大鼠液压脑损伤后早期脑微血管基底膜成分改变及MMP-9表达的实验研究

目的研究大鼠液压脑损伤后早期脑微血管基底膜成分的改变及MMP-9的表达并探讨其临床意义。方法成年健康SD雄性大鼠64只，以侧位液压冲击法建立大鼠脑损伤模型（8只），随机平均分为正常对照组（8只）、假手术组（8只）及颅脑损伤后3h、6h、12h、24h、48h、72h亚组（每亚组8只）。应用光镜、透射电镜及免疫组化法观察大鼠脑损伤后不同时间点脑微血管结构、Ⅳ型胶原及MMP-9表达。结果颅脑损伤后脑微血管外细胞间质水肿，基底膜节段性溶解、缺损，有红细胞漏出；脑微血管基底膜Ⅳ型胶原明显减少；MMP-9的表达逐渐增强。结论液压脑损伤后脑微血管基底膜缺失是导致继发性脑水肿及脑缺血的主要病理基础，而脑微血管壁和管外间质MMP-9高表达可能是引起微血管损害的主要机制之一。

Cerebral Microvessel Basal Lamina Antigen Loss and Expression of MMP-9.after Lateral Fluid Percussion Brain Injury in Rats

Objective To study changes in the basal lamina antigen of brain microvasculature and the expression of MMP-9 after lateral fluid percussion brain injury. Methods Sixty-four male Sprague-Dawley rats were randomly divided into normal control group, sham group and posttrauma 3, 6, 12, 24, 48 and 72 hours groups of 8 rats each. Lateral fluid percussion brain injury（FPI） model were produced by improved McIntosh et al method in rats. Type Ⅳ collagen antigens and the expression of MMP-9 in all the groups were determined by immunohistochemical staining. The changes in the pathology and ultrastracture of cerebral tissues were observed respectively by light and electron microscopes after the brain injury. Results The basement membrane damages included its segment degradation, defect and exfoliation after brain injury. There were red blood cells out of cerebral microvessels in the rats with brain injury. The main components of the cerebral microvessel basement membrane, type Ⅳ collagen significantly decreased 24, 48 and 72 hours after the brain injury compared to the normal control and sham groups （P〈0.05）. The expression of MMP-9 in the injured cerebral area s;gnificanfly increased 24, 48 and 72 hours after the brain injury compared to the normal control and sham groups. Conclusions The main pathological changes such as brain edema and ischemia after traumatic brain injury resulted from the damage to basement membrane of brain microvaseulature, and the decreases in the components of the basement membrane contribute to the basement membrane lesion and the loss of microvascular integrity. It is suggested that MMP-9 might play an important role in microvascular lesion after the brain injury.