The Protective Effects Of Phycocyanin On Cerebral Ischemia Reperfusion In Rats

Objective: To study the expressions of nuclear factor k B (NF- k B), interleukin-6 (IL-6) and to observe the possible protective mechamism of phycocyanin on the focal cerebral ischemia reperftision in rats.Methods: 60 adult male rats, weight of 220~260g. The model of middle cerebral artery occlusion and reperfusion(MCAO/R) in Wistar rats was performed with the intraluminal filament occlusion, which were divided into the sham-operated group, controlled group (saline solution was perfused into stomach) and the phycocyanin group (phycocyanin was perfused into stomach). Each group was divided into severn subgroups at reperfusion 6h 12h 1d 2d 3d 7d, 14d, which consisted of 4 rats. Distributions and quantities of NF-kB, IL-6 and the apoptosis of the neurons in the rat brain tissue was shown by immunohistochemical staining method. Neuronal apoptosis was detected by TdT-mediated dUTP nick and labeling (TUNEL) assay.Results: I.NF-kB: The expression of NF-k B occurred at 6h, peaked at Id, maintained 24h-72h after reperfusion and decreased gradually to the sham group level at 14d.The level of NF-k B in cerebral cortex was concordant with that in striatum.Compared with the controlled group, the use of phycocyanin could reduce the level of NF- k B. There was significant difference between the two groups (P<0.01 ).2.IL-6: The change of the expression of IL-6 protein is similar to that of NF- k B, but the peak occurred at 2d after reperfusion and decreased slowly. Up to the reperfusion 14d, it dropped to the baseline in brain tissue. The expression of IL-6 in cerebral cortex was concordant with that in striatum.Compared with the controlled group,perfusing phycocyanin could regulate down the level of IL-6 significantly (P<0.01).3.The related analysis of the expression of NF- k b and IL-6: The level of NF- k B expression reached the peak earlier than lL-6.The level of NF- k B and IL-6 expressesion increased gradually during reperfusion 6h,12h,ld. The increase of the two factors is positively(p<0.01).The level of the two factors expressesion descended gradually during reperfusion 2d,7d,14d. The descent of the two factors is positively(p<0.01).4.TUNEL cell: Apoptosis neurons were seen under TUNEL staining. To observe the morphologic feature of apoptosis neurons under micoscope, the nucleic shrank, apoptotic bodies could be seen. The change of TUNEL cells in cerebral cortex was essentially concordant with that in striatum.The number of apoptosis cells was increased at 6h in cerebral cortex and in striatum, but reached the peak on Id in cerebral cortex, 2d in striatum, and decreased gradually to the baseline in brain tissue at 14d. Compared with the controlled group, the use of phycocyanin could reduce the number of apoptosis cells significantly (P<0.01).Conclusions: NF- k B and IL-6 may play an important role in ischemia reperfusion injury. The neuroprotective effect of phycocyanin may relate to the down regulation of NF- k B IL-6, to antiinfiammation and antiapoptosis.