Effects of Saussurea involucrata extract pretreatment on the expression of the Toll-like receptor 4/nuclear factor-κB in focal cerebral ischerrda/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 faetor-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 goups： 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 involuerata 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, Immunohistochemieal 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-KB mRNA. Results The cerebral infarct volume in micein the saline, Saussurea involucrata extract and edaravone groups was 131.55± 28.25 mm3, 84. 10± 13.92mm3 and 65. 10 ± 6. 78 mm3, respectively. There were significant difference （F = 10. 158, P = 0. 012）. The infarct volume in the Sanssurea involuerata 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 involuerata 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 sigaificantly up-regulated compared to the sham operation group （all P= 0. 000）. Saussurea involuerata 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 involuerata extract group and the edaravone group. Couelusiora 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. Key words: Brain Ischemia; Reperfusion Injury; Toll-Like Receptor 4; NF-κB; Herba SaussureaeInvolucratae; Neuroprotective Agents; Disease Models, Animal; Mice