Abstract:Aim To investigate the pathological changes of vascular remodeling and collagen in spontaneously hypertensive rats(SHR) and the effect of treatment by Xuezhikang. Methods 30 male SHR at 8-week-old were randomly divided into three groups (n10 each): Xuezhikang low dose group (XZK-L group,Xuezhikang 20 mg/(kg·d)),Xuezhikang high dose group (XZK-H group,Xuezhikang 200 mg/(kg·d)) and placebo group,sex and age matched Wistar rats (control group,n10) were also designed. 8 weeks after intragastric administration,the levels of serum matrix metalloproteinase-9(MMP-9) and tissue inhibitors of metalloproteinase-1(TIMP-1) were measured by enzyme linked immunosorbent assay (ELISA). The thoracic aortas were collected for hematoxylin-eosin (HE) stain to detect vascular wall thickness and Wall-to-lumen area ratio (W/L). The aortic collagen was showed by Masson trichrome stain. The thoracic aortas were observed by immunohistochemistry to detect the expressions of MMP-9 and TIMP-1. Quantitation of the protein content of MMP-9 and TIMP-1 was assessed by computerized planimetry in the aortic media in immunohistochemically stained slides by using Image-Pro Plus 6.0. Results The level of serum MMP-9 in placebo group was significantly increased compared with XZK-H group and control group (P<0.05). The levels of serum TIMP-1 in the SHR groups were higher than control group(P<0.01). There was no significance of the levels of TIMP-1 in all SHR group (P>0.05). Aortas of SHR showed wall thickening,increasing wall-to-lumen area ratio and collagen,disordered fibres. The thickness of vascular wall and W/L ratio of SHR were significantly higher than those of Wistar rats (P<0.05). Arteries in XZK group showed less collagen in aortic wall than that of placebo group,especially the XZK-H group was near to the control group. In the placebo group,MMP-9 protein expression was significantly increased in the thoracic aorta compared with control group and XZK-H group(P<0.05). However,the level of TIMP-1 had no significance in the four groups (P>0.05). Conclusions Hypertensive vascular remodeling shows elevated level of MMP-9 and collagen deposition. While Xuezhikang can inhibit the elevated MMP-9 and collagen deposition,improve vascular remodeling in hypertension.