| Objective: Neonatal hypoxic-ischemic brain injury is an important cause of mortality in neonatal period and permanent neurological dysfunc- tion in the children. Recently there is competitive evidence indicates that inflammation and apoptosis play an critical role in the pathogenesis of neonatal hypoxic-ischemic brain injury. Nuclear factor-κB(NF-κB) is an important transcription factor and expressed ubiquitously in eukaryotic cells. NF-κB has been implicated in many important pathophysiological mechanisms including inflammation, immune responses,cell proliferation, differentiation and apoptosis via modulating gene transcription and expre- ssion. Thus it plays a pivotal role in the process of initiation and deve- lopment in many clinical conditions and has been a new target for novel drug development. NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) was recently found to be neuroprotective in various models of brain ischemia in adult rats,but whether it has neuroprotection in neonatal rats subjected to hypoxia-ischemia(HI) is still unclear. Thus, in the present study we used a 7-day-old neonatal rat hypoxic-ischemic brain damage model to identify the roles of NF-κB in hypoxic-ischemic brain damage by examining protein expression of nuclear factor-κappaBp65 and neuronal apoptosis in cortex and hippocampal CA1 in left hemisphere after HI at different time points,A secondary aim was to investigate whether PDTC pretreatment has beneficial effect on neonatal hypoxic-ischemic brain injury and its mechanisms. Methods: Seventy–two 7-day–old newborn healthy SD rat pups were randomly assigned into sham operated group, HIBD group, PDTC pretreat- ment group(n=24 each). Pups in each group were randomly divided into four sub-groups sacrificed at 1/6/12/24h after HI(n=6 each). HI was i nduced by ligati ng the le ft c ommo n carotid artery, r ecovere d for 2h,t he n subjecte d t o 8% oxygen hypoxia for 2h. Pups in sham operated group were not subjected to HI .Rups in PDTC pretreatment group were injected intraperitoneally with PDTC solution 1h before HI (50ug/g body weight), pups in the sham operated and HIBD groups were injected with same volume 0.9% NaCl solution .To detect brain histopathological changes using Haematoxylin-Eosin staining and degenerating neurons with Nissl staining;Immonohischemistry was used to detect protein expression of NF-κBP65;TUNEL cell apoptosis situ detection was applied to detect apoptotic neurones .Results: (1) Compared with Sham operated group at same time point after HI, NF-κBP65 and apoptotic positive cells in cortex and hippocampal CA1 in HIBD group were significantly increased (P<0.01 or P<0.001);(2) Compared with HIBD group at same time point after HI, NF-κBP65 and apoptotic positive cells in cortex and hippocampal CA1 in PDTC pretreat- ment group were significantly reduced(P<0.05 or P<0.01); (3)In HIBD group, compared with HI 1h sub-group,the number NF-κBP65 and apoptotic positive cells in cortex and hippocampal CA1 in HI 6h,12h, 24h sub-groups was significant(P<0.05); (4)The linear correlation analysis demonstrated that the number of apoptotic neuronal cells was positively correlated to the number of NF-κBP65 positive cell in HIBD group (r=0.841,P<0.01).Conclusion:(1) Hypoxia-ischemia stimulus induced activation of NF-κB; (2) Activated NF-κB was related with neuronal death mechanism; (3) PDTC pretreatment had neuroprotection in hypoxic-ischemic brain injury, the mechanism was related to inhibiting activation of nuclear factor-κB.
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