硫酸鎂在局部性腦中風沙鼠腦內對葡萄糖運輸蛋白3、ERK蛋白及凋亡的影響

Effects of magnesium sulfate on glucose transporter 3, extracellular signal-regulated kinase and apoptosis in gerbil brain following focal cerebral ischemia

劉憶帆(Yi-Fan Liu)

指導教授 ： 林靜瑩

中臺科技大學/健康科學院/生命科學研究所/碩士(2008年)

摘要

腦中風是導致死亡與殘障最重要的原因之一。研究也指出鎂離子在腦部局部性缺血的動物模式及病人中風時具有保護作用，但鎂離子是透過哪些訊號及機制去調控和保護神經細胞仍舊不清楚。腦部的葡萄糖運輸蛋白型態為葡萄糖運輸蛋白3 (glucose transporter 3, GLUT3) ，位於神經細胞的細胞膜上，是將葡萄糖運輸供給神經細胞，主要是供應能量及維持神經細胞的生存。資料顯示，在局部性腦缺血時ERK (extracellular signal-regulated kinase)，CREB (cyclic AMP response element-binding protein) 為影響神經細胞生存之蛋白。本研究目的主要著重於探討鎂離子在沙鼠局部性腦缺血對於 GLUT3、ERK 和凋亡的影響。實驗為對照組及局部缺血前30分鐘腹腔注射Saline和 Magnesium sulfate (MgSO4) (90mg/5ml/kg) 之後結紮右側之中腦動脈 (middle cerebral artery, MCA) 及總頸動脈 (common carotid artery, CCA) 30分鐘和60分鐘犧牲，從 TTC 染色的腦切片中發現MgSO4 對腦梗塞面積有明顯減小的情況，且利用 Western Blot 也觀察局部腦缺血前注射 MgSO4 使得 GLUT3 蛋白表現及 anti-apoptotic Bcl-2 蛋白表現量有顯著增多，活化 pCREB和ERK 蛋白，也降低 pro-apoptotic Bad, Bax, caspase-9 and caspase-3 的表現。由實驗結果在沙鼠局部腦缺血前注射 MgSO4 具有保護神經細胞的作用，也許在未來可以應用在預防和治療腦中風。

關鍵字

沙鼠 ； 葡萄糖運輸蛋白3 ； 局部腦缺血 ； 硫酸鎂

並列摘要

Background. Cerebral stroke is a cause of death and disability. Previous studies have demonstrated that magnesium has cytoprotective properties for treating experimental rat brain injuries, however the information and mechanisms regarding the protective effects of magnesium sulfate on neurons still remains unclear. The brain type glucose transporter GLUT3 (glucose transporter 3) is mainly located neuron plasma membrane and contributes to glucose transport into neuronal cells as the major usage of energy source to maintain neuron survival. Evidences also showed that ERK (extracellular signal-regulated kinase), CREB (cyclic AMP response element-binding protein) protein promote neuronal survival in the face of global ischemia. In the present study, we further evaluate the effects of magnesium sulfate on regulation of GLUT3, ERK protein and apoptosis during experimental focal cerebral ischemia. Methods. The experiments were conducted on male gerbils at 8 weeks of age, weighing 65-80g. The gerbils colonies were housed under 12-h light/dark cycles at 26 °C and fed regular chow and tap water. Gerbils at 8 weeks of age randomly were divided into 4 groups. Focal cerebral ischemia was induced by occlusion of the right common carotid artery and right middle cerebral artery (CCA + MCA) for 60 min and 30 min. Magnesium sulfate (90 mg/kg, i.p) and saline were given 30 min prior to the occlusion. Experiments were performed by TTC assays and western blotting assays. Results. Magnesium sulfate treatment significantly upregulated GLUT3 protein and anti-apoptotic Bcl-2 protein, and activated ERK protein. Magnesium sulfate treatment significantly decreased (CCA + MCA)-induced the expression of pro-apoptotic Bad, Bax, caspase-9 and caspase-3 in cortex. Conclusions. These studies demonstrated that magnesium sulfate provides significant neuroprotection in a gerbil model of focal cerebral ischemia by the increases in GLUT3 and anti-apoptotic Bcl-2, the reduction of pro-apoptotic proteins (e.g. Bad, Bax, caspas-9 and caspase-3), the activation of ERK protein. These findings may provide one of possible therapeutic approach for potential treatment or preventing stroke.

並列關鍵字

Magnesium sulfate ； gerbil ； GLUT3 ； focal cerebral ischemia

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