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AIM: To explore whether free radicals participate in cerebral ischemic tolerance and the up-regula-tion of p38 MAPK and ERK signaling pathways in rats induced by limb ischemic preconditioning (LIP). METHODS: A total of 128 Wistar rats with permanent occlusion of bilateral vertebral arteries were randomly divided into sham group (n=16), cerebral ischemia (CI) group (n=16), LIP+CI group (n=16), DMTU (a free radical scavenger)+LIP+CI group (n=64) and DMTU+sham group (n=16). Six rats in each group were used to observe the delayed neuronal death (DND) in hippocampal CA1 region by thionin staining at 7 d after the end of operation. Other 10 rats in each group were used to de-tect the expression of p38 MAPK and ERK in hippocampal CA1 region by immunohistochemistry and Western blot. RE-SULTS: Lethal CI resulted in obvious DND in hippocampal CA1 region. However, LIP reversed the above injurious changes, represented by the decrease in histological grade and the increase in neuronal density compared with CI group (P<0. 01). Moreover, LIP significantly up-regulated the expression of p38 MAPK and ERK in hippocampal CA1 region com-pared with CI group (P<0. 01). Administration of free radical scavenger DMTU via femoral vein before LIP partially re-versed the neuroprotective effect of LIP, and blocked the up-regulation of p38 MAPK and ERK expression in hippocampal CA1 region in rats compared with LIP+CI group (P<0. 01). CONCLUSION: Free radicals are involved in the neuropro-tection and up-regulation of p38 MAPK and ERK expression induced by LIP in rats.
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Objective To observe the effects and regulatory mechanism of rotavirus infection on the expression and bioactivity of Na+/H+exchanger 3 (NHE3) on Caco-2 cells. Methods A cell model of Caco-2 cells expressing NHE3 was constructed. Four groups were set up,which were control(CTL) group, rotavirus(RV) infection group, Cdc42 inhibitor (Pirl-1) group and Pirl-1+RV group. Bioactivity and ex-pression of NHE3 on the surface of Caco-2 cells were determined by BCECF-AM and biotinylation method, respectively. Expression of Cdc42 protein was measured by Western blot. Co-immunoprecipitation was per-formed to detect the interaction between NHE3 and Cdc42. Results Compared with the CTL group,RV in-fection significantly inhibited the bioactivity and expression of NHE3 on Caco-2 cells. These inhibitory effects were antagonized by Pirl-1. Moreover,RV infection enhanced the expression of Cdc42 protein and promoted the interaction between NHE3 and Cdc42, which were also antagonized by Pirl-1. Conclusion RV infec-tion might regulate the expression and bioactivity of NHE3 through Cdc42-dependent endocytosis pathway.
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Objective To investigate the pattern of the cerebral white matter lesions in patients with mild and moderate Alzheimer's disease(AD)and healthy controls using proton magnetic resonance spectroscopy(~1H-MRS)and diffusion tensor imaging(DTI).Methods Twenty AD patients and Twenty healthy controls were recrnited.All subjects underwent clinical examination,neuropsychological assessment.The quantitative analysis of N-acetylaspartate(NAA),myoinositol(mI),Chotine(Cho)and Creatine(Cr)resonance signals in region of interests(ROIs)located in the paraventricular white matter region bilaterally were measured.Ratios of NAA/Cr,mI/Cr and Cho/Cr were calculated in two groups.In addition,conventional MRI and DTI scanning were received,fractional anisotropy(FA)and mean diffusivity(MD)values of white matter in the same regions were measured respectively.Results No significant difference between two groups were observed in NAA/Cr ratio(P＞0.05).A significantly increased mI/Cr and Cho/Cr were found in AD patients than in controls(P＜0.05).FA and MD values in AD patients were 0.470±0.082 and 0.771±0.099,and in controls were 0.539±0.068 and 0.691±0.064,respectively.FA value decreased significantly in AD patients(P＜0.05),M D value increased significantly in AD patients(P＜0.05).After controlling for age-related,partial correlation analysis revealed a negtive correlation between mI/Cr and FA value in the patients with AD(P＜0.05).No correlation between mI/Cr and MD was found(P＞0.05).Conclusion The results suggest that not only the gray matter is injured,but also the white matter is abnormal in AD patients.Combining ~1H-MRS with DTI alterations could provide the valuable informations about white matter lesions in AD patients.
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AIM: To explore the role of NO/ inducible nitric oxide synthase (iNOS) in the metabotromi glutamate receptor 2/3C (mGluR2/3) mediated-brain ischemic tolerance induced by cerebral ischemic preconditioning (CIP), and to observe the influences of α-methyl- (4-tetrazolyl- phenyl) glycine (MTPG), an antagonist of mGluR2/3, on the expression of iNOS during the induction of brain ischemic tolerance. METHODS: Thirty-six Sprague-Dawley rats were subjected to four vessel occluding global brain ischemic model. Thionin staining and immunohistochemistry were used for neuropathological evaluation and assay of iNOS expression in the hippocampal CA1 subregion of the rats. RESULTS: In the sham group, weak expression of iNOS was detected. The expression of iNOS in the CIP and CIP+ischemic insult groups were increased significantly compared with that in the sham group. Administration of MTPG via lateral cerebral ventricle 20 min before CIP blocked the up-regulation of iNOS induced by CIP, but had no influence on the pyramidal neuron survival. However, in the MTPG+CIP+ischemic insult group, the expression of iNOS was extremely intensive compared to that in CIP and MTPG+CIP groups. Importantly, this up-regulation was accompanied with obvious delayed neuronal death. CONCLUSION: NO/iNOS pathway plays an important role in the process of mGluR2/3 mediated-brain ischemic tolerance induced by CIP.
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BACKGROUND: Metabotropic glutamate receptor(mGluR) is G-protein coupled membrane receptors, which participate in various physiology or pathology process in brain, but how it induce brain ischemic tolerance(BIT)is unclear.OBJECTIVE: To study roles of mGluR2/3 and mGluR1/5 in the BIT induction.DESIGN: Randomized controlled study based on experimental animals.SETTING: Neurological department of provincial hospital and pathophysiological department of basic institute in a university.MATERIALS: The study was conducted at the Pathophysiological Department, Institute of Basic Medicine, Hebei Medical University from May 2002 to May 2003. Totally 64 healthy male SD rats were selected from the Experimental Animal Center of Hebei Medical University. Glial fibrillary acidic protein (GFAP) antibody, MTPG and(s)-4C3HPG were got from Sigma Company.INTERVENTIONS: 4 vessel occlusion(4VO) brain ischemic models in rats stained with thionine staining and GFAP immunohistochemistry staining. were used. Sixty-four rats, of which bilateral vertebral arteries were occluded permanently by electrocautery, were divided into the following 8groups: sham operation group, cerebral ischemic preconditioning(CIP)group, ischemic insult group; BIT group; MTPG + sham operation group;MTPG+BIT group; MTPG+ischemia group and(s) -4C3HPG+BIT coup. All the rats were killed 7 days after the operation or the final ischemic treatment. Cerebral sections were selected and stained with thionine staining and GFAP immunohistochemistry staining.MAIN OUTCOME MEASURE: The changes of the morphologic hippocampal pyramidal cell and GFAP expression of astrocyte.RESULTS: ① The 8 minutes ischemic insult increased the histological grade(HG) in CA1 area, decreased the pyramidal neuronal density(ND)and increased the expression of GFAP significantly( P ＜ 0.05) . ② The above changes were not observed in the BIT group, indicating that the CIP could protect pyramidal neurons against the 8-minute ischemic insult. ③The protective effects of the CIP were blocked by MTPG or(s)-4C3HPG, as manifested by significant increases in HG and decreases in ND in the groups of MTPG + BIT, MTPG + ischemia and(s)-4C3HPG + BIT( P ＜ 0.05).CONCLUSION: MTPG or (s) -4C3HPG could block the induction of BIT induced by CIP, but mGluR2/3 or mGluR1/5 could participate in the induction of BIT by which protect effect of mGluR is further induced.
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AIM: To explore the role of NO in the induction of brain ischemic tolerance (BIT) by observing changes of NOS activity and NO_2-/NO_3- content following a transient cerebral ischemia. METHODS: The rat 4-vessel occluding brain ischemic model was used. 140 male Wistar rats were divided into sham, cerebral ischemic preconditioning (CIP), ischemic insult and CIP+ischemic insult groups. An occlusion of the 4 vessels for 3 min was normally used as CIP, and a relative long one for 10 min was used as ischemic insult. When CIP was followed by ischemic insult, the interval between them was 3 d. The CA1 region of the hippocampus of rats was dissected out at 0 h, 2 h, 16 h, 24 h, 36 h, 72 h and 7 d after the last time of ischemia to assay its NOS activity and NO_2-/NO_3- content. RESULTS: The NOS activity and NO_2-/NO_3- content began to increase at 16 h, peaked at 24 h and decreased to basal level at 36 h of reperfusion after CIP. The duration of the up-regulation of NOS activity and NO_2-/NO_3- content was much shorter than that of BIT, which usually takes place 1-7 d after CIP. The pattern of upregulation of the NOS activity and NO_2-/NO_3- content was similar to the CIP group, but the maximum (24 h) was much more than that in CIP group (P