BACKGROUND: Phycocyanin can anti-oxidize and clear free radial. Whether its protective effect on brain is related to Caspase-3, the promoter and operator of apoptosis, is highly concerned. OBJECTIVE: To observe phycocyanin for protecting nerve function and reducing the size of cerebral infarction of rats with brain ischemia-reperfusion and its effect on the expression of Caspase-3 mRNA. DESIGN: A randomized controlled experiment. SETTING: Institute of Cerebrovascular Disease, Affiliated Hospital of Medical College of Qingdao University. MATERIALS: Totally 84 adult healthy female Wistar rats, weighing 210 to 250 g, of clean grade, were provided by the Animal Experimental Center of Shandong University. Phycocyanin (Institute of Oceanography of Chinese Academy of Sciences) was used. METHODS: This experiment was carried out in the Key Laboratory for Prevention and Treatment of Brain Diseases during May to December 2005.① The rats were randomized into sham-operation group (n=4), control group (n=40) and phycocyanin-treated group (n=40). Middle cerebral artery occlusion/reperfusion (MACO/R) models were created on the rats of control and phycocyanin-treated groups with suture-occluded method by inserting a thread into left side external-internal carotid artery. In the sham-operation group, inserting suture was omitted. After ischemia for 1 hour and reperfusion for 2 hours, suspension of phycocyanin was intragastrically administrated into the rats of the phycocyanin-treated group at 100 mg/kg , and the same volume of normal saline was isochronously administrated into the rats of control group as the same. ② Six rats were chosen respectively from the control group and phycocyanin-treated group, then neurologic impairment degrees of rats were evaluated according to Bederson’s grading. ③ Six rats were chosen respectively from the control and phycocyanin-treated groups. The isolated brain tissue was stained with triphenyltetrazolium chloride, and then the size of cerebral infarction was calculated with HPIAS-1000 image analytical system by calculating the ratio of cerebral infarction size at each layer and contralateral hemisphere size of the same layer. ④ Twenty-eight rats were chosen respectively from the control and phycocyanin-treated groups. Brain tissue was harvested at reperfusion for 6,12,24 hours and for 2,3,7 and 14 days after ischemia for 1 hour, respectively, 4 rats at each time point. Brain tissue of 4 rats of sham-operation group was harvested at the 24th hour after operation. Brain tissue sections were performed in situ hybridization detection of Caspase-3 mRNA. MAIN OUTCOME MEASURES: Comparison of neurologic impairment degree, cerebral infarction size and the expression of brain tissue Caspase-3 mRNA of rats between two groups. RESULTS: Totally 84 rats entered the stage of result analysis. ① Bederson’s scores at ischemia and reperfusion for 24 and 48 hours were significantly lower in the phycocyanin-treated group than in the control group(P < 0.05). ② After brain ischemia and reperfusion, the infarction area was the largest in the 3rd layer in both control and phycocyanin-treated group, which was(25.23±0.47)% and(23.09±1.20) %, respectively, and the size of infarction area in the 2nd layer to the 5th layer was significantly smaller in the phycocyanin-treated group than in the control group (P < 0.05). ③ Positive cell counts of brain tissue Caspase-3 mRNA: The number of positive cells of Caspase-3 mRNA of control group was increased from cerebral ischemia and reperfusion 6 hours, reached the peak at ischemia and reperfusion 24 hours, began to decrease 2 days later and positive cells of Caspase-3 mRNA were still expressed on the 14th day after reperfusion. At ischemia and reperfusion 6,12 and 24 hours as well as 2,3,7 and 14 days, positive cell counts of Caspase-3 at peripheral ischemic area were significantly lower in the phycocyanin-treated group[(70.67 ±3.65), (85.06±4.79), (119.54±5.37) ,(74.26±2.19), (62.08±3.34), (23.11±1.89), (10.75±2.63) /visual field] than in the control group[(94.38±8.28),(108.81±16.11),(140.88±14.47),(98.13±11.31),(81.03±9.31),(31.22±8.86), (16.06±5.96)/visual field] ( P < 0.05); and those at central ischemic area were also significantly lower in the phycocyanin-treated group [(33.86±4.01),(39.51±3.46),(50.96±2.53),(43.07±4.09),(36.25±3.72),(9.03±3.87),(4.91±5.59)/visual field ]than in the control group[(51.35±2.13),(54.87±3.42),(61.77±4.94),(55.69±6.06),(49.01±5.73),(12.84±3.37),(7.32±2.39)/visual field](P < 0.05). CONCLUSION: Phycocyanin can obviously improve the neurologic function, reduce the size of brain infarction and down-regulate the expression of Caspase-3 mRNA of rats with ischemia and reperfusion injury, thus protect brain. BACKGROUND: Phycocyanin can anti-oxidize and clear free radial. Whether its protective effect on brain is related to Caspase-3, the promoter and operator of apoptosis, is highly concerned. OBJECTIVE: To observe phycocyanin for protecting nerve function and reducing the size of cerebral infarction of rats with brain ischemia-reperfusion and its effect on the expression of Caspase-3 mRNA. DESIGN: A randomized controlled experiment. SETTING: Institute of Cerebrovascular Disease, Affiliated Hospital of Medical College of Qingdao University. MATERIALS: Totally 84 adult healthy female Wistar rats, weighing 210 to 250 g, of clean grade, were provided by the Animal Experimental Center of Shandong University. Phycocyanin (Institute of Oceanography of Chinese Academy of Sciences) was used. METHODS: This experiment was carried out in the Key Laboratory for Prevention and Treatment of Brain Diseases during May to December 2005. ① The rats were randomized into sham-operation group (n = 4), control g Middle cerebral artery occlusion / reperfusion (MACO / R) models were created on the rats of control and phycocyanin-treated groups with suture-occluded method by inserting a thread (n = 40) After the ischemia for 1 hour and reperfusion for 2 hours, suspension of phycocyanin was intragastrically administrated into the rats of the phycocyanin-treated group at 100 mg / kg, and the same volume of normal saline was isochronously administrated into the rats of control group as the same. ② Six rats were chosen individually from the control group and phycocyanin-treated group, then neurologic impairment degrees of rats were administered according to Bederson’s grading. ③ Six rats were chosen respectively from the control and phycocyanin-treated groups. The isolated brain tissue was stained with triphenyltetrazolium chloride, and then the size of cerebral infarction was calculated with HPIAS-1000 image analytical system by calculating the ratio of cerebral infarction size at each layer and contralateral hemisphere size of the same layer. ④ Twenty-eight rats were chosen respectively from the control and phycocyanin-treated groups. Brain tissue was harvested at reperfusion for 6, 12, 24 hours and for 2,3,7 and 14 days after ischemia for 1 hour, respectively, 4 rats at each time point. Brain tissue of 4 rats of sham-operation group was harvested at the 24th hour after operation. Brain tissue sections were performed in situ hybridization detection of Caspase-3 mRNA. MAIN OUTCOME MEASURES: Comparison of neurologic impairment degree, cerebral infarction size and the expression of brain tissue Caspase-3 mRNA of rats between two groups. RESULTS: Totally 84 rats entered the stage of result analysis. ① Bederson’s scores at ischemia and reperfusion for 24 and 48 hours were significantly lower in the phycocyanin-treated group than in the control group (P <0.05). ② After brain ischemia and reperfusion, the infarction area was the largest in the 3rd layer in both control and phycocyanin-treated group, which was (25.23 ± 0.47)% and (23.09 ± 1.20)%, respectively, and the size of infarction area in the 2nd layer to the 5th layer was significantly smaller in the phycocyanin-treated group than in the control group (P <0.05). ③ Positive cell counts of brain tissue Caspase-3 mRNA: The number of positive cells of Caspase-3 mRNA of control group was increased from cerebral ischemia and reperfusion 6 hours, the peak at ischemia and reperfusion 24 hours, began to decrease 2 days later and positive cells of Caspase-3 mRNA were still expressed on the 14th day After reperfusion. At ischemia and reperfusion 6,12 and 24 hours as well as 2,3,7 and 14 days, positive cell counts of Caspase-3 at peripheral ischemic area were significantly lower in the phycocyanin-treated group [(70.67 ± 3.65 ), (85.06 ± 4.79), (119.54 ± 5.37), (74.26 ± 2.19), (62.0 8 ± 3.34), (23.11 was significantly higher than that of control group [(94.38 ± 8.28), (108.81 ± 16.11), (140.88 ± 14.47), (98.13 ± 11.31), (81.03 ± 9.31), (31.22 ± 8.86), (16.06 ± 5.96) / visual field] (P <0.05); and those at central ischemic area were also significantly lower in the phycocyanin-treated group [(33.86 ± 4.01), (39.51 ± 3.46), (50.96 ± 2.53), (43.07 ± 4.09), (36.25 ± 3.72), (9.03 ± 3.87), (4.91 ± 5.59) / visual field than in control group [(51.35 ± 2.13), (54.87 ± 3.42) , (61.77 ± 4.94), (55.69 ± 6.06), (49.01 ± 5.73), (12.84 ± 3.37), (7.32 ± 2.39) / visual field respectively (P <0.05) .Conclusion: Phycocyanin can improve the neurologic function, reduce the size of brain infarction and down-regulate the expression of Caspase-3 mRNA of rats with ischemia and reperfusion injury, thus protect brain.