大鼠短暂局灶性大脑中动脉缺血后calpain的表达

目的：研究calpain在缺血性脑损伤中的作用，进一步探讨缺血性脑血管病的分子机制，为治疗研发提供理论依据。方法：用Belayev改良的Langa线栓法制备大鼠局灶性大脑中动脉(MCA)缺血／再灌注模型，TTC染色观察梗死灶的形成，分别用原位杂交及免疫组化技术检测鼠脑中calpain mRNA与活性蛋白的表达。结果：缺血2h再灌注24h,TTC染色见明显的梗死灶形成，正常脑组织、假手术组及：MCAO缺血对侧脑中有少量的calpain mRNA表达，但活性蛋白几无表达；缺血脑组织calpain mRNA表达及蛋白质活化均显著增加，呈双峰式，MCA缺血2h增加，再灌注4h减少，至24h更明显增高，而48h又有所下降。结论：Calpain参与了缺血性脑损伤过程，尤其在迟发性神经元死亡中起重要作用。

Increased calpain expression in brain sections of rats subjected to transient focal cerebral ischemia

Objective:To study the specific patterns of calpain expression in the brain sections of rats subjected to transient focal ischemia, and to understand further the molecular mechanisms of ischemic neuronal damage.Methods:Reversible occlusion of the left middle cerebral artery (MCA) for 2 h was carried out in chloral hydrate anesthetized rats using the poly L lysine coated filament method, a modification of the intraluminal sature method of Longa established by Belayev et al . After awakening from anesthesia, neurological functions of rats were evaluated with the 5 grade scale developed by Longa, and infarct zones were confirmed by 2,3,5 triphenyltetrazolium chloride(TTC) staining. In situ hybridization and immunohistochemistry were performed at 0, 4, 24, 48 h of recirculation in MCAO rats and in sham controls. Oligonucleotide probes served for detection of calpain expression in brain sections at the mRNA level, and antibodies served for determination of calpain expression at the active protein level.Results:Low levels of calpain mRNA expression were showed but its protein expression was seldom found in control brains. Values in contralateral regions were not significantly different across different time points. Both mRNA and protein expression of calpain in ipsilateral region were increased after ischemia,and the time course of increase appeared to be bimodal, which was detected after 2 h of occlusion, decreased at 4 h of reperfusion,a delayed secondary increase in calpain activity peaking at 24 h after reperfusion.Conclusion:Calpain may involve in ischemic brain injury, and it might play an important role in delayed neuronal death after cerebral ischemia.