Distribution of ferritin in the rat hippocampus after kainate-induced neuronal injury

A gradual increase in iron occurs in the lesioned hippocampus after neuronal injury induced by the excitotoxin kainate, and the present study was carried out to investigate whether this increase in iron might be associated with changes in expression of the iron binding protein, ferritin. An increase in ferritin immunoreactivity was observed in glial cells of the hippocampus, as early as three days after intracerebroventricular injections of kainate. The number of ferritin positive cells peaked four weeks after the kainate injection, and decreased eight and twelve weeks after injection. They were found to be mostly microglia and oligodendrocytes by double immunofluorescence labeling with glial markers. A number of ferritin-labeled endothelial cells were also observed via electron microscopy. The decline in ferritin immunoreactivity four weeks after the injection of kainate is accompanied by an increase in the number of ferric and ferrous iron positive cells in the lesioned tissue. A substantial non-overlap between ferritin and iron-containing cells was observed. In particular, spherical ferric or ferrous iron-laden cells in the degenerating hippocampus were unlabeled for ferritin for long time periods after the kainate injection. An increase in iron, together with a reduced expression of iron binding proteins such as ferritin at long time intervals after kainate lesions, could result in a relative decrease in ferritin-induced ferroxidase activity and the presence of some of the iron in the ferrous form. It is postulated that this may contribute to chronic neuronal injury, following acute kainate-induced neurodegeneration.     

Iron overload induces changes of pancreatic and duodenal divalent metal transporter 1 and prohepcidin expression in mice

It is well known that the iron content of the body is tightly regulated. Iron excess induces adaptive changes that are differentially regulated in each tissue. The pancreas is particularly susceptible to iron-related disorders. We studied the expression and regulation of key iron proteins in the pancreas, duodenum and liver, using an animal model of iron overload (female CF1 mice injected i.p. with iron saccharate, colloidal iron form). Divalent metal transporter 1, prohepcidin and ferritin (pancreas, duodenum, liver) were assessed by immunohistochemistry; divalent metal transporter 1 (pancreas, duodenum) by Western blot. In the iron overloaded mice, prohepcidin expression increased in islets of Langerhans and hepatocytes, and divalent metal transporter 1 expression decreased in cells of islets and in enterocytes. In the iron overloaded mice, ferritin expression decreased in islets of Langerhans and increased in acinar cells; hemosiderin was localized in connective tissue cells. The inverse relationship between divalent metal transporter 1 and prohepcidin may indicate a negative regulation by hepcidin, and hence reduction of iron stores in islets of Langerhans. Our data showed that in iron overloaded mice model, induced by colloidal iron form, a coordinated expression of key iron proteins in the pancreas, duodenum and liver may occur. Further research will be necessary to determine the adaptive responses induced by iron in the pancreas.     

铁转运相关蛋白在肌萎缩性侧索硬化症转基因鼠脊髓中的表达变化

目的探讨肌萎缩性侧索硬化症(ALS)转基因鼠脊髓内铁转运相关蛋白表达变化与铁稳态失衡的关联。方法选取h SOD1G93A转基因鼠(ALS鼠)和同窝野生型鼠(WT鼠),分别于生后70、95和122 d分离脊髓,每时间点每组各9只实验动物。Western blotting检测脊髓组织内铁转运蛋白二价金属转运蛋白-1(DMT1)、铁转运蛋白-1(FPN1)及调节蛋白铁调节蛋白-1(IRP1)的表达;免疫荧光双重标记检测脊髓腰段前角内细胞共定位情况。结果 Western blotting显示,与WT鼠比较,各时间点ALS鼠脊髓内DMT1表达均显著降低(P<0.05,P<0.01);70 d FPN1表达升高(P<0.05),95 d和122 d表达下降(P<0.01); 95 d、122 d IRP1表达降低(P<0.01)。免疫荧光双重标记显示,在70 d WT鼠和ALS鼠腰段脊髓中DMT1主要与β-微管蛋白Ⅲ(β-tubulinⅢ)共表达。与WT组相比,95 d ALS鼠脊髓腰段前角神经元内DMT1免疫反应强,而FPN1荧光强度减弱。随疾病进展,DMT1、FP...     

脑缺血诱导大鼠皮层和海马二价金属离子转运体1表达增加的研究

目的:探讨脑缺血对大鼠皮层、海马二价金属离子转运体1(DMT1)表达的影响。方法:雄性Wistar大鼠随机分为脑缺血1、3、7、28 d和假手术组。结扎双侧颈总动脉建立脑缺血模型组,假手术组仅分离双侧颈总动脉但不结扎。采用RT-PCR测定DMT1+/-IRE mRNA的表达;采用免疫组化染色测定大鼠皮层及海马组织DMT1的表达。结果:大鼠皮层和海马DMT1+/-IRE mRNA的表达随缺血时间的延长逐渐增加。与假手术组比较,皮层DMT1+/-IRE mRNA的表达在缺血1、3 d时无差异(P>0.05);缺血7 d时表达增加(P<0.01),缺血28d时增加更明显(P<0.01)。海马DMT1-IRE mRNA表达除在缺血1 d时与假手术组无差异外(P>0.05),其余时间点DMT1+/-IRE mRNA表达均高于假手术组(P<0.01)。随缺血时间的延长,大鼠皮层、海马的锥体细胞、颗粒细胞及血管内皮细胞DMT1的表达逐渐增加。DMT1的表达除缺血1 d组与假手术组无差别外(P>0.05),其余各组均高于假手术组(P<0.05)。结论:脑缺血可诱导大鼠皮层及海马DMT1表达升高,DMT1表达的改变可能参与了脑缺血引起大鼠脑铁含量升高及神经元铁沉积过程。     

The toxicity of lead to Desulfovibrio desulfuricans G20 in the presence of goethite and quartz

An aqueous mixture of goethite, quartz, and lead chloride (PbCl₂) was treated with the sulfate‐reducing bacterium, Desulfovibrio desulfuricans G20 (D. desulfuricans G20), in a medium specifically designed to assess metal toxicity. In the presence of 26 μM of soluble Pb, together with the goethite and quartz, D. desulfuricans G20 grew after a lag time of 5 days compared to 2 days in Pb‐, goethite‐, and quartz‐free treatments. In the absence of goethite and quartz, however, with 26 μM soluble Pb, no measurable growth was observed. Results showed that D. desulfuricans G20 first removed Pb from solutions then growth began resulting in black precipitates of Pb and iron sulfides. Transmission electron microscopic analyses of thin sections of D. desulfuricans G20 treated with 10 μM PbCl₂ in goethite‐ and quartz‐free treatment showed the presence of a dense deposit of lead sulfide precipitates both in the periplasm and cytoplasm. However, thin sections of D. desulfuricans G20 treated with goethite, quartz, and PbCl₂ (26 μM soluble Pb) showed the presence of a dense deposit of iron sulfide precipitates both in the periplasm and cytoplasm. Energy‐dispersive X‐ray spectroscopy, selected area electron diffraction patterns, or X‐ray diffraction analyses confirmed the structure of precipitated Pb inside the cell as galena (PbS) in goethite‐ and quartz‐free treatments, and iron sulfides in treatments with goethite, quartz, and PbCl₂. Overall results suggest that even at the same soluble Pb concentration (26 μM), in the presence of goethite and quartz, apparent Pb toxicity to D. desulfuricans G20 decreased significantly. Further, accumulation of lead/iron sulfides inside D. desulfuricans G20 cells depended on the presence of goethite and quartz. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Increased expression of cysteinyl leukotriene receptor-1 in the brain mediates neuronal damage and astrogliosis after focal cerebral ischemia in rats

Cysteinyl leukotrienes are potent pro-inflammatory mediators. Cysteinyl leukotriene receptor 1 is one of the two cysteinyl leukotriene receptors cloned. We recently reported that cysteinyl leukotriene receptor 1 antagonists protected against cerebral ischemic injury, and an inducible expression of cysteinyl leukotriene receptor 1 was found in neuron- and glial-appearing cells after traumatic injury in human brain. To determine the role of cysteinyl leukotriene receptor 1 in ischemic brain injury, we investigated the temporal and spatial profile of cysteinyl leukotriene receptor 1 expression in rat brain from 3 h to 14 days after 30 min of middle cerebral artery occlusion, and observed the effect of pranlukast, a cysteinyl leukotriene receptor 1 antagonist, on the ischemic injury. We found that cysteinyl leukotriene receptor 1 mRNA expression was up-regulated in the ischemic core both 3-12 h and 7-14 days, and in the boundary zone 7-14 days after reperfusion. In the ischemic core, cysteinyl leukotriene receptor 1 was primarily localized in neurons 24 h, and in macrophage/microglia 14 days after reperfusion; while in the boundary zone it was localized in proliferated astrocytes 14 days after reperfusion. Pranlukast attenuated neurological deficits, reduced infarct volume and ameliorated neuron loss in the ischemic core 24 h after reperfusion; it reduced infarct volume, ameliorated neuron loss and inhibited astrocyte proliferation in the boundary zone 14 days after reperfusion. Thus, we conclude that cysteinyl leukotriene receptor 1 mediates acute neuronal damage and subacute/chronic astrogliosis after focal cerebral ischemia.     

脑损伤后热休克蛋白70及热休克因子Ⅰ基因转录的实验研究

目的　为了解脑损伤后应激基因转录的状况。方法　采用RT PCR对伤后脑组织HSP70 、HSF1mRNA的数量进行测定。结果　在脑损伤 15min后脑干HSP70 、HSF1mRNA水平显著升高 ,在损伤后迅速死亡的致死损伤组的鼠脑中HSP70 、HSF1mRNA水平亦显著升高。结论　应激基因的转录水平在脑损伤后明显提高 ,脑应激蛋白合成增强 ,参与损伤与修复过程。同时由于HSP70 、HSF1mRNA对脑损伤的迅速反应能力 ,使之成为观察脑损伤的灵敏指     

Pyruvate dehydrogenase phosphatase1 mRNA expression is divergently and dynamically regulated between rat cerebral cortex, hippocampus and thalamus after traumatic brain injury: A potential biomarker of TBI-induced hyper- and hypo-glycaemia and neuronal vulnerability

Cerebral pyruvate depletion and lactate acidosis are common metabolic characteristics of patients with traumatic brain injury (TBI) and are associated with poor prognosis. Pyruvate dehydrogenase (PDH) is the rate-limiting enzyme coupling glycolysis to mitochondrial tricarboxylic acid (TCA) cycle. Brain PDH activity is regulated by its phosphorylation status and other effectors. Phosphorylation of PDH E1α1 subunit by PDH kinase inhibits PDH activity while dephosphorylation of phosphorylated PDHE1α1 by PDH phosphatase (PDP1) restores PDH activity. In situ hybridization showed that PDP1 mRNA is highly expressed in the cerebral cortex, hippocampus and thalamus of rat. Controlled cortical impact (CCI) induced a significant increase in PDP1 mRNA expression in ipsilateral cerebral cortex at 4h (P<0.05) and 24h post CCI (P<0.01) that returned to basal level 72h post CCI. PDP1 mRNA level increased transiently in ipsilateral hippocampal dentate gyrus and CA1-3 subfields 4h post CCI (P<0.01) but decreased significantly 24h and 72h (P<0.01) post CCI, coinciding with a marked increase in neuronal apoptosis in ipsilateral hippocampus 24h post CCI. PDP1 mRNA expression in thalamus and other subcortical regions decreased persistently post CCI. Contralateral CCI and craniotomy showed similar effects on PDP1 mRNA expression as ipsilateral CCI. Because GFAP mRNA expression was induced in brain regions where PDP1 expression was altered, further study should determine the potential relationship between astrocyte activation, PDP1 alteration, and pyruvate metabolism following TBI.     

Elucidating the role of 5-HT(1A) and 5-HT(7) receptors on 8-OH-DPAT-induced behavioral recovery after experimental traumatic brain injury

8-OH-DPAT is a 5-HT(1A/7) receptor agonist that enhances behavioral recovery after traumatic brain injury (TBI). This study is a first attempt to decipher whether the benefits induced by 8-OH-DPAT after TBI are mediated by 5-HT(1A) or 5-HT(7) receptors. A single i.p. injection of 8-OH-DPAT (0.5 mg/kg) alone or co-administered with either the 5-HT(1A) or 5-HT(7) receptor antagonists WAY 100635 (0.5 mg/kg) or SB 269970 HCl (2.0 mg/kg), respectively, or vehicle control (1.0 mL/kg) was given 15 min after cortical impact or sham injury. Function was assessed by established motor and cognitive tests. No difference in motor performance was observed among the TBI groups. Spatial acquisition was enhanced, relative to vehicle controls, by 8-OH-DPAT alone and when co-administered with WAY 100635, but not when combined with SB 269970 HCl. These data imply that 5-HT(1A) receptor antagonism does not abate the 8-OH-DPAT-induced cognitive benefits, but 5-HT(7) receptor antagonism does, which suggests that the 8-OH-DPAT-induced benefits in this single administration paradigm may be mediated more by 5-HT(7) versus 5-HT(1A) receptors. Evaluation of a specific 5-HT(7) receptor agonist will further elucidate the contribution of 5-HT(1A) and 5-HT(7) receptors on behavioral recovery conferred by acute 8-OH-DPAT treatment after TBI.