious difference of infarcted volumes between piperine group and saline group or vehicle group(p﹤0.01).3.The count of apoptosis cells in saline group, vehicle group and piperine group were 52.70±6.15, 48.58±7.17 and 20.30±2.67, respectively. The apoptosis cells decreased dramatically in piperine group(p﹤0.01).4. The count of Caspase-3 postive cells were 21.30±3.20, 22.15±2.57 and 11.68±1.96 in saline group, vehicle group and piperine group respectively. There was no significant difference between the saline group and vehicle group (p﹥0.05). The Caspase-3 postive cells decreased dramatically in piperine group (p﹤0.01).Conclusion: 1. The piperine can decrease the Neurological deficit scores and reduce the infarcted volume. The piperine has the neuroprotective effect on acute ischemic brain injury in rats. 2. The piperine can inhibit the apoptosis of cells by reducing the expressing of caspase-3.
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