Role of estrogen on expression of TNF-α and MMP-9 in intracranial arterial vascular wall of spontaneous hypertensive rats

AIM: To study the effects of estrogen on the inflammatory response and vascular remodeling of intracranial artery in rats.METHODS: Thirty-two female spontaneous hypertensive rats (SHR) were randomized into 4 groups: spontaneous hypertensive group(sham-operated), ovariectomized group, ovariectomized+17 beta-estradial group and ovariectomized+vehicle group (8 rats in each group).On day 14, estradiol was detected by radioimmunoassay.The pathological changes were observed under light microscope.The protein expression of tumor necrosis factor alpha (TNF-α) and matrix metalloproteinase-9 (MMP-9) in vascular wall of Willis circle was detected by Western blotting.RESULTS: The estrogen level was lower in ovariectomized group than that in sham-operated group (P<0.01).The estrogen level was higher in ovariectomized rats treated with 17 beta-estradial than that in ovariectomized rats treated with vehicle (P<0.01).Advanced aneurysm was not found in all groups.Early aneurysmal change was not found in sham-operated group.Early aneurysmal changes in some rats were observed in ovariectomized group (2 rats), ovariectomized+vehicle group (3 rats) and ovariectomized+17 beta-estradial group (1 rat).The protein levels of TNF-α and MMP-9 in the vascular wall of Willis circle in sham-operated group were lower than that in ovariectomized group (P<0.01).Additionally, the protein levels of TNF-α and MMP-9 in the vascular wall of Willis circle of ovariectomized rats treated with 17 beta-estradial were lower than those of ovariectomized rats treated with the vehicle (P<0.01).CONCLUSION: Estrogen can influence the vascular remodeling of intracranial artery by inhibiting the inflammatory response and degradating MMP-9 in the vascular wall.