大鼠脑内大分子物质的引流通路及方法学研究

DRAINAGE OF MACROMOLECULES FROM THE RAT BRAIN AND THE METHODOLOGY STUDY

为探讨脑内大分子物质的引流通路,本研究微量注射示踪剂墨汁到大鼠右侧尾壳核,Ⅰ组动物使用传统的脑内注射方法,Ⅱ组动物采取改良方法防止示踪剂从进针处进入蛛网膜下腔,术后1、3、7、14、21 d处死动物,分别用肉眼、光镜及电镜观察墨汁在脑内、蛛网膜下腔、颈总动脉及颈部淋巴结的分布。结果显示:墨汁在两组动物脑实质内的分布趋势相同,即在白质内沿神经纤维弥漫性分布,7 d后在灰质内选择性地沿血管周围间隙分布,部分碳颗粒被管周细胞和巨噬细胞吞噬;Ⅱ组动物中观察到墨汁从大脑顶部进入蛛网膜下腔后沿其中的血管周围间隙分布并引流到脑的底部和嗅球及筛板区域,在耳蜗、前庭蜗神经和视神经等的脑神经鞘以及颈总动脉壁和颈部淋巴结有碳颗粒沉积;Ⅰ组动物没有这种分布。以上结果表明,大鼠脑实质内的大分子物质在白质和灰质中的引流方式不同;进入脑脊液的大分子物质可由颈部淋巴系统引流;墨汁不是很好的研究脑实质内大分子物质引流的示踪剂。

To study the drainage pathway of macromolecules from the rat brain, Chinese ink was injected into the right cau-date-putamen(CPu). Traditional injection method was used in animals of group Ⅰ, and the improved method to prevent the tracer from entering the subarachnoid space was used in animals of group Ⅱ. Animals were killed by paraformaldehyde perfusion 1,3, 7, 14 and 21 days after injection, and the distribution of ink was observed by macroscopy, light and electron microscopy. The results showed that carbon particles were distributed diffusely along nerve fibers in the white matter at all time intervals whereas they spread selectively along perivascular spaces in the gray matter 7 days after the injection and some was ingested by perivascu-lar cells and perivascular macrophages. In group Ⅰ, carbon particles entered the subarachnoid space over the vertex of the cerebral hemispheres and drained along perivascular spaces to the base of the brain and olfactory bulbs. Carbon particles were also found in cribriform plate, nasal mucosa and cochlea, around vestibulocochlear nerve and optic nerve, in the wall of carotid artery and in cervical lymph nodes in the same group. These results suggeste that the drainage pathway of macromolecules in the gray matter is different from that of the white matter, the macromolecules in cerebrospinal fluid can be drained by cervical lymphatics, and Chinese ink is not a good tracer for studying the drainage of macromolecules from the brain parenchyma.