Postischemic Alterations of BDNF, NGF, HSP 70 and Ubiquitin Immunoreactivity in the Gerbil Hippocampus: Pharmacological Approach

Proprotein convertase 1/3-mediated down-regulation of brain-derived neurotrophic factor in cortical neurons induced by oxygen-glucose deprivation

Brain-derived neurotrophic factor (BDNF) has robust effects on synaptogenesis, neuronal differentiation and synaptic transmission and plasticity. The maturation of BDNF is a complex process. Proprotein convertase 1/3 (PC1/3) has a key role in the cleavage of protein precursors that are directed to regulated secretory pathways; however, it is not clear whether PC1/3 mediates the change in BDNF levels caused by ischemia. To clarify the role of PC1/3 in BDNF maturation in ischemic cortical neurons, primary cortical neurons from fetal rats were cultured in a humidified environment of 95% N₂ and 5% CO₂ in a glucose-free Dulbecco’s modified Eagle’s medium at 37°C for 3 hours. Enzyme-linked immunosorbent assays and western blotting showed that after oxygen-glucose deprivation, the secreted and intracellular levels of BDNF were significantly reduced and the intracellular level of PC1/3 was decreased. Transient transfection of cortical neurons with a PC1/3 overexpression plasmid followed by oxygen-glucose deprivation resulted in increased PC1/3 levels and increased BDNF levels. When levels of the BDNF precursor protein were reduced, the concentration of BDNF in the culture medium was increased. These results indicate that PC1/3 cleavage of BDNF is critical for the conversion of pro-BDNF in rat cortical neurons during ischemia. The study was approved by the Animal Ethics Committee of Wuhan University School of Basic Medical Sciences.

Heat shock protein 70 gene polymorphisms are associated with paranoid schizophrenia in the Polish population

HSP70 genes have been considered as promising schizophrenia candidate genes based on their protective role in the central nervous system under stress conditions. In this study, we analyzed the potential implication of HSPA1A +190G/C, HSPA1B +1267A/G, and HSPA1L +2437T/C polymorphisms in the susceptibility to paranoid schizophrenia in a homogenous Caucasian Polish population. In addition, we investigated the association of the polymorphisms with the clinical variables of the disease. Two hundred and three patients with paranoid schizophrenia and 243 healthy controls were enrolled in the study. Polymorphisms of HSPA1A, -1B, and -1L genes were genotyped using the PCR-RFLP technique. Analyses were conducted in entire groups and in subgroups that were stratified according to gender. There were significant differences in the genotype and allele frequencies of HSPA1A polymorphism between the patients and controls. The +190CC genotype and +190C allele were over-represented in the patients and significantly increased the risk for developing schizophrenia (OR = 3.45 and OR = 1.61, respectively). Interestingly, such a risk was higher for females with the +190CC genotype than for males with the +190CC genotype (OR = 5.78 vs. OR = 2.76). We also identified the CGT haplotype as a risk haplotype for schizophrenia and demonstrated the effects of HSPA1A and HSPA1B genotypes on the psychopathology and age of onset. Our study provided the first evidence that the HSPA1A polymorphism may potentially increase the risk of developing paranoid schizophrenia. Further independent analyses in different populations to evaluate the role of gender are needed to replicate these results.

Therapeutic effect of nerve growth factor on cerebral infarction in dogs using the hemisphere anomalous volume ratio of diffusion-weighted magnetic resonance imaging

A model of focal cerebral ischemic infarction was established in dogs through middle cerebral artery occlusion of the right side. Thirty minutes after occlusion, models were injected with nerve growth factor adjacent to the infarct locus. The therapeutic effect of nerve growth factor against cerebral infarction was assessed using the hemisphere anomalous volume ratio, a quantitative index of diffusion-weighted MRI. At 6 hours, 24 hours, 7 days and 3 months after modeling, the hemisphere anomalous volume ratio was significantly reduced after treatment with nerve growth factor. Hematoxylin-eosin staining, immunohistochemistry, electron microscopy and neurological function scores showed that infarct defects were slightly reduced and neurological function significantly improved after nerve growth factor treatment. This result was consistent with diffusion-weighted MRI measurements. Experimental findings indicate that nerve growth factor can protect against cerebral infarction, and that the hemisphere anomalous volume ratio of diffusion-weighted MRI can be used to evaluate the therapeutic effect.

Comparison of glial activation in the hippocampal CA1 region between the young and adult gerbils after transient cerebral ischemia

It has been reported that young animals are less vulnerable to brain ischemia. In the present study, we compared gliosis in the hippocampal CA1 region of the young gerbil with those in the adult gerbil induced by 5 min of transient cerebral ischemia by immunohistochemistry and western blot for glial cells. We used male gerbils of postnatal month 1 (PM 1) as the young and PM 6 as the adult. Neuronal death in CA1 pyramidal neurons in the adult gerbil occurred at 4 days post-ischemia; the neuronal death in the young gerbil occurred at 7 days post-ischemia. The findings of glial changes in the young gerbil after ischemic damage were distinctively different from those in the adult gerbil. Glial fibrillary acidic protein-immunoreactive astrocytes, ionized calcium-binding adapter molecule (Iba-1), and isolectin B4-immunoreactive microglia in the ischemic CA1 region were activated much later in the young gerbil than in the adult gerbil. In brief, very less gliosis occurred in the hippocampal CA1 region of the young gerbil than in the adult gerbil after transient cerebral ischemia.

Assessment of neuroprotective effects of human umbilical cord blood mononuclear cell subpopulations in vitro and in vivo

Experimental transplantation of human umbilical cord blood (hUCB) mononuclear cells (MNCs) in rodent stroke models revealed the therapeutic potential of these cells. However, effective cells within the heterogeneous MNC population and their modes of action are still under discussion. MNCs and MNC fractions enriched (CD34(+)) or depleted (CD34(-)) for CD34-expressing stem/progenitor cells were isolated from hUCB. Cells were transplanted intravenously following middle cerebral artery occlusion in spontaneously hypertensive rats and directly or indirectly cocultivated with hippocampal slices previously subjected to oxygen and glucose deprivation. Application of saline solution or a human T-cell line served as controls. In vivo, MNCs, CD34(+) and CD34(-) cells reduced neurofunctional deficits and diminished lesion volume as determined by magnetic resonance imaging. MNCs were superior to other fractions. However, human cells could not be identified in brain tissue 29 days after stroke induction. Following direct application on postischemic hippocampal slices, MNCs reduced neural damage throughout a 3-day observation period. CD34(+) cells provided transient protection for 2 days. The CD34(-) fraction, in contrast to in vivo results, failed to reduce neural damage. Direct cocultivation of MNCs was superior to indirect cocultivation of equal cell numbers. Indirect application of up to 10-fold MNC concentrations enhanced neuroprotection to a level comparable to direct cocultivation. After direct application, MNCs migrated into the slices. Flow cytometric analysis of migrated cells revealed that the CD34(+) cells within MNCs were preferably attracted by damaged hippocampal tissue. Our study suggests that MNCs provide the most prominent neuroprotective effect, with CD34(+) cells seeming to be particularly involved in the protective action of MNCs. CD34(+) cells preferentially home to neural tissue in vitro, but are not superior concerning the overall effect, implying that there is another, still undiscovered, protective cell population. Furthermore, MNCs did not survive in the ischemic brain for longer periods without immunosuppression.

Expression of HSP70 in cerebral ischemia and neuroprotetive action of hypothermia and ketoprofen

Heat shock proteins (HSPs) are molecular chaperones that bind to other proteins to shepherd them across membranes and direct them to specific locations within a cell. Several injurious stimuli can induce Hsp70 expression, including ischemia. This study aimed to investigate the pattern of expression of protein (immunohistochemistry) and gene (real-time PCR) Hsp70 in experimental focal cerebral ischemia in rats by occlusion of the middle cerebral artery for 1 hour and the role of neuroprotection with hypothermia (H) and ketoprofen (K). The infarct volume was measured using morphometric analysis defined by triphenyl tetrazolium chloride. It was observed increases in the protein (p=0.0001) and gene (p=0.0001) Hsp70 receptor in the ischemic areas that were reduced by H (protein and gene: p<0.05), K (protein: p<0.001), and H+K (protein: p<0.01 and gene: p<0.05). The Hsp70 increases in the ischemic area suggests that the Hsp70-mediated neuroexcitotoxicity plays an important role in cell death and that the neuroprotective effect of both, H and K are directly involved with the Hsp70.

Tumorigenic development of induced pluripotent stem cells in ischemic mouse brain

Induced pluripotent stem (iPS) cells may provide cures for various neurological diseases. However, undifferentiated iPS cells have high tumorigenicity, and evaluation of the cells fates, especially in pathologic condition model, is needed. In this study, we demonstrated the effect of ischemic condition to undifferentiated iPS cells fates in a mouse model of transient middle cerebral artery occlusion (MCAO). Undifferentiated iPS cells were characterized with immunofluorescent staining. The iPS cells (5 × 10⁵) were injected into ipsilateral striatum and cortex after 24 h of MCAO. Histological analysis was performed from 3 to 28 days after cell transplantation. iPS cells in ischemic brain formed teratoma with higher probability (p < 0.05) and larger volume (p < 0.01) compared with those in intact brain. Among the four transcriptional factors to produce iPS cells, c-Myc, Oct3/4, and Sox2 strongly expressed in iPS-derived tumors in ischemic brain (p < 0.01). Additionally, expression of matrix metalloproteinase-9 (MMP-9) and phosphorylated vascular endothelial growth factor receptor2 (phospho-VEGFR2) were significantly increased in iPS-derived tumors in the ischemic brain (p < 0.05). These results suggest that the transcriptional factors might increase expression of MMP-9 and activate VEGFR2, promoting teratoma formation in the ischemic brain. We strongly propose that the safety of iPS cells should be evaluated not only in normal condition, but also in a pathologic, disease model.

Damage to neurons and oligodendrocytes in the hippocampal CA1 sector after transient focal ischemia in rats

Focal brain lesions such as transient focal cerebral ischemia can lead to neuronal damage in remote areas, including the ipsilateral substantia nigra and hippocampus, as well as in the ischemic core. In this study, we investigated acute changes in the ipsilateral hippocampus from 1 up to 7 days after 90 min of transient focal cerebral ischemia in rats, using anti-NeuN (neuronal nuclei), anti-Cu/Zn-superoxide dismutase (Cu/Zn-SOD), anti-Mn-SOD, anti-neuronal nitric oxide synthase (nNOS), anti-inducible NOS (iNOS), anti-glial fibrillary acidic protein (GFAP), anti-ionized calcium-binding adaptor molecule 1(Iba 1) and anti-2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) antibodies. In our western blot and histochemical analyses, present results show that transient focal cerebral ischemia in rats can cause a severe and acute damage of neurons and oligodendrocytes in the ipsilateral hippocampal CA1 sector. The present findings also demonstrate that the expression of iNOS produced by Iba 1-immunopositive microglia precedes the damage of neurons and oligodendrocytes in the ipsilateral hippocampal CA1 sector after transient focal cerebral ischemia. In contrast, our results suggest that increased reactive oxygen species (ROS) production during reperfusion cannot lead to damage of neurons and oligodendrocytes in the ipsilateral hippocampal CA1 sector after transient focal cerebral ischemia, because of an insufficient expression of Cu/Zn-SOD and Mn-SOD. Our double-labeled immunohistochemical study demonstrates that the overexpression of iNOS produced by Iba 1-immunopositive microglia may play a pivotal role in the damage of neurons and oligodendrocytes in the ipsilateral hippocampal CA1 sector at an acute stage after transient focal cerebral ischemia.

Morgana/CHP-1 is a novel chaperone able to protect cells from stress

Morgana/CHP-1 (CHORD containing protein-1) has been recently shown to be necessary for proper cell divisions. However, the presence of the protein in postmitotic tissues such as brain and striated muscle suggests that morgana/CHP-1 has additional cellular functions. Here we show that morgana/CHP-1 behaves like an HSP90 co-chaperone and possesses an independent molecular chaperone activity towards denatured proteins. The expression time profile of morgana/Chp-1 in NIH3T3 cells in response to heat stress is similar to that of Hsp70, a classical effector of Heat Shock Factor-1 mediated stress response. Moreover, overexpression of morgana/CHP-1 in NIH3T3 cells leads to the increased stress resistance of the cells. Interestingly, morgana/Chp-1 upregulation in response to transient global brain ischemia lasts longer in ischemia-resistant regions of the gerbil hippocampus than in vulnerable ones, suggesting the involvement of morgana/CHP-1 in natural protective mechanisms in vivo.

Long-term changes in the ipsilateral substantia nigra after transient focal cerebral ischaemia in rats

Transient focal cerebral ischaemia can cause neuronal damage in remote areas, including the ipsilateral thalamus and subsutantia nigra, as well as in the ischaemic core. In the present study, we investigated long-term changes in the ipsilateral substantia nigra from 1 up to 20 weeks after 90 min of transient focal cerebral ischaemia in rats, using tyrosine hydroxylase (TH), neuronal nuclei (NeuN), Iba-1, glial fibrillary acidic protein (GFAP) and brain-derived neurotrophic factor (BDNF) immunostaining. These results show that transient focal cerebral ischaemia in rats can cause a severe and prolonged neuronal damage in the ipsilateral striatum. Our results with TH and NeuN immunostaining also demonstrate that the atrophy of the ipsilateral substantia nigra after transient focal cerebral ischaemia was not static but progressive. Furthermore, our double-labelled immunohistochemical study suggests that BDNF released by GFAP-positive astrocytes may play a key role in the survival of dopaminergic neurones in the ipsilateral substantia nigra at the chronic stage after transient focal cerebral ischaemia, although the areas of the ipsilateral substantia nigra are decreased progressively after ischaemia. Thus our study provides further valuable information for the pathogenesis of neuronal damage after transient focal cerebral ischaemia.

Transplantation of placenta-derived mesenchymal stromal cells upon experimental stroke in rats

The beneficial effects of bone marrow-derived mesenchymal stromal cell (MSC) administration following experimental stroke have already been described. Despite several promising characteristics, placenta-derived MSC have not been used in models of focal ischemia. The aim of the current study is to investigate the impact of intravenously transplanted placenta-derived MSC on post-stroke recovery. Permanent occlusion of the middle cerebral artery was induced in spontaneously hypertensive rats. MSC were obtained from the human maternal or fetal placenta and intravenously administered after 24 h (single transplantation) or after 8 h and 24 h (dual transplantation). Sensorimotor deficits were quantified for 60 days using the beam walk test and the modified Neurological Severity Score system. Infarct volume was determined in vivo by means of magnetic resonance imaging on days 1, 8, 29 and 60. Astroglial reactivity was semiquantitatively ascertained within a small and a broad region adjacent to the lesion border. The double infusion of placental MSC was superior to single transplantation in the functional tests. However, a significant difference to the control group in all outcome parameters was observed only for maternally derived MSC. These findings suggest that placental tissue constitutes a promising source for experimental stroke therapies.

Effects of chronic low dose rotenone treatment on human microglial cells

Background

Exposure to toxins/chemicals is considered to be a significant risk factor in the pathogenesis of Parkinson's disease (PD); one putative chemical is the naturally occurring herbicide rotenone that is now used widely in establishing PD models. We, and others, have shown that chronic low dose rotenone treatment induces excessive accumulation of Reactive Oxygen Species (ROS), inclusion body formation and apoptosis in dopaminergic neurons of animal and human origin. Some studies have also suggested that microglia enhance the rotenone induced neurotoxicity. While the effects of rotenone on neurons are well established, there is little or no information available on the effect of rotenone on microglial cells, and especially cells of human origin. The aim of the present study was to investigate the effects of chronic low dose rotenone treatment on human microglial CHME-5 cells.

Methods

We have shown previously that rotenone induced inclusion body formation in human dopaminergic SH-SY5Y cells and therefore used these cells as a control for inclusion body formation in this study. SH-SY5Y and CHME-5 cells were treated with 5 nM rotenone for four weeks. At the end of week 4, both cell types were analysed for the presence of inclusion bodies, superoxide dismutases and cell activation (only in CHME-5 cells) using Haematoxylin and Eosin staining, immunocytochemical and western blotting methods. Levels of active caspases and ROS (both extra and intra cellular) were measured using biochemical methods.

Conclusion

The results suggest that chronic low dose rotenone treatment activates human microglia (cell line) in a manner similar to microglia of animal origin as shown by others. However human microglia release excessive amounts of ROS extracellularly, do not show excessive amounts of intracellular ROS and active caspases and most importantly do not show any protein aggregation or inclusion body formation. Human microglia appear to be resistant to rotenone (chronic, low dose) induced damage.

Ischemia-related changes in naive and mutant forms of ubiquitin and neuroprotective effects of ubiquitin in the hippocampus following experimental transient ischemic damage

Ubiquitin binds to short-lived proteins and denatured proteins produced by various forms of injury. The loss of ubiquitin leads to an accumulation of abnormal proteins and may affect cellular structure and function. The aim of the present study is to observe the chronological changes in ubiquitin naive form and its mutant form (ubiquitin(+1)) in the hippocampal CA1 region (CA1) after transient cerebral ischemia in gerbils. Delayed neuronal death in the CA1 was confirmed 4 days after ischemic insult with NeuN immunohistochemistry. Ubiquitin immunoreactivity and protein level in the CA1 were lowest at 12 h after ischemia/reperfusion; thereafter, they were increased with time. Ubiquitin(+1) immunoreactivity and protein levels in the CA1 were slightly decreased at 3 h after ischemia/reperfusion, and they were significantly increased 1 day after ischemia/reperfusion. In addition, ubiquitin and ubiquitin(+1) immunoreaction was expressed in astrocytes after delayed neuronal death in the ischemic CA1. To elucidate the protective effect of ubiquitin on ischemic damage, the animals were treated with ubiquitin (1.5 mg/kg body weight) intravenously via the femoral vein. Ubiquitin treatment significantly reduced ischemia-induced locomotor hyperactivity, neuronal death and reactive gliosis such as astrocytes and microglia. In addition, 5 days after ubiquitin treatment in the ischemic group, ubiquitin immunoreactivity was similar to that in the ubiquitin-treated sham group, however, ubiquitin(+1) immunoreactivity was higher than that in the ubiquitin-treated sham group. These findings indicate that the depletion of ubiquitin and the accumulation of ubiquitin(+1) in CA1 pyramidal neurons after transient cerebral ischemia may inhibit ubiquitin proteolytic pathway and this leads to delayed neuronal death of CA1 pyramidal neurons directly or indirectly after transient cerebral ischemia.

Age-related changes of NGF, BDNF, parvalbumin and neuronal nitric oxide synthase immunoreactivity in the mouse hippocampal CA1 sector

We investigated the age-related alterations in nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), parvalbumin and neuronal nitric oxide synthase (nNOS) immunoreactivity of the mouse hippocampal CA1 sector. NGF and BDNF immunoreactivity was unchanged in the hippocampal CA1 pyramidal neurons from 2 to 50-59 weeks of birth. In contrast, a significant increase in the NGF and BDNF immunoreactivity was observed in glial cells of the hippocampal CA1 sector from 40-42 to 50-59 weeks of birth. On the other hand, the number of parvalbumin- and nNOS-positive interneurons was unchanged in the hippocampal CA1 sector during aging processes, except for a significant decrease of nNOS-positive interneurons 2 weeks of birth. Our results indicate that NGF and BDNF immunoreactivity was unaltered in the hippocampal CA1 pyramidal neurons during aging processes. In contrast, a significant increase in the NGF and BDNF immunoreactivity was observed in glial cells of the hippocampal CA1 sector during aging processes. The present study also shows that the number of parvalbumin- and nNOS-positive interneurons was unchanged in the hippocampal CA1 sector during aging processes, except for a significant decrease of nNOS-positive interneurons 2 weeks of birth. These results demonstrate that the expression of glial NGF and BDNF may play a key role for helping survival and maintenance of pyramidal neurons and neuronal functions in the hippocampal CA1 sector during aging processes. Furthermore, our findings suggest that parvalbumin- and nNOS-positive interneurons in the hippocampal CA1 sector are resistant to aging processes. Moreover, our findings suggest that nitric oxide synthesized by the nNOS may play some role for neuronal growth during postnatal development.

Effective delivery of Pep-1-cargo protein into ischemic neurons and long-term neuroprotection of Pep-1-SOD1 against ischemic injury in the gerbil hippocampus

We examined the intracellular delivery of Pep-1-cargo protein against transient ischemic damage in the hippocampal CA1 region in gerbils. For this study, we introduced green fluorescent protein (GFP) and constructed Pep-1-GFP protein. At 12h after Pep-1-GFP treatment, GFP fluorescence was shown in almost CA1 pyramidal neurons in ischemic animals; in the sham-operated group, GFP fluorescence was shown in a few pyramidal neurons. Next, we confirmed the long-term effects of Pep-1-Cu,Zn-superoxide dismutase 1 (SOD1) against ischemic damage. In behavioral test, locomotor activity was significantly increased in Pep-1- and Pep-1-SOD1-treated groups 1 day after ischemia/reperfusion; the locomotor activity in the Pep-1-treated group was higher than that of the Pep-1-SOD1-treated group. Thereafter, the locomotor activity in both groups was decreased with time. Four days after ischemia/reperfusion, the locomotor activity in the Pep-1-SOD1-treated group was similar to that of the sham group; in the Pep-1-treated group, the activity was lower than that of the sham group. In the histochemical study, the cresyl violet positive neurons in the Pep-1-SOD1-treated group were abundantly detected in the hippocampal CA1 region 5 days after ischemia/reperfusion. In biochemical study, SOD1 protein level and activity in all Pep-1-treated ischemic groups were significantly lower than that of the Pep-1-SOD1-treated group. Our results indicate that Pep-1-cargo fusion proteins can be efficiently delivered into neurons in the ischemic hippocampus, and that Pep-1-SOD1 treatment in ischemic animals show a neuroprotection in the ischemic hippocampus for a long time.