fa بررسی ‌میزان بیان آنزیم تبدیل‌کننده‌ی TNF-a (TACE) و سطح فعالیت NF-kB در پدیده‌ی تحمل به ایسکمی‌‌ حاصل از هیپرکسی نورموباریک متناوب در مدل موش صحرایی سکته‌ی مغزی <p style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><strong><em>Background and objective:</em></strong> Recent studies suggest that intermittent and prolonged normobaric hyperoxia (HO) results in ischemic tolerance to reduce brain injury. In this research attempts were made to see the changes in TNF-a converting enzyme (TACE) and NF-kB activity following intermittent HO and ischemia preconditioning.<br> <strong><em>Materials and Methods:</em></strong> The rats were divided into two experimental groups, each consisted of 20 animals. The first group was exposed to 95% inspired HO for 4h/day for 6 consecutive days (intermittent HO; InHO). The second group acting as the control, was exposed to 21% oxygen in the same chamber (normobaric normoxia or room air; RA) continuously for six days (intermittent RA; InRA). Each main group was subdivided to MCAO-operated (middle cerebral artery occlusion), sham-operated (without MCAO), and intact (without any surgery) subgroups. After 24hr, MCAO-operated subgroups were subjected to 60 min of right MCAO. After 24 h reperfusion, neurologic deficit score (NDS) and infarct volume were assessed in MCAO-operated subgroups. Immediately and 48 h after pretreatment, blood sampling for assessment of serum TNF-a levels were subjected. Then, the effect of intermittent HO and ischemia on NF-kB activity and TACE expression were measured.<br> <strong><em>Results:</em></strong> Preconditioning with intermittent HO and ischemia decreased NDS and infarct volume. Moreover InHO and MCAO-InHO upregulate TACE and increase NF-kB activity significantly.<br> <strong><em>Conclusion:</em></strong> Although further studies are needed to clarify the mechanisms of ischemic tolerance, InHO and ischemia seem to partly exert their effects via increase upregulation of TACE and NF-kB activity.</span></span></p> <p></p><p></p> Normobaric hyperoxia, Brain ischemia tolerance, Stroke, TACE, NF-kB activity 63 74 http://journal.zums.ac.ir/browse.php?a_code=A-10-4-78&slc_lang=fa&sid=1 Mehdi Rahnema مهدی رهنما meh_rahnema@yahoo.com 5200319475328460057934 5200319475328460057934 Yes Department of Biology, Islamic Azad University of zanjan, Iran Mohammad Reza Bigdeli محمدرضا بیگدلی 5200319475328460057935 5200319475328460057935 No