PATHOLOGICAL CHANGES OF THE MIDDLE CEREBRAL ARTERY IN HYPERTENSIVE RATS WITH SPONTANEOUS CEREBRAL APOPLEXY

Jingjing Huang¹, Yanglingling², Yuanjiao Weng¹, Liyu Huang¹, Yanping Zheng¹, Min Chen^1*

¹Department of Neurology, Affiliated Hospital of Putian University, Putian 351100, Fujian Province, China - ²Department of Neurology, The Eighth People's Hospital, Hengshui City, 283800, Hebei Province , China

Objective: The purpose of this study was to investigate pathological changes in the ultrastructure of the middle cerebral artery in rats with spontaneous stroke and hypertension.

Methods: We observed dynamic changes in the ultrastructure of the middle cerebral artery and the ratio of smooth muscle layer area to total culture medium area in rats with double-kidney double-clip renal vascular hypertension (RHR).

Results: The experimental data showed that the RHR model was established by double kidney injection. Experimental animals were killed at 10, 30 and 100 d for observation by transmission electron microscopy, and quantitative analysis was conducted. 1) Transmission electron microscopy: by 10 d the elastic membrane in hypertensive animals had become slightly thickened and internal smooth muscle cells were somewhat enlarged; however, there was no obvious cirrhosis; by 30 d, the pseudopodia of endothelial cells had extended into the internal elastic membrane, the smooth muscle cell membrane layers had thickened and become more irregular, there were increased numbers of cell bodies, intercellular space had increased, and the extracellular matrix had expanded; by 100 d, smooth muscle cells had become irregular in shape and expanded into the intercellular space, cytoplasm was fragmented and there was patchy necrosis. (2) Quantitative analysis of the area of internal smooth muscle: the ratio of the area of internal smooth muscle to the total area of the middle cerebral artery was not significantly different in the hypertensive group at 10 d and 30 d. However, compared with the control group and the 10 d and 30 d hypertensive groups, the ratio was significantly lower at 100 d (P<0.01).

Conclusion: We have shown that thickening of the external stroma of cerebrovascular wall smooth muscle cells and decrease in the area of mesomembrane smooth muscle cells due to large-scale necrosis may be related to the occurrence of stroke at the advanced stages of hypertension.