| PurposeThe aims of this experiment are to study the mechanisms of the cochlear injury during vertebrobasila inchemia reperfusion in guinea pig,investigate the protective effects of alpha-lipoic acid on the lesion.Materials and MethodsOne hundred and eight healthy guinea pigs with positive preyer's reflex weighted from 300 to 350 grams were randomly assgined to 9 groups (n-12) :the normal control group ,the sham operated group,the ischemia (Ihour) group,the reperfusion group (6,24,48hour, lOday), alpha-lipoic acid group and normal saline group.The models of vertebrobasilar ischemia reperfusion were established as below: unilateral carotid and basilar artery were occluded for 1 hour using specialized microvascular clamp,then theclamp was removed and the blood flow restored at the time point (6,24,48hour, 10day).The models of alpha-lipoic acid group was received alpha-lipoic acid (100mg/kg d) intraperitoneally for seven days before the onset of ischemia. The last group was received normal saline (NS) instead of alpha-lipoic acid. The animals of these two groups were killed in the tenth day after operation.Results1 . Changes of ABR in the vertebrobasilar ischemia and ischemia-reperfusion conditions consisted of a delay in all wave latencies and a increase of the auditory thershold.There were significant differences compared with the control group (P<0. 01). Compared with the 10 day group,the lateneies shorten and the thresholds decreased of the a -lipoic acid group (PO.05); 2. Lesions were detected in the hair cell and the stria vascularis ischemia group. Compared with the ischemia groups,the hismorphological features could be seen in the reperfusion groups. These injuries of the drug group were more alliviative than that of the 10 day group;3 . The CAT activities decreased and MDA concentrations increased in the ischemia group and reperfusion groups. Compared with the control group,there was significant difference.However, compared with 10 day group,it had a contrary result of drug group and there was also significant difference between them; 4. Compared with central group,labeling ratio of NF- K B expression in cochlea decreased in ischemia group and reperfusion groups. It increased in drug group than that of reperfusion to 10 day group.-6-Conclusion1. ABR can sensitively reflect the degree of brainstem ischemia reperfusion injury in auditory pathway.2. The vertebrobasilar ischemia reperfusion injury can cause the lesions of cochlea.3 . CAT activities and increase of MDA contents of cochlea can be caused by the vertebrobasilar ischemia reperfusion injury . It indicates that free radical play an important role in this kind of injury.4. The NF- K B takes part in the ischemia - reperfusion injury.5. The lesion of cochlea and the losing of hear resulted from ischemia reperfusion injury can be protected by alpha-lipoic acid. |
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