Effects of thyroid hormone on NF-κB and TNF-α in cerebra cortex of rats with brain ischemic reperfusion injury

Objective To investigate the effect of thyroid hormone on the expression of NF-κB and TNF-α in the ischemic cortex of rats after focal cerebral ischemia- reperfusion. Methods 96 male SD rats were randomly divided into sham-operation group, sham-operation+ T3 group, IR group and IR+ T3 group. Using suture legal method to establish a rat model of middle cerebral artery occlusion for 2 h followed by reperfusion.In sham-operation+ T3 group and IR+ T3 group, T3 was given 3 days before ischemia and 1 hour after ischemia, respectively, intraperitoneal injection T3 10 μg/100 g for rats. Rats in other groups were given the same volume normal saline at the same time. The infarct size was determined by TTC staining at 24 h after reperfusion. HE staining was used to observe the morphological and structural changes of brain tissue. Using Real-time PCR method and immunohistochemical staining method to detect the expression of NF-κB mRNA, TNF-α mRNA and protein in ischemic cortex of rats. Results Compared with sham-operation group and sham-operation+ T3 group, the pathological damage of brain tissue in IR group was obvious, while the pathologic damage of IR + T3 group was less than that in IR group. Immunohistochemistry assay showed that the expression of NF-κB was(49.19±5.55)in sham-operation group, (45.75±2.12) in sham-operation+ T3 group, (56.88±2.23)in IR group and(50.25±1.67)in IR + T3 group, the expression of TNF-α was (22.50±3.07) in sham-operation group, (24.13±2.03) in sham-operation+ T3 group, (37.25±2.82) in IR group and (30.25±1.67) in IR + T3 group, and the NF-κB, TNF-α in IR group were obviously higher than that in sham-operation group and sham-operation+ T3 group(P<0.05), while IR+ T3 group were lower than that in IR group(P<0.05). Real-time PCR showed that NF-κB mRNA, TNF-α mRNA level in IR group was the highest, which was higher than that of sham-operation group and sham-operation+ T3 group(P<0.05), and the NF-κB mRNA, TNF-α mRNA expression in IR+ T3 group were significantly decreased compared with that in IR group(P<0.05). Conclusion Thyroid hormone has a protective effect on cerebral ischemia reperfusion injury, which may be achieved by reducing the expression of inflammatory factor NF-κB and TNF-α. Key words: Thyroid hormone; Ischemia-reperfusion injury; Inflammation; NF-κB; TNF-α