Experimental Study Of The Effect On MtDNA Deletion Of Nerve Cells In Intracerebral Hemorrhage And The Protective Effect Of Melatonin

【Objective】: Through the obseration of mitochondrial DNA (mtDNA) deletion and SOD, MDA to investigate the role of mtDNA deletion in the nerve cell in rats with intracerebral hemorrhage and to study the protective effect of melatonin on mtDNA after intracerebral hemorrhage.【Methods】: 110 SD rats were randomly diveded into three groups: normal group,sham-operated group, intracerebral hemorrhage group. In addition, 100 SD rats were randomly diveded into two groups: control group, melatonin intervention group. Each group was divided into 5 subgroup respectively at 12h, 1d, 2d, 4d and 7d after the establishment of animal model. Intracerebral hemorrhage model was induced by stereotaxic injection of typeⅦcollagenase (0.5U), same volume normal saline was injected in sham-group, and no treatment was done for normal group. Melatonin intervention group was injected intraperitoneally with melatonin (1mg/ml, 10ml/kg) 10 min before the establishment of animal model, and control group was injected with same volume normal saline. The presence of mtDNA deletion was examined using nested polymearse chain reaction (nPCR), the sequence of missing fragment was detected by gene sequencing technology, the mtDNA4834 deletion was quantitated by real-time quantitative PCR, and the contents of MDA and SOD were measured respectively by thiobarbituric acid (TAB) and xanthine oxidation (XTO).【Results】: There no mtDNA4834 deletion was detected in normal group and sham-operated group by nPCR, and the total frequence of mtDNA4834 deletion in cerebral hemorrhage group was 54%, and the deletion frequence was in a time- dependent relationship, the deletion frequence increased along with the increase of the bleeding time. The real-time PCR results showed that mtDNA4834 deletion rate in cerebral hemorrhage group had statistically significant difference compare with the normal group and the corresponding sham group (P <0.05). And mtDNA4834 deletion rate tended to increasing along with the increase of the bleeding time. The activity of SOD reduced significantly after ICH. It has declined at 12h, up to a minimum at 1d, then increased gradually, and was still lower than normal group and sham-operated group. The content of MDA changes in the opposite―increased significantly after ICH. In the interference experiment, mtDNA4834 deletion rate was evidently lower than control group after intervention by melatonin (P <0.05). The activity of SOD increased significantly after intervention by melatonin, peaked at 1d, and then lowered gradually. The content of MDA changes in the opposite― reduced significantly after intervention by melatonin.【Conclusions】: Intracerebral hemorrhage started the damage of mtDNA4834 deletion, and it associated with the increase in free radical damage; mtDNA4834 deletion might furhter aggrevate tardive nerve cell injury after intracerebral hemorrhage. Melatonin have a inhibiting effect on mtDNA in intracerebral hemorrhage, and the mechanism related to the reduction in oxygen free radicals and the inhibition of lipid peroxidation.