Experimental Study The Effect Of Application Of Polyclonal Antibody Against IL-6 As Means Of Prevention And Treatment On CVS After SAH In Rats

PartⅠ: Experimental study on the expression of IL-6 in serum and BA walls following SAH in ratsObjective: To investigate the expressions of IL-6(Interleukin-6) in serum and BA(basilar artery) walls following subarachnoid hemorrhage (SAH) in rats and to study the relationships with cerebral vasospasm (CVS).Methods: 51 health male Sprague-dawley(SD) rats were assigned randomly into following groups: Normal group, Control group(injected normal sodium through cisterna magna only), SAH group. The control and SAH groups then were assigned into 5 subgroups according to time points(1d,3d,5d,7d and 14d,Control group: n=3; SAH group: n=6). Double autologus arterial blood injection through cistema magna was underwent to establish SAH model in rats. The morphologic changes of BA were examined with hemotoxylin and eosin(HE) staining, and the expressions of IL-6 in plasma following SAH at different time point were detected by ELISA, whereas in BA walls by immunohistochemistry method.Results: The"two hemorrhage"model of vasospasm was succeeded to be made. Since 1st day after SAH, The serum IL-6 level in rats was increased with SAH and was higher than the normal and control groups(P<0.01) on 3rd day and 5th day,among which the highest level appeared on 3rd day. The pathological changes including arterial narrowing, thickness of arterial wall, reductus of intima and hypertrophy of smooth muscle cells could be observed and such changes progressed with time and were more obvious on 3rd day and 5th day. The luminal inner diameter of BA on 5th day after SAH was about 60% of the control group's, and the wall thickness of BA was about double times of the control group's. The expression of IL-6 increased in SAH group, and reached to the peak on 3rd day and 5th day, then decreased. The level on 14th day was similar to the control group.Conclusions: 1. The pathological changes including morphological changes, artery narrowing, thickness of arterial wall suggests that CVS happens after SAH. 2. The expression of IL-6 in serum and the BA walls has changes and been concerned with CVS. It suggests that IL-6 may participate the pathological course of vasospasm.Part II: Experimental study of the role of vascular cell proliferation on CVS after SAHObjective: To investigate the role of vascular cell proliferation on CVS after SAH. Methods: 51 health male Sprague-dawley(SD) rats were assigned randomly into following groups: Normal group, Control group(injected normal sodium through cisterna magna only), SAH group. The control and SAH groups then were assigned into 5 subgroups according to time points(1d,3d,5d,7d and 14d,Control group: n=3; SAH group: n=6). Double autologus arterial blood injection through cisterna magna was underwent to establish SAH model in rats. The expressions of PCNA(proliferating cell nuclear antigen)in BA walls following SAH at defferent time point were detected by immunohistochemistry method.Results: Immunohistochemical study showed that the expression of PCNA in BA walls could be observed in all groups. There was a weak expression in normal and control groups. The expression was obviously increased with SAH and was higher than the normal and control groups(P<0.01) on 1st day to 7th day,among which the highest level appeared on 5th day. The level on 14th day was similar to the control group. Conclusions: The expression of PCNA in BA walls has been upregulated after SAH, reaching the peak on 5th day. It suggests that vascular cell proliferation and subsequent vessel wall thickening may play a role in the pathological course of vasospasm after SAH.Part III: Experimental study of the effect of polyclonal antibody against interleukin-6 on CVS after SAHObjective: To evaluate the effect of neutralizing antibody against interleukin-6 on CVS after SAH.Methods: The"two hemorrhage"model of vasospasm was performed. We administered increasing doses of a polyclonal antibody against rat IL-6(the dosage in LD group is 20μg/10μl and in HD group is 40μg/10μl) directly into the cisterna magna as means of prevention and treatment before the second blood injection, while Control animals received an equal volume of PBS into the cisterna magna. We observed morphological changes and the expression of IL-6 and PCNA in BA walls by light microscopy and immunohistochenistry.Results: Compared with SAH 5d group, diameter of BA in HD group was expanded, thickness of BA walls and CVS value were decreased with a statistical difference (p <0.05), while LD group had no difference (P> 0.05). The expression of IL-6 in BA walls in SAH 5d group was strong, especially in media and adventitia , whereas it was slight in LD group and no obvious in HD group.The expression of PCNA was more slight in treatment groups than those in contral groups(P<0.01), what's more, different dose of polyclonal antibody against interleukin-6 showed different effect.Conclusions: Polyclonal antibody against interleukin-6 showed good effect for prevention and treatment on CVS after SAH and was like to be dose-dependent. At the same time that polyclonal polyclonal antibody against IL-6 could reduce vascular cell proliferation of the BA walls.