Influence of N-acetylcysteine on expressions of nuclear factor-kappa B in local cerebral ischemia-reperfusion

Lijie CHEN; Songlan LIANG; Bingrong LIU; Qingcheng LIANG

ABSTRACT

BACKGROUND:

Nuclear factor-kappa B (NF-κB) is an important transcription factor, which can promote the transcription of many target genes after activated.

OBJECTIVE:

To investigate the expressions of NF-κB in local cerebral ischemia-reperfusion and the influence of the pretreatment of the N-acetylcysteine.

DESIGN:

Randomized grouping experiment with animals as subjects.

SETTING:

Department of Neurology, the Second Clinical Medical College, Harbin Medical University.MATERIALS The experiment was finished in the Animal Experimental Center and Laboratory of Pathology of Harbin Medical University. Ninetynine male healthy Wister rats were randomly divided into 3 groups Sham-operated group(n=l 1), saline control group(n=44), N-acetylcysteine group(n=44).

METHODS:

Rat models of cerebral ischemia were made with the method of thread blocking improved by Longa et al in rats of the three groups. A nylon line with a smooth spherical captular end of 0.26 mm in diameter made by heating was inserted through the cut of crotch of the common carotid artery. The prepared line for common carotid artery was tied tightly and the arteriole clamp of internal carotid artery was unclamped. The nylon line entered the common carotid artery and the inserted length of the saline control group and the N-acetylcysteine group from the crotch of the internal and external carotid artery was calculated about (18.5±0.5)mm in order to obstruct the blood supply of the middle cerebral artery. The inserted depth in sham-operated group was less than 15 mm and the blood supply of the middle cerebral artery was kept normal. Intraperitoneal injection of N-acetylcysteine was given with 150 mg/kg at 30 minutes before ischemia in N-acetylcysteine group and injection of normal saline was given with equal volume at 30 minutes before ischemia in saline control group.Eleven rats each time in saline control group and N-acetylcysteine group were killed by cutting off heads at the time points of ischemia 6, 24 hours,and reperfusion 1 hour after ischemia 6, 24 hours. The express of NF-κB of brain tissue was observed with immunchistochemical method. Percentage of cerebral infarction of rats in each group was determined by dyeing of tetrachloro red tetrazoline. Apoptosis of brain tissue cells was detected with terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL).MAIN OUTCOME MESURES Percentage of cerebral infart volume of rats in each group, the activity of combination of the NF-κB and apoptosis of cells.

RESULTS:

Ninety-nine animals attended the experiment, all of them entered the final analysis. ① Percentages of infarct volume at 1 hour of ischemia and 6, 24 hours of reperfusion in N-acetylcysteine group were (8.39±2.54)%, (24.54±6.02)% respectively, and that of corresponding saline control group were (15.50±4.18)%,(32.22±3.99)%. The focus of infartion with ischemia for 24 hours in each group was increased as compared with that for 6 hours and the infarct volume in group with N-acetylcysteine was obviously decreased as compared with that in saline control group (P ＜ 0.01). ② NF-κB p56 transfered from the kytoplasm to the nucelus after the ischemia and reperfusion. The rates of p56 masculine cells in N-acetylcysteine group of ischemia for 6 and 24 hours were (0.462±0.022)%, (0.452±0.015)% respectively, the express of which was decreased as compared with that in saline control group [(0.563±0.028 )%,(0.554±0.013)%] (P ＜ 0.01 ). ③ Cells of apoptosis pretreated with N-acetylcysteine were obviously decreased as compared with that pretreated with normal saline.

CONCLUSION:

Focal cerebral ischemia and reperfusion can activate NF-κB p65, which participate in the damage of cerebral ischemia and reperfusion. NF-κB can inhibit the express of p65, and relieve the nerve injury and so have the effct of protection for brain.