저산소성 허혈성 뇌손상을 유발시킨 어린 흰쥐에서 P-selectin의 mRNA 및 단백질 발현

초록

Purpose : The selectin family of adhesion molecules plays a role in the initiation of endothelium-leukocyte interaction of inflammation and ischemia-reperfusion. P-selectin, a rapidly expressed endothelial cell adhesion molecule, is essential for both neutrophil rolling after endothelial stimulation and neutrophil transmigration. P-selectins were expressed after brain injury and could play an important role in the pathogenesis of ischemic brain injury in adult animal. However, the mechanisms leading to post-hypoxic-ischemic injury in immature brain are unknown yet. We hypothesize that P-selectin might mediate post- hypoxic-ischemic injury in immature rat brain. We evaluated the expression of mRNA and protein of P-selectin in post-hypoxic-ischemic immature rat brain. Methods : In isoflurane-anesthetized P7(Postnatal day 7) Sprague-Dawley rats(n=81), the right carotid artery was isolated and coagulated. 1-2 h later animals were exposed to 8% oxygen(balanced with nitrogen) for 2 h in glass chambers, in a warm air incubator (temperature maintained at 36.5℃). Control included carotid artery coagulation alone, hypoxia alone, and normal(neither hypoxia nor coagulation). For RNA extraction, the rats were decapitated at 0, 2, 4, 8, 12, 24 and 48 h after hypoxic-ischemic injury. For Western blot analyses with P-selectin, rats were decapitated at 0, 15, 30 min, 1, 2, 4, 8, 12, 24 and 48 h after hypoxic-ischemic injury. Control or hypoxia alone rats were sacrificed 8 h after the respective intervention. Results : There was no expression of P-selectin mRNA in control groups(carotid artery coagulation alone, hypoxia alone, or normal). P-selectin mRNA expression in the ipsilateral(right) hemisphere reached a peak at 8 h after hypoxia-ischemia and then barely detected after 24 h. Expression of P-selectin protein was not observed in brain tissue of control rats. P-selectin protein was detected as early as 15 min and 30 min at both hemisphere in experimental rats and decreased at 1 h. P-selectin protein increased in right hemisphere at 4 h post-hypoxia-ischemia, peaked at 8 h and no longer detectable at 24 h. Conclusion : Hypoxic-ischemic injury leads to P-selectin expression in neonatal rats brain. The temporal profiles of post-hypoxic-ischemic P-selectin mRNA and protein expression are consistent with a role in the evolution of subsequent brain injury.

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