The Effect Of Mild Hypothermia On The Expression Of TNF-α And IL-1β After Acute Cerebral Ischemia Reperfusion In Adult Rats

Objective: to explore the effect of mild hypothermia on nerve function improving and thechanges of infarction volume after acute cerebral ischemia reperfusion injury in adult rats, and the effect on the expression of TNF-αand IL-1βin the ischemia cerebral tissue.Methods: 110 adult male SD rats, weighting 280-320g, were randomly divided into 11group: nromal group (n=5) ,sham-operated group (n=5) , normal temperature treatment cerebral ischemia reperfusion (monolateral middle cerebral artery occlusion (MCAO) obstruction and reperfusion) 8h, 24h, 3d, 7d, 1m group (n=10) , mild hypothermia treatment cerebral ischemia reperfusion 8h, 24h, 3d, 7d, lm group (n=10) . The five rats of every group were used to check the expression of TNF-α,IL-1βprotein in the ischemia cerebral brain by immunohistochemistry, and the other five of them were used to check the level of the two factor's mRNA in the ischemia cerebral brain by RT-PCR. Calculate the Infarction volume after acute cerebral ischemia reperfusion and treatment by mild hyperthomia by stereology, and value their nerve function status using Longa score.Results: the number of TNF-α,IL-1βimmunoreactivities reached peak at 1d after cerebralischemia reperfusion, then decreased rapidly at 3d, and maintained at the lowest level at 7d. the number of TNF-α,IL-1βimmunoreactivities increased rapidly at cerebral ischemia groups compared with normal group and the sham-operated group. their expression decreased rapidly at the mild hypothermia treatment group, although their expression still higher than the normal group and sham-operated group. The expression of TNF-α,IL-1βand their mRNA were weak in the sham-operated group, their expression reached peak at 8h after cerebral ischemia reperfusion,then decreased, but still maintained at a higher level, and recovered to normal level at 1 month. The expression of TNF-α,IL-1βand their mRNA increased rapidly at the cerebral ischemia groups compared with the normal group and the sham-operated group. Their expression decreased rapidly at the mild hypothermia treatment group, although their expression still higher than the normal group and sham-operated group. The cerebral infarction area reached peak at 3d at the cerebral ischemia normal temperature treatment groups and mild hypothermia treatment groups, then decreased later. But the cerebral infarction area at the mild hypothermia treatment groups smaller than the normal temperature groups at 8h, 24h, 3d, 7d, and1m. The Longa score showed that the nerve function improved visibly at mild hypothermia treatment groups compared with the normal temperature treatment groups Conclusion: 1．The expression of TNF-α,IL-1βincreased rapidly after cerebral ischemiareperfusion, and mild hypothermia treatment could decrease their high degree.2．Mild hypothermia can decrease the cerebral infarction area obviously.3．Mild hypothermia can obviously improve the nerve function after cerebral ischemia reperfusion in rats. Indicated that mild hypothermia treatment could protect the cerebral ischemia reperfusion injury by decreasing the level of TNF-α,IL-1β.