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Objective Nrf2 is an important neuroprotective factor and the ubiquitin proteasome system ( UPS) , as a highly specific intracellular protein degradation pathway, plays an important role in maintaining gene and protein functions.This paper pres-ents a preliminary study on the relationship between Nrf2 and the ubiquitin proteasome system in the mouse model of traumatic brain in-jury ( TBI) . Methods Forty-two healthy male ICR mice were randomly divided into three groups: control, TBI +sulforaphane ( SFN) and TBI+vehicle, and 12 Nrf2-knockout mice were included in the TBI+Nrf2 -/-group.The animals of the TBI+SFN group were treated with SFN while those of the TBI+vehicle group with the same volume of 10%corn oil at 5 minutes after TBI.At 24 hours after TBI, brain samples were collected from the mice for determining the Nrf2 expression and ubiquitinated protein content by Western blot and the changes in the Nrf2 and ubiquitinated proteins were observed by immunohistochemistry and electron microscopy. Results Compared with the controls, the mice in the TBI+vehicle group showed significantly increased expressions of Nrf2 ( 0.09 ± 0.02 vs 0.66 ±0.09, P<0.05) and ubiquitinated proteins (3.27 ± 0.21 vs 10.58 ±0.75, P<0.05).In comparison with animals in the TBI+vehicle group, those in the TBI+SFN group exhibited a signifi-cant increase in the Nrf2 protein level (0.66 ±0.09 vs 1.22 ±0.14, P<0.05) but a decrease in the ubiquitinated protein level (10.58 ±0.75 vs 6.97 ±0.86, P<0.05), and those in the TBI+Nrf2 -/-group showed a markedly decreased expression of the Nrf2 protein (0.66 ±0.09 vs 0.17 ±0.02, P<0.05) but increased expression of the ubiquitinated protein (10.58 ±0.75 vs 14.35 ± 0.65, P<0.05).Similar results were observed by immunohistochemistry and electron microscopy. Conclusion Nrf2 played a neu-roprotective role in the mouse model of traumatic brain injury by regulating the ubiquitin proteasome system.
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Objective The prognosis of traumatic brain injury is closely associated with the apoptosis of neural cells .This study investigated the anti-apoptosis effect of alpha lipoic acid (α-LA) and its possible mechanism in the mouse model of traumatic brain injury. Methods Seventy-two healthy male ICR mice were randomly divided into four groups of 18 each:sham operation +vehicle, sham operation +α-LA, trauma +vehicle, and trauma +α-LA.The model of traumatic brain injury was made by weight-dropping.The animals in the α-LA groups were treated with intragastric α-LA at 30 minutes after surgery, while those in the vehicle groups with oral dimethyl sulfoxide in corn oil .At 48 hours after treatment , brain samples were collected from the mice for determining brain edema , measuring the expressions of cytochrome c , Bcl-2-associated X protein ( Bax ) , and caspase-3 in the mitochondria and cytosol of the brain tissue by Western blot and immunohistochemistry respectively , and detecting the survival of the neurons and apoptosis of neural cells in the cortical area by Nissl staining and TUNEL , re-spectively. Results The brain water volume , caspase-3 expres-sion, and neural cell apoptosis were markedly higher while the neuron survival remarkably lower in the trauma +vehicle group than in the sham operation +vehicle and sham operation +α-LA groups ( P<0.01).Compared with the mice in the trauma +vehicle group, those in the trauma +α-LA group showed significantly reduced proportion of water in the brain tissue ([79.89 ±0.55] vs [81.71 ± 0.66]%, P<0.05), expression of caspase-3 ([58.40 ±7.31] vs [47.42 ±7.74]%, P<0.05), and apoptosis of neural cells ([59.63 ±8.61] vs [44.86 ±7.32]%, P <0.05), but increased survival rate of neurons ([44.45 ±10.56] vs [57.46 ± 11.01]%, P<0.05).The expression of cytochrome c in the mitochondria was remarkably decreased and that of Bax markedly in -creased in the trauma +vehicle than in the sham operation +vehicle and sham operation +α-LA groups (P<0.01). Conclusion Alpha lipoic acid has a protective effect against traumatic brain injury in mice , probably by inhibiting the apoptosis of neural cells through the mitochondrial pathway .
RESUMO
Objective Subarachnoid hemorrhage ( SAH) is a devastating disease with high fatality and morbidity and micro-glia/macrophage ( M/M) plays a vital role in SAH brain injury with complicated pathophysiological mechanism .This study was to ob-serve the effect of Nrf2 deficiency on M/M activation and M1 polarization after subarachnoid hemorrhage in mice . Meth ods We col-lected 70 wild-type ( WT) ICR mice and 35 Nrf2-knockout ( KO) mice to establish the SAH model by injecting fresh autologous blood into pre-chiasmatic cistern.WT mice were arranged into four groups: sham operation group, post operative day 1 (POD1) group, POD3 group and POD5 group.Then WT mice and Nrf2 Nrf2-knockout mice were divided into sham operation WT group , sham opera-tion KO group, SAH WT group and SAH KO group.Western blotting (WB) and immunohistochemistry (IHC) were applied to observe the activation and proliferation of M/M after SAH on WT mice .Difference in activation and M 1 polarization were observed by detecting Iba1 expression in WB and CD 16/32 +Iba1 +cells in immunofluorescence between WT and KO mice . Results Gray scale values of Iba1 expression by WB in WT mice are 0.491 ±0.039, 0.657 ± 0.069, 0.930 ±0.046 and 0.926 ±0.046;average optical intensity values of Iba1 expression by IHC in WT mice are 0.412 ±0.122, 0.625 ±0.135, 0.963 ±0.213 and 0.978 ±0.224.The data indica-ted that Iba1 expression increased in SAH KO group in comparison to SAH WT group on 1, 3, 5 day after SAH (P<0.05).Moreover, Nrf2 deficiency promoted the activation and polarization of M /M by increased Iba1 protein expression and CD16/32 +Iba1 +cells after SAH ( P<0.05). Conclusion SAH induces M/M activation and proliferation in mice, and Nrf2 deficiency promotes the activa-tion, proliferation and M1 polarization after SAH .
