ABSTRACT
Objective To investigate the effects of of inhibition of AMP-activated protein kinase (AMPK) on cytochrome c (CytC) expression in the cortex and hippocampus after focal cerebral ischemia-reperfusion in mice. Methods Thirty-six male C57BL/6 mice were randomly divided into 3 groups: a sham operation group, an ischemia-reperfusion group, and a compound C group (n = 12 in each group). The mice of the compound C group were intraperitonealy injected an AMPK specific inhibitor compound C (20 mg/kg) at the time of ischemia. A model of middle cerebral artery occlusion was induced by a modified suture method. After 24 h of reperfusion, Western blot was used to detect the expression levels of AMPK, phosphorylated-AMPK (p-AMPK), and cytoplasm CytC in the cortex and hippocampus in the ischemic side. Results p-AMPK/MPK levels in the cortex in the sham operation group, ischemia-reperfusion group, and compound C group were 0. 701 ± 0. 197, 1. 408 ± 0. 322, and 0. 930 ± 0. 229, respectively (F = 12. 000, P =0. 001); p-AMPK/MPK levels in the hippocampus were 0. 685 ± 0. 228, 1. 507 ± 0. 418, and 0. 964 ± 0. 378, respectively ( F = 8. 530, P = 0. 003 ); p-AMPK/AMPK levels both in the cortex ( P < 0. 001 ) and hippocampus (P = 0. 001) in the ischemia-reperfusion group were significantly higher than those in the sham operation group, p-AMPK/AMPK levels both in the cortex (P = 0. 005) and hippocampus (P = 0. 017) in the compound C group were significantly lower than those in the ischemia-reperfusion group. CytC levels in the cortex in the sham operation group, ischemia-reperfusion group, and compound C group were 0. 496 ±0. 278, 1. 461 ± 0. 321, and 1. 018 ± 0. 175, respectively (F = 19. 915, P < 0. 001); CytC levels in the hippocampus were 0. 511 ± 0. 257, 1. 610 ± 0. 441, and 0. 921 ± 0. 228 (F = 17. 795, P < 0. 001); CytC levels both in the cortex (P < 0. 001) and hippocampus (P < 0. 001) in the ischemia-reperfusion group were significantly higher than those in the sham operation group, while CytC levels both in the cortex (P = 0. 011) and hippocampus (P = 0. 002) in the compound C group were significantly lower than those in the ischemia-reperfusion group. Conclusion Inhibition of the AMPK may down-regulate the cytoplasm CytC expression in the cortex and hippocampus after cerebral ischemia-reperfusion in mice.
ABSTRACT
Objective To investigate the effects of Saussurea involucrata extract pretreatment on the expression of the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) in focal cerebral ischemia/reperfusion in mice and its possible neuroprotective mechanism.Methods Seventy-two Kunming mice were randomly divided into four groups:sham operation,saline,Saussurea involucrata extract,and edaravone groups (n =18 in each group).Saussurea involucrata extract 0.8 g/kg was given intraperitoneally in the Saussurea involucrata extract group; edaravone 3 mg/kg was given in the edaravone group; and the same volume of saline was given in the saline group.A model of middle cerebral artery occlusion (MCAO) was induced after 7 days of continuous injection.Cerebral infarct volume was determined by 2,3,5-triphenyltetrazolium staining.Immunohistochemical staining was used to detect TLR4-positive cells in ischemic brain tissue.Reverse transcriptase polymerase chain reaction was used to detect the expression of TLR4/NF-κB mRNA.Results The cerebral infarct volume in mice in the saline,Saussurea involucrata extract and edaravone groups was 131.55± 28.25 mm3,84.10 ±13.92 mm3 and 65.10 ± 6.78 mm3,respectively.There were significant difference (F =10.158,P =0.012).The infarct volume in the Saussurea involucrata extract group (P =0.020) and edaravone group (P0.005) was significantly less than that in the saline group,and there was no significantly difference between the 2 groups.The numbers of cortex and TLR4 positive cells in hippocampus area at the ischemic sides in the saline group were significantly more than those in the sham operation group (all P ＜0.001).The numbers of positive cells of cortex and TLR4 in the Saussurea involucrata extract group and the edaravone group were significantly decreased compared to the saline group (all P ＜ 0.05),and there was no significant differences between the Saussurea involucrata extract group and the edaravone group.The expressions of TLR4,p50,and p65 mRNA in the saline group were significantly up-regulated compared to the sham operation group (all P =0.000).Saussurea involucrata extract could significantly down-regulate the expressions of TLR4,p50,and p65 mRNA at 24 hours after ischemia/reperfusion (all P =0.000).Edaravone could significantly down-regulate the expressions of TLR4 and p65 mRNA (all P =0.000) and it had a down-regulated trend for the expression of p50 mRNA (P =0.053); while there was no significant difference in the expressions of TLR4 and p65 mRNA between the Saussurea involucrata extract group and the edaravone group.Conclusions Saussurea involucrata extract pretreatment may significantly reduce the cerebral infarct volume,down-regulate the expressions of TLR4 and NF-κB subunit,and play a neuroprotective effect by inhibiting inflammatory response after ischemia.