Stress proteins as molecular markers of neurotoxicity

Psilocybin does not induce the vulnerability marker HSP70 in neurons susceptible to Olney's lesions

S-ketamine, a N-methyl-D-aspartate receptor (NMDAR) antagonist, and psilocybin, a 5-hydroxy-tryptamine (serotonin) 2A receptor (5-HT2AR) agonist, are reported as effective rapid-acting antidepressants. Both compounds increase glutamate signalling and evoke cortical hyperexcitation. S-ketamine induces neurotoxicity especially in the retrosplenial cortex (Olney's lesions). Whether psilocybin produces similar neurotoxic effects has so far not been investigated. We performed an immunohistochemical whole-brain mapping for heat shock protein 70 (HSP70) in rats treated with psilocybin, S-ketamine, and MK-801. In contrast to S-ketamine- and MK-801-treated animals, we did not detect any HSP70-positive neurons in retrosplenial cortex of rats treated with psilocybin. Our results suggest that psilocybin might be safer for clinical use compared to S-ketamine regarding neuronal damage.

Involvement of the heat shock response (HSR) regulatory pathway in cadmium-elicited cerebral damage

The heat shock response (HSR) is a cellular protective mechanism that is characterized by the induction of heat shock transcription factors (HSFs) and heat shock proteins (HSPs) in response to diverse cellular and environmental stressors, including cadmium (Cd). However, little is known about the relationship between the damaging effects of Cd and the HSR pathway in the chicken cerebrum following Cd exposure. To explore whether Cd exposure elicits cerebral damage and triggers the HSR pathway, chicks were exposed to Cd in the daily diet at different concentrations (35, 70, or 140 mg/kg feed) for 90 days, while a control group was fed the standard diet without Cd. Histopathological examination of cerebral tissue from Cd-exposed chickens showed neuronal damage, as evidenced by swelling and degeneration of neurons, loss of neurons, and capillary damage. Cd exposure significantly increased mRNA expression of HSF1, HSF2, and HSF3, and mRNA and protein expression of three major stress-inducible HSPs (HSP60, HSP70, and HSP90). Moreover, Cd exposure differentially modulated mRNA expression of small HSP (sHSPs), most notably reducing expression of HSP27 (HSPB1). Furthermore, Cd exposure increased TUNEL-positive neuronal apoptotic cells and up-regulated protein expression of caspase-1, caspase-8, caspase-3, and p53, leading to apoptosis. Taken together, these data demonstrate that activation of the HSR and apoptotic pathways by Cd exposure is involved in Cd-elicited cerebral damage in the chicken. Synopsis for the graphical abstract Cadmium (Cd)-induced neuronal damage triggers the heat shock response (HSR) by activating heat shock transcription factors (HSFs) and subsequent induction of major heat shock proteins (notably, HSP60, HSP70, and HSP90). Moreover, Cd exposure activates caspase-1, caspase-8, caspase-3, and p53 protein, thereby resulting in neuronal apoptosis in the chicken brain.

Downregulation of glob1 suppresses pathogenesis of human neuronal tauopathies in Drosophila by regulating tau phosphorylation and ROS generation

Human tauopathies represent a group of neurodegenerative disorders, characterized by abnormal hyperphosphorylation and aggregation of tau protein, which ultimately cause neurodegeneration. The aberrant tau hyperphosphorylation is mostly attributed to the kinases/phosphatases imbalance, which is majorly contributed by the generation of reactive oxygen species (ROS). Globin(s) represent a well-conserved group of proteins which are involved in O₂ management, regulation of cellular ROS in different cell types. Similarly, Drosophila globin1 (a homologue of human globin) with its known roles in oxygen management and development of nervous system exhibits striking similarities with the mammalian neuroglobin. Several recent evidences support the hypothesis that neuroglobins are associated with Alzheimer's disease pathogenesis. We herein noted that targeted expression of human-tau induces the cellular level of Glob1 protein in Drosophila tauopathy models. Subsequently, RNAi mediated restored level of Glob1 restricts the pathogenic effect of human-tau by minimizing its hyperphosphorylation via GSK-3β/p-Akt and p-JNK pathways. In addition, it also activates the Nrf2-keap1-ARE cascade to stabilize the tau-mediated increased level of ROS. These two parallel cellular events provide a significant rescue against human tau-mediated neurotoxicity in the fly models. For the first time we report a direct involvement of an oxygen sensing globin gene in tau etiology. In view of the fact that human genome encodes for the multiple Globin proteins including a nervous system specific neuroglobin; and therefore, our findings may pave the way to investigate if the conserved oxygen sensing globin gene(s) can be exploited in devising novel therapeutic strategies against tauopathies.

Diffuse Axonal Injury in the Rat Brain: Axonal Injury and Oligodendrocyte Activity Following Rotational Injury

Traumatic brain injury (TBI) commonly results in primary diffuse axonal injury (DAI) and associated secondary injuries that evolve through a cascade of pathological mechanisms. We aim at assessing how myelin and oligodendrocytes react to head angular-acceleration-induced TBI in a previously described model. This model induces axonal injuries visible by amyloid precursor protein (APP) expression, predominantly in the corpus callosum and its borders. Brain tissue from a total of 27 adult rats was collected at 24 h, 72 h and 7 d post-injury. Coronal sections were prepared for immunohistochemistry and RNAscope^® to investigate DAI and myelin changes (APP, MBP, Rip), oligodendrocyte lineage cell loss (Olig2), oligodendrocyte progenitor cells (OPCs) (NG2, PDGFRa) and neuronal stress (HSP70, ATF3). Oligodendrocytes and OPCs numbers (expressed as percentage of positive cells out of total number of cells) were measured in areas with high APP expression. Results showed non-statistically significant trends with a decrease in oligodendrocyte lineage cells and an increase in OPCs. Levels of myelination were mostly unaltered, although Rip expression differed significantly between sham and injured animals in the frontal brain. Neuronal stress markers were induced at the dorsal cortex and habenular nuclei. We conclude that rotational injury induces DAI and neuronal stress in specific areas. We noticed indications of oligodendrocyte death and regeneration without statistically significant changes at the timepoints measured, despite indications of axonal injuries and neuronal stress. This might suggest that oligodendrocytes are robust enough to withstand this kind of trauma, knowledge important for the understanding of thresholds for cell injury and post-traumatic recovery potential.

Histopatology and HSP70 analysis of the midgut of Rhinocricus padbergi (Diplopoda) in the evaluation of the toxicity of two new metallic-insecticides

Millipedes are organisms of the edaphic fauna and have been used as bioindicators for the evaluation of pollutants in the environment, as they are in constant contact with the soil. This study used the millipede Rhinocricus padbergi as surrogate to evaluate the toxicity of two metallic-insecticides that has been developed for leaf-cutting ants management. Millipedes were exposed in terrariums containing different concentrations of the metallic-insecticides and, after periods of 21 and 90 days, three individuals from each terrarium were dissected in order to remove the midgut, the organ where absorption of nutrients and, consequently, toxic substances occurs. The toxic action of the metallic-insecticides was analyzed through qualitative and semi-quantitative analysis of morphophysiological alterations and by quantitative analysis of the HSP70 stress protein. The results showed that the metallic-insecticides may increase HSP70 labeling, although not at all concentrations and periods of exposure. Histopathological alterations were not significant at any concentration, indicating that the cytoprotective action of HSP70 is able to prevent severe damage to the midgut. It is therefore suggested that the metallic-insecticides are not toxic to the species studied here as no toxicity was observed under the conditions tested. In addition, stress protein localization in midgut helps understand how morphophysiological processes can potentially be affected by pesticide exposure.

Induction of Oxidative Stress and Cell Death in Neural Cells by Silica Nanoparticles

Silica nanoparticles (SiNPs) are produced on an industrial scale and used in various fields including health care, because silica is stable, inexpensive, and easy to handle. Despite these benefits, there is concern that exposure to SiNPs may lead to adverse effects in certain types of cells or tissues, such as hemolysis, immune responses, and developmental abnormalities in the brain and developing embryos. Although investigations on the toxicity of SiNPs against neurons are essential for medicinal use, only a few studies have assessed the direct effects of SiNPs on cells derived from the central nervous system. In this study, we investigated the toxic effects of SiNPs on primary cultures of hippocampal cells, using SiNPs with diameters of 10-1500 nm. We showed that treatment with SiNPs caused oxidative stress and cell death. Furthermore, we found that these cytotoxicities were dependent on the particle size, concentration, and surface charge of SiNPs, as well as the treatment temperature. The toxicity was reduced by SiNP surface functionalization or protein coating and by pretreating cells with an antioxidant, suggesting that contact-induced oxidative stress may be partially responsible for SiNP-induced cell death. These data will be valuable for utilizing SiNPs in biomedical applications.

Protective Role of Hypothermia Against Heat Stress in Differentiated and Undifferentiated Human Neural Precursor Cells: A Differential Approach for the Treatment of Traumatic Brain Injury

Introduction:

The present study aimed to explore protective mechanisms of hypothermia against mild cold and heat stress on highly proliferative homogeneous human Neural Precursor Cells (NPCs) derived from Subventricular Zone (SVZ) of human fetal brain.

Methods:

CD133+ve enriched undifferentiated and differentiated human NPCs were exposed to heat stress at 42°C. Then, Western-blot quantification was performed using Hsp-70 (70 kilodalton heat shock proteins) recombinant protein. Finally, changes in pluripotency and Hsp-70 expression were measured using immunofluorescence staining and RT-qPCR (Quantitative reverse transcription PCR) analysis, respectively.

Results:

Heat stress resulted in abnormal neurospheres development. The apoptosis rate was enhanced during long-term in vitro culture of neurospheres. Neurogenic differentiation reduced and showed aberrent phenotypes during heat stress. After hypothermia treatment significant improvement in neurospheres and neuronal cell morphology was observed.

Conclusion:

Mild-hypothermia treatment induces attenuated heat shock response against heat stress resulting in induced HSP-70 expression that significantly improves structure and function of both undifferentiated human NPCs and differentiated neurons.

Remote effects of short-term neonatal hyperthermia in Krushinsky-Molodkina rats prone to audiogenic seizures strain

Using the audiogenic seizure prone Krushinsky-Molodkina rat strain, it was demonstrated that short-term (5 min) exposure of 14-day-old pups to an elevated temperature (42°C) resulted in a significant decrease in audiogenic seizure severity at the age of 1 month. Presumably, this effect is determined by the activation of the heat-shock protein system (stress proteins).

Knocking down of heat-shock protein 27 directs differentiation of functional glutamatergic neurons from placenta-derived multipotent cells

This study presents human placenta-derived multipotent cells (PDMCs) as a source from which functional glutamatergic neurons can be derived. We found that the small heat-shock protein 27 (HSP27) was downregulated during the neuronal differentiation process. The in vivo temporal and spatial profiles of HSP27 expression were determined and showed inverted distributions with neuronal proteins during mouse embryonic development. Overexpression of HSP27 in stem cells led to the arrest of neuronal differentiation; however, the knockdown of HSP27 yielded a substantially enhanced ability of PDMCs to differentiate into neurons. These neurons formed synaptic networks and showed positive staining for multiple neuronal markers. Additionally, cellular phenomena including the absence of apoptosis and rare proliferation in HSP27-silenced PDMCs, combined with molecular events such as cleaved caspase-3 and the loss of stemness with cleaved Nanog, indicated that HSP27 is located upstream of neuronal differentiation and constrains that process. Furthermore, the induced neurons showed increasing intracellular calcium concentrations upon glutamate treatment. These differentiated cells co-expressed the N-methyl-D-aspartate receptor, vesicular glutamate transporter, and synaptosomal-associated protein 25 but did not show expression of tyrosine hydroxylase, choline acetyltransferase or glutamate decarboxylase 67. Therefore, we concluded that HSP27-silenced PDMCs differentiated into neurons possessing the characteristics of functional glutamatergic neurons.

Impairment of translation in neurons as a putative causative factor for autism

BACKGROUND

A dramatic increase in the prevalence of autism and Autistic Spectrum Disorders (ASD) has been observed over the last two decades in USA, Europe and Asia. Given the accumulating data on the possible role of translation in the etiology of ASD, we analyzed potential effects of rare synonymous substitutions associated with ASD on mRNA stability, splicing enhancers and silencers, and codon usage.

PRESENTATION OF THE HYPOTHESIS

We hypothesize that subtle impairment of translation, resulting in dosage imbalance of neuron-specific proteins, contributes to the etiology of ASD synergistically with environmental neurotoxins.

TESTING THE HYPOTHESIS

A statistically significant shift from optimal to suboptimal codons caused by rare synonymous substitutions associated with ASD was detected whereas no effect on other analyzed characteristics of transcripts was identified. This result suggests that the impact of rare codons on the translation of genes involved in neuron development, even if slight in magnitude, could contribute to the pathogenesis of ASD in the presence of an aggressive chemical background. This hypothesis could be tested by further analysis of ASD-associated mutations, direct biochemical characterization of their effects, and assessment of in vivo effects on animal models.

IMPLICATIONS OF THE HYPOTHESIS

It seems likely that the synergistic action of environmental hazards with genetic variations that in themselves have limited or no deleterious effects but are potentiated by the environmental factors is a general principle that underlies the alarming increase in the ASD prevalence.

REVIEWERS

This article was reviewed by Andrey Rzhetsky, Neil R. Smalheiser, and Shamil R. Sunyaev.

Heat shock protein 70 protects against seizure-induced neuronal cell death in the hippocampus following experimental status epilepticus via inhibition of nuclear factor-κB activation-induced nitric oxide synthase II expression

Status epilepticus induces subcellular changes that may eventually lead to neuronal cell death in the hippocampus. Based on an animal model of status epilepticus, our laboratory showed previously that sustained hippocampal seizure activity activates nuclear factor-κB (NF-κB) and upregulates nitric oxide synthase (NOS) II gene expression, leading to apoptotic neuronal cell death in the hippocampus. The present study examined the potential modulatory role of heat shock protein 70 (HSP70) on NF-κB signaling in the hippocampus following experimental status epilepticus. In Sprague-Dawley rats, kainic acid (KA) was microinjected unilaterally into the hippocampal CA3 subfield to induce prolonged bilateral seizure activity. Expression of HSP70 was elevated as early as 1h after the elicitation of sustained seizure activity, followed by a progressive elevation that peaked at 24h. Pretreatment with an antisense oligonucleotide against hsp70 decreased the HSP70 expression, and significantly augmented IκB kinase (IKK) activity and phosphorylation of IκBα, alongside enhanced nuclear translocation and DNA binding activity of NF-κB in the hippocampal CA3 neurons and glial cells. These cellular events were followed by enhanced upregulation of NOS II and peroxynitrite expression 3h after sustained seizure activity that led to an increase of caspase-3 and DNA fragmentation in the hippocampal CA3 neurons 7days after experimental status epilepticus. We concluded that HSP70 protects against apoptotic cell death induced by NF-κB activation and NOS II-peroxynitrite signaling cascade in the hippocampal CA3 and glial cells following experimental status epilepticus via suppression of IKK activity and deactivation of IκBα.

Cytotoxicity and the induction of the stress protein Hsp 70 in Chang liver cells in response to zearalenone-induced oxidative stress

Zearalenone (ZEN) has been implicated in several cases of mycotoxicosis in farm animals and humans. The toxic effects of ZEN have been well characterized, but little is known regarding the mechanisms of ZEN toxicity, including the involvement of the oxidative stress pathway. Using Chang liver cells as a model, the aim of this study was to determine if ZEN could elevate the expression of the heat shock protein Hsp 70, induce cytotoxicity and modulate the levels of glutathione (GSH) and thiobarbituric acid reactive substance (TBARS). In addition, the cytoprotective effects of N-acetylcysteine amide (NACA) pre-treatment were assessed. Finally, the involvement of oxidative stress in ZEN-induced toxicity was confirmed. The results of this study demonstrated that ZEN-induced Hsp 70 expression in a dose- and time-dependent manners. This effect occurred at low-ZEN concentrations, and could therefore be considered a biomarker of ZEN-induced toxicity. The cytotoxicity was reduced when Chang liver cells were exposed to sub-lethal heat shock prior to ZEN treatment, demonstrating a cytoprotective effect of Hsp 70. This cytoprotective effect suggested that Hsp 70 might play a key role in the cellular defense mechanism. When cells were pre-treated with NACA prior to ZEN treatment, the cells were also protected from toxicity. This NACA cytoprotective effect suggested the involvement of oxidative stress in ZEN-induced toxicity, and this mechanism was supported by reduced Hsp 70 expression, inhibited cytolethality, increased GSH levels and decreased TBARS formation when cells were pre-treated with NACA prior to ZEN exposure. Our data clearly demonstrated that ZEN induced cytotoxicity in Chang liver cells by inhibiting cell proliferation, decreasing GSH levels and increasing TBARS formation in a dose-dependent manner. ZEN also, induced Hsp 70 expression, and the side effects of ZEN were significantly alleviated by pre-treatment with NACA. Oxidative stress is likely to be one of the primary pathways of ZEN toxicity. This oxidative stress may contribute, at least in part, to the mechanism of ZEN-induced cytotoxicity.

Astrogliosis and HSP 70 activation in neonate rats' brain exposed to sodium metavanadate through lactation

The effect of sodium metavanadate (NaVO3) exposure on lipid oxidative damage in the CNS of suckling rats was studied. Using histological markers of cellular injury, we also studied the morphological alterations of neurons and astroglial cells in different regions of neonate rats CNS after NaVO3 exposure. Dams of treated litters were intraperitoneally injected with 3mgNaVO3/kgbody weight/day during 12days starting on post-natal day (PND) 10. On the 21st PND, four pups of each litter were sacrificed by decapitation and six brain areas were removed for lipid peroxidation assay by the thiobarbituric acid (TBA) reaction, the other four were transcardially perfused-fixed and their brains were removed and cut with a cryostat. Brain sections were processed for: NADPHd histochemistry and anti-HSP70, anti-GFAP and anti-S100 immunohistochemistry. The relative optical density of the NADPHd stained layers and of S100 (+) astrocytes and the GFAP (+) astrocyte surface area in Cer and Hc were measured. Although MDA levels, S100 immunostaining and NADPHd activity didn't show differences between experimental and control groups, both astrogliosis and HSP70 activation were detected in Cer, while only the former was detected in Hc of V-exposed pups.

Cerebrospinal fluid protein biomarker panel for assessment of neurotoxicity induced by kainic acid in rats

Glutamate excitotoxicity plays a key role in the etiology of a variety of neurological, psychiatric, and neurodegenerative disorders. The goal of this study was to investigate spatiotemporal distribution in the brain and cerebrospinal fluid (CSF) concentrations of ubiquitin C-terminal hydrolase-1 (UCH-L1), glial fibrillary acidic protein (GFAP), αII-spectrin breakdown products (SBDP150, SBDP145, and SBDP120), and their relationship to neuropathology in an animal model of kainic acid (KA) excitotoxicity. Triple fluorescent labeling and Fluoro-Jade C staining revealed a reactive gliosis in brain and specific localization of degenerating neurons in hippocampus and entorhinal cortex of KA-treated rats. Immunohistochemistry showed upregulation of GFAP expression in hippocampus and cortex beginning 24h post KA injection and peaking at 48h. At these time points concurrent with extensive neurodegeneration all SBDPs were observed throughout the brain. At 24h post KA injection, a loss of structural integrity was observed in cellular distribution of UCH-L1 that correlated with an increase in immunopositive material in the extracellular matrix. CSF levels of UCH-L1, GFAP, and SBDPs were significantly increased in KA-treated animals compared with controls. The temporal increase in CSF biomarkers correlated with brain tissue distribution and neurodegeneration. This study provided evidence supporting the use of CSF levels of glial and neuronal protein biomarkers to assess neurotoxic damage in preclinical animal models that could prove potentially translational to the clinic. The molecular nature of these biomarkers can provide critical information on the underlying mechanisms of neurotoxicity that might facilitate the development of novel drugs and allow physicians to monitor drug safety.

Electromagnetic fields at 2.45 GHz trigger changes in heat shock proteins 90 and 70 without altering apoptotic activity in rat thyroid gland

Non-ionizing radiation at 2.45 GHz may modify the expression of genes that codify heat shock proteins (HSP) in the thyroid gland. Using the enzyme-linked immunosorbent assay (ELISA) technique, we studied levels of HSP-90 and HSP-70. We also used hematoxilin eosin to look for evidence of lesions in the gland and applied the DAPI technique of fluorescence to search for evidence of chromatin condensation and nuclear fragmentation in the thyroid cells of adult female Sprague-Dawley rats. Fifty-four rats were individually exposed for 30 min to 2.45 GHz radiation in a Gigahertz transverse electromagnetic (GTEM) cell at different levels of non-thermal specific absorption rate (SAR), which was calculated using the finite difference time domain (FDTD) technique. Ninety minutes after radiation, HSP-90 and HSP-70 had decreased significantly (P<0.01) after applying a SAR of 0.046±1.10 W/Kg or 0.104±5.10⁻³ W/Kg. Twenty-four hours after radiation, HSP-90 had partially recovered and HSP-70 had recovered completely. There were few indications of lesions in the glandular structure and signs of apoptosis were negative in all radiated animals. The results suggest that acute sub-thermal radiation at 2.45 GHz may alter levels of cellular stress in rat thyroid gland without initially altering their anti-apoptotic capacity.

Water extract from the leaves of Withania somnifera protect RA differentiated C6 and IMR-32 cells against glutamate-induced excitotoxicity

Glutamate neurotoxicity has been implicated in stroke, head trauma, multiple sclerosis and neurodegenerative disorders. Search for herbal remedies that may possibly act as therapeutic agents is an active area of research to combat these diseases. The present study was designed to investigate the neuroprotective role of Withania somnifera (Ashwagandha), also known as Indian ginseng, against glutamate induced toxicity in the retinoic acid differentiated rat glioma (C6) and human neuroblastoma (IMR-32) cells. The neuroprotective activity of the Ashwagandha leaves derived water extract (ASH-WEX) was evaluated. Cell viability and the expression of glial and neuronal cell differentiation markers was examined in glutamate challenged differentiated cells with and without the presence of ASH-WEX. We demonstrate that RA-differentiated C6 and IMR-32 cells, when exposed to glutamate, undergo loss of neural network and cell death that was accompanied by increase in the stress protein HSP70. ASH-WEX pre-treatment inhibited glutamate-induced cell death and was able to revert glutamate-induced changes in HSP70 to a large extent. Furthermore, the analysis on the neuronal plasticity marker NCAM (Neural cell adhesion molecule) and its polysialylated form, PSA-NCAM revealed that ASH-WEX has therapeutic potential for prevention of neurodegeneration associated with glutamate-induced excitotoxicty.

Kainic acid-induced changes in the opioid/nociceptin system and the stress/toxicity pathways in the rat hippocampus

Excitotoxicity is a contributing factor to the pathogenesis of acute or chronic neurodegenerative disease states. Kainic acid (KA) is an excitotoxic substance and the administration of it to rodents induces seizure activity (status epilepticus, SE) and leads to neurodegeneration. In this study the effect of KA-induced excitotoxicity on the G-protein activations and the gene expression levels of the opioid/nociceptin system receptors as MOPr, KOPr, DOPr, ORL-1, and PNOC (N/OFQ) were investigated, and the regulator effect of naloxone (Nal) on the gene expressions of the opioid system receptors against KA-induced seizures in the rat hippocampus was tested. In addition, the expression levels of stress-toxicity genes were assessed in the hippocampus following KA-induced excitotoxicity in order to determine the potential genetic targets which can be helpful for neuroprotective interventions. Our results indicate that the KA-induced excitotoxicity increased the mRNA levels of MOPr, DOPr, KOPr, PNOC, and ORL-1. However, G-protein activations of MOPr, DOPr, and KOPr remained relatively unchanged while both the potency and efficacy of N/OFQ were significantly increased. The PCR array data showed that KA-induced excitotoxicity altered the expression levels of genes in the cellular stress or toxicity pathways. Our data suggests that the induction of the opioid/nociceptin system may be involved in the cellular stress response following a neurodegenerative insult and that the genes modulated by the KA-treatment in the stress-toxicity pathways may be evaluated as targets of potential neuroprotective interventions.

Markers associated with testosterone enhancement of methamphetamine-induced striatal dopaminergic neurotoxicity

Intact male CD-1 mice received an injection of testosterone propionate (TP--5 ug), progesterone (P--5 mg), the oil vehicle or remained untreated (control). At 24 hours after hormonal treatments the mice received an injection of methamphetamine (MA--40 mg/kg) and rectal temperatures were measured. At 5 days post-MA, assays were performed to assess effects of these treatments. Maximal increases in body temperatures, that were significantly greater than oil-treated controls, were obtained in TP-treated mice. At 5 days post-MA, maximal weight reductions were obtained with TP-treated mice, while P-treated mice showed no significant decrease between the pre- versus post-MA determinations. Striatal dopamine concentrations showed maximal reductions and heat-shock protein-70 maximal increases in the TP group, with both differing significantly as compared with all other groups. Protein levels of dopamine transporters were significantly decreased in P-treated mice, while vesicular monoamine transporter-2 was significantly decreased in TP-treated mice. Taken together, these results suggest that testosterone exacerbates the deleterious effects of MA within male mice as indicated by a number of markers related to neurotoxicity. The changes in markers as associated with this enhanced neurotoxicity suggest that TP may increase thermal/energy responses and/or oxidative stress to produce this effect.

Neuroproteomics: a biochemical means to discriminate the extent and modality of brain injury

Diagnosis and treatment of stroke and traumatic brain injury remain significant health care challenges to society. Patient care stands to benefit from an improved understanding of the interactive biochemistry underlying neurotrauma pathobiology. In this study, we assessed the power of neuroproteomics to contrast biochemical responses following ischemic and traumatic brain injuries in the rat. A middle cerebral artery occlusion (MCAO) model was employed in groups of 30-min and 2-h focal neocortical ischemia with reperfusion. Neuroproteomes were assessed via tandem cation-anion exchange chromatography-gel electrophoresis, followed by reversed-phase liquid chromatography-tandem mass spectrometry. MCAO results were compared with those from a previous study of focal contusional brain injury employing the same methodology to characterize homologous neocortical tissues at 2 days post-injury. The 30-min MCAO neuroproteome depicted abridged energy production involving pentose phosphate, modulated synaptic function and plasticity, and increased chaperone activity and cell survival factors. The 2-h MCAO data indicated near complete loss of ATP production, synaptic dysfunction with degraded cytoarchitecture, more conservative chaperone activity, and additional cell survival factors than those seen in the 30-min MCAO model. The TBI group exhibited disrupted metabolism, but with retained malate shuttle functionality. Synaptic dysfunction and cytoarchitectural degradation resembled the 2-h MCAO group; however, chaperone and cell survival factors were more depressed following TBI. These results underscore the utility of neuroproteomics for characterizing interactive biochemistry for profiling and contrasting the molecular aspects underlying the pathobiological differences between types of brain injuries.

Vanadium (V)-Induced Neurotoxicity in the Rat Central Nervous System: A Histo-Immunohistochemical Study

As vanadium was found to induce oxidative stress in the central nervous system, the morphological alterations of neurons and astroglial cells in adult rat central nervous system after vanadium exposure was studied, using histological markers of cellular injury. Animals were intraperitoneally injected with 3 mg/kg body weight of sodium metavanadate for 5 consecutive days. NADPH diaphorase histochemistry and heat shock protein (hsp) 70, glial fibrillary acidic protein (GFAP), and S-100 immunohistochemistry were performed in floating sections of several brain areas. NADPHd staining was higher in the molecular and granular layers of the cerebellar cortex, and small NADPHd-stained interneurons were observed in hippocampal sections in V(+5)-exposed animals. hsp 70 immunostaining showed the presence of reactive neurons in cerebellum of treated animals. GFAP and S-100 immunohistochemistry showed enlarged astrocytes in cerebellum and hippocampus in the V(+5)-exposed animals. The histological markers used showed that the main areas affected by vanadium-mediated free-radical generation were the hippocampus and the cerebellum.

Toxicity and bioaccumulation of the wood preservative copper dimethyldithiocarbamate in tissues of Long-Evans rats

This study examined the toxicity and accumulation of copper in the livers and kidneys of Long-Evans rats after a subacute exposure to copper dimethyldithiocarbamate (CDCC) wood preservative. CDDC was recently introduced as an alternative to chromated copper arsenate (CCA) preserved wood. Female rats (220-270 g) were treated with 0, 25, 50, or 75 mg/kg CDDC by oral gavage for 3 wk. Light microscopy revealed that higher doses of CDDC induced diffuse necrosis and a loss of sinusoids in the livers of Long-Evans rats with vacuolization in the highest dose. Rats treated with 25 mg/kg CDDC displayed a thickening of the basement membrane of Bowman's capsule and the mesangium. Exposure to higher CDDC concentrations (50 and 75 mg/kg) showed moderate to marked expansion of the mesangial matrix and glomerular necrosis with an overall loss of glomerular structure seen in the highest dose. The concentration of copper was significantly increased in the tissues of animals exposed to CDDC in a dose-dependent manner. Western blot analysis revealed the induction of the stress protein Hsp70 and the formation of 4-hydroxy-2-nonenal (4HNE) adducts in liver and renal tissues, indicating peroxidative damage. CDDC was shown to be toxic to the livers and kidneys, at all doses used, and this toxicity is related to peroxidative insult.

Heat-shock protein-70 genes and response to antidepressants in major depression

In the search of predictors of antidepressant efficacy, much interest has recently focused on pro-inflammatory proteins, as they were found to be elevated during major depressives states and decreased by antidepressant drugs. In the present paper we investigated the role of the genes coding for heat-shock-70 family proteins, recently hypothesized to be activated by antidepressants and thus mediate the reduction of pro-inflammatory cytosines. One hundred and forty two hospitalised patients, affected by major depression and treated with antidepressants drugs for a major depressive episode were evaluated for depressive severity at the baseline and at the discharge and genotyped for five SNPs within the genes HSPA1L, HSPA1A and HSPA1B. Markers were not individually associated with symptom severity after treatment. Instead, we found a three markers haplotype, including SNPs within HSPA1L and HSPA1A, associated with a poorer response to antidepressant treatment (p=0.005). Single markers as well as haplotypes were not associated with other clinical features. In conclusion, genetic variants within the genes coding for HSP-70 family proteins may affect the action of antidepressants and thus their therapeutic efficacy.

Induction of Hsp 70 in Vero cells in response to mycotoxins

This paper analysed the toxicity mechanisms of several mycotoxins using Hsp 70 expression, cytoprotection of Vero cells by sub-lethal heat shock (sub-LHS) and Vitamin E. Our aim was (i) to determine whether Citrinin (CTN), Zearalenone (ZEN) and T2 toxin (T2) could induce the expression of Hsp 70, (ii) to check whether or not elevated levels of Hsp and Vitamin E pre-treatment could provide cytoprotection from these mycotoxins, and finally (iii) to emphasize the eventual involvement of oxidative stress on mycotoxin's toxicity. Our study demonstrated that the three examined mycotoxins induced Hsp 70 expression in a dose-dependent manner. A cytoprotective effect of Hsp 70 was obtained when Vero cells were exposed to sub-lethal heat shock followed by a 12h recovery prior to mycotoxins treatment and evidenced by a reduction of their cytolethality. This cytoprotection suggested that Hsp 70 might constitute an important cellular defence mechanism. A cytoprotective action was also obtained although at lesser extent, when cells were pre-treated with an antioxidant agent, the Vitamin E before mycotoxins treatment. This Vitamin E cytoprotection evoked the involvement of oxidative stress in mycotoxins induced toxicity, which was further, confirmed by the reduction of Hsp 70 expression when cells were pre-treated with Vitamin E prior to mycotoxins. Our data clearly shows that oxidative stress is certainly involved in the toxicity of the three studied mycotoxins, Citrinin, Zearalenone and T2 toxin and may therefore constitutes a relevant part in their toxicities; however, at variable extent from one mycotoxin to another.

Blood content modulates the induction of heat shock proteins in the neurovascular network

Heat shock proteins are ubiquitous members of a family of molecular chaperones that protect various cell populations from injury. Up-regulation of heat shock proteins, particularly the 70 kDa species, bind selectively to denatured or partially damaged polypeptides that would otherwise perturb cell function and initiate cell death programs. In this regard, induction of heat shock proteins provides protection from cerebral ischemia in animal models of stroke. Endothelial cells, in particular, are intimately involved in the above protective event as these cells mount a stress response with induction of the 70 kDa heat shock protein. However, the coupling of heat shock proteins and the neurovascular response are not yet known. Here we show that blood content is an important factor in this stress response as rats devoid of blood content do not display a heat shock response in the microvasculature of the hippocampal formation. This lack of stress response, however, is reversed when rats are reperfused with exogenous rat or human blood content. We propose a new ischemic-sensing role for blood that serves to integrate information about protein-damaging conditions and heat shock protein levels in the neurovascular network. Further characterization of this sensing role could represent an attractive new approach to treatment of global ischemia and other microvascular pathologies.

Protective role of heat shock and heat shock protein 70 in lactacystin-induced cell death both in the rat substantia nigra and PC12 cells

Proteasomal dysfunction plays an important role in the pathogenesis of Parkinson disease (PD). Although clinical and experimental evidence continues to accumulate indicating heat shock protein 70 (HSP70) is significant in the pathogenesis of PD, few studies have been made to investigate the role of HSP70 under the condition of proteasome dysfunction. In in vivo study, we infused lactacystin into the unilateral substantia nigra (SN) of Sprague-Dawley rats with or without preceding whole body hyperthermia (WBH). Immunohistochemical studies showed the death of dopaminergic neurons and activated microglia in the SN. Lactacystin with prior WBH increased the expression of HSP70 more than did lactacystin alone and decreased lactacystin-induced dopaminergic neuronal death in the SN. In PC12 cells, heat shock pretreatment decreased lactacystin-induced cell death. Although additional treatment of nocodazole, ammonium chloride, and 3-methyladenine augmented cell death by lactacystin, heat shock pretreated to these drugs offsets their additional toxicity. These results indicate that heat shock proteins, especially HSP70, could play an important role under the condition of proteasome dysfunction in part by fostering aggresome formation and lysosome-mediated autophagy.

Protective effect of vineatrol against kainic acid induced seizures, oxidative stress and on the expression of heat shock proteins in rats

The aim of the present study was to evaluate the effect of an antioxidant vineatrol against kainic acid-induced seizures, markers of oxidative stress and expression of heat shock protein in brain. In rats, kainic acid (10 mg/kg i.p.) induced long lasting seizures, associated behavioral symptoms and brain damage and significantly increased level of brain malondialdehyde (MDA) (283 +/- 42 nmol/g wet tissue) as compared to control (173.3 +/- 10.2 nmol/g wet tissue). Pretreatment (5 min) of vineatrol (10, 20 and 40 mg/kg i.p.) could not inhibit the convulsions though the latency was significantly increased with 20 and 40 mg/kg. However when the drug was administrated 5 min prior and repeated at 30 and 90 min after kainic acid there was significant reduction in incidence of convulsions. The brain MDA levels were also found to be significantly attenuated, however the glutathione levels were not different in control, kainic acid and vineatrol treated animals. Expression of heat shock protein (HSP) 72 was observed in the kainic acid per se group indicating neurotoxicity as compared to the control group and was reduced by vineatrol. The study suggests the potential use of vineatrol in status epilepticus.

Hsp70 accumulation and ultrastructural features of lung and liver induced by ethanol treatment with and without l-carnitine protection in rats

This study examined Hsp70 accumulation and the subcellular characteristics of liver and lung when exposed to ethanol (EtOH), with and without L-carnitine protection. Female Sprague-Dawley rats, 150-200 g body weight, were randomized into four groups: Control (CON), Alcohol (ALC), L-carnitine (CAR) and Alcohol-L-carnitine (ALC-CAR). EtOH was administered per os at a dose of 4 g/kg body weight (1 ml) daily for 4 weeks. Before alcohol intake, an oral dose of 500 mg/kg body weight of L-carnitine was also administered to the ALC-CAR group. The liver and lung samples were subjected to Hsp70 Western blot and ultrastructural analysis. The Hsp70 accumulation was higher in the liver than in the lung samples. Hepatic Hsp70 accumulation was similar for all groups in contrast to lung, where the Hsp70 accumulation depends on the group studied. The ultrastructural results showed lung but not liver alterations, evidencing a stressful condition and subsequent cellular injury for lung tissue but not for liver. The ALC-CAR group showed less lung damage than the non-protected group and resembles the general appearance of the CON and CAR groups. EtOH intoxication induced differential cellular response in liver and lung in a dose and tissue dependent manner. L-carnitine seems to reduce lung EtOH-induced subcellular damage. The promotion of heat shock or stress proteins might represent one of the mechanisms involved that need to be further investigated.

Administration of Hsp70 in vivo inhibits motor and sensory neuron degeneration

The induction of heat shock proteins (Hsps) serves not only as a marker for cellular stress but also as a promoter of cell survival, which is especially important in the nervous system. We examined the regulation of the constitutive and stress-induced 70-kD Hsps (Hsc70 and Hsp70, respectively) after sciatic nerve (SN) axotomy in the neonatal mouse. Additionally, the prevention of axotomy-induced SN cell death by administration of several preparations of exogenous Hsc70 and Hsp70 was tested. Immunohistochemistry and Western blot analyses showed that endogenous levels of Hsc70 and Hsp70 did not increase significantly in lumbar motor neurons or dorsal root ganglion sensory neurons up to 24 hours after axotomy. When a variety of Hsc70 and Hsp70 preparations at doses ranging from 5 to 75 microg were applied to the SN stump after axotomy, the survival of both motor and sensory neurons was significantly improved. Thus, it appears that motor and sensory neurons in the neonatal mouse do not initiate a typical Hsp70 response after traumatic injury and that administration of exogenous Hsc/Hsp70 can remedy that deficit and reduce the subsequent loss of neurons by apoptosis.

Correlation of lymphocyte heat shock protein 70 levels with neurologic deficits in elderly patients with cerebral infarction

PURPOSE

To assess the association between heat shock protein 70 (HSP70) levels and the severity of ischemic stroke in elderly patients.

METHODS

We conducted a case-control study to investigate the changes in lymphocyte HSP70 levels by immunoblot in 65 elderly patients with mild (n = 22), intermediate (n = 21), or severe (n = 22) stroke, and in 34 healthy controls. We analyzed correlations between HSP70 levels and neurologic deficit scores on days 1, 15, and 30 after the onset of stroke.

RESULTS

Mean (+/- SD) HSP70 levels were higher in all stroke patients compared with controls (mild stroke: 709 +/- 194 units; intermediate: 585 +/- 165 units; severe: 421 +/- 124 units; controls: 86 +/- 34 units on day 1). Patients with mild stroke had higher levels at day 1 and 15 than did patients with severe stroke. HSP70 levels decreased rapidly from days 1 to 30 in all patients, except in patients with severe stroke, in whom levels decreased slowly between days 15 and 30. There were significant negative correlations between HSP70 levels and neurologic deficit scores in patients on days 1 (r = -0.53, P < 0.001) and 15 (r = -0.54, P < 0.001), but a positive correlation on day 30 (r = 0.49, P < 0.001).

CONCLUSION

These data suggest that HSP70 may be a marker for neuroprotection in the early stage of ischemic stroke and a marker for a crisis in the later stages of severe cerebral infarction. Further studies on the use of lymphocyte HSP70 levels in predicting clinical outcomes and underlying mechanisms in cerebral infarction are warranted.

Protective effect of vitamin C against the ethanol mediated toxic effects on human brain glial cells

It is now known that chronic consumption of excessive amounts of alcohol is a major source of social and medical problems. Ethanol-mediated glial cell activation may lead to neuron damage in many ways, including the formation of free radicals and production of pro-inflammatory molecules. Vitamin C (vit-C) is an essential dietary nutrient required as a co-factor for many enzymes and a very efficient antioxidant, protecting cells against free radical-mediated damage. The objective of this study was to evaluate the protective effects of vit-C on glial cell activation and viability against ethanol-mediated toxicity. Human brain astrocyte cells (HA) were exposed to ethanol (0, 50, and 350 mmol/L) for 24 h. We found that glial cells incubated with different concentrations of vit-C increase their vit-C in a dose-dependent manner. HA incubated with 0, 50 or 350 mmol/L of ethanol for up to 24 h showed toxic effects that were proportional to the levels of ethanol in the medium, HA showed increased levels of heat shock protein (Hsp70). However, cells enriched with vit-C before being exposed to ethanol, were better protected against the alcohol-mediated toxicity than non-supplemented cells, and showed significantly lower concentrations of Hsp70. Ethanol also caused increased expression of cyclooxygenase-2 (COX-2) and synthesis of prostaglandin E2 (PGE2), which were reduced by vit-C. In summary, HA supplemented with vit-C were significantly more resistant to the ethanol-mediated toxic effects.

Sudden and unexpected death in epilepsy (SUDEP): evidence of acute neuronal injury using HSP-70 and c-Jun immunohistochemistry

Post-mortem and neuropathological examination in sudden and unexpected death in epilepsy (SUDEP) shows no specific lesions and the exact cause and mechanism of death in these cases remains undetermined. There is clinical evidence to support the fact that SUDEP is a seizure-mediated event, and patients with poorly controlled seizures are at higher risk. We aimed to identify any evidence of acute neuronal injury in SUDEP cases at post-mortem to support that a recent seizure had occurred. We analysed the distribution and frequency of heat shock protein (HSP)-70 and c-Jun immunopositive neurones in the hippocampus in 18 SUDEP cases and 22 control cases, both markers being nonspecific but early and reliable indicators of acute neuronal injury. Post-mortem control groups included patients with epilepsy with cause of death other than SUDEP (including status epilepticus and accidental death), and patients with sudden cardiac death without an epilepsy history. An additional surgical control group included patients with refractory epilepsy and hippocampal sclerosis who had undergone temporal lobectomy. Semiquantitative analysis of the distribution of HSP-70 staining showed significantly more SUDEP cases with positively labelled neurones in hippocampal subfields compared to epilepsy and cardiac post-mortem controls (P < 0.001) but not compared to the epilepsy surgical controls (P = 0.4). No significant difference in immunostaining patterns between groups was seen in the parahippocampal gyrus with HSP-70 or with c-Jun in either the hippocampus or parahippocampal gyrus regions. The detection of HSP-70 positive neurones in the hippocampus in SUDEP is supportive of ante-mortem neuronal injury including a recent seizure prior to death.

Differential heat shock gene hsp70-1 response to toxicants revealed by in vivo study of lungs in transgenic mice

Members of heat shock proteins (Hsp70) family have been considered to respond to a large variety of stressful conditions. But it was suggested that, in pulmonary cells, Hsp response depends more closely on the type of stimulus. The lungs are critical organs potentially subjected to air pollution affecting respiratory function and, therefore, these organs are of particular interest with regard to the stress response. To investigate the stress dependence of Hsp70 response in lungs, we created transgenic mice where the firefly luciferase reporter gene is under the control of the murine hsp70-1 promoter and exposed them to different sublethal toxic conditions. For each condition, the level of transgene induction and pulmonary toxicity were assessed. We found that hsp70-1 promoter was stimulated by heat shock and cadmium but not by ozone, paraquat, and parathion, even if these chemicals induced respiratory distress and lung inflammation. Similar observations were made when expression of the endogenous hsp70-1 gene was analyzed, indicating that our transgenic model was accurately detecting hsp70-1 induction. Thereby, it appeared that hsp70-1 response is selective and depends on signaling pathways triggered by the toxicants rather than by their pathologic toxicity per se. Furthermore, because all the chemicals used in our study have been previously described to increase the level of oxidative stress, it indicates that there is no direct and simple correlation between hsp70-1 response and the level of oxidative stress, but more specific oxidative patterns should be involved in Hsp regulation.

Differential expression of molecular chaperones in brain of patients with Down syndrome

Heat shock proteins (HSPs) in their molecular capacity as chaperones have been reported to regulate the apoptotic pathway and also play a critical role in protein conformational diseases such as Alzheimer's disease (AD). As all Down syndrome (DS) brains display AD-like neuropathology, neuronal loss in DS was shown to be mediated by apoptosis. We decided to investigate the expression patterns of HSPs in seven brain regions of adults with DS using two-dimensional polyacrylamide gel electrophoresis (2-DE). Following 2-DE, approximately 120 protein spots were successfully identified by matrix-assisted laser desorption/ionization--mass spectrometry (MALDI-MS) followed by quantification of the identified proteins. We unambiguously identified and quantified nine different chaperone proteins. Accordingly, all but three chaperone proteins did exhibit a significant change in expression. HSP 70 RY, heat shock cognate (HSC) 71 and glucose-regulated protein (GRP) 75 showed a significant decrease (P < 0.05) in DS temporal cortex whereas HSP 70.1 and GRP 78 were significantly increased (P<0.05) in cerebellum. Whilst T-complex 1 (TCP-1) epsilon subunit showed a significant decrease (P< 0.05) in parietal cortex, a similar extent of increase (P<0.05) as that observed in cerebellum was obtained in parietal levels of GRP 78. Alpha-crystallin B, HSP 60 and GRP 94 did not show any detectable changes in expression patterns. This report presents the first approach to quantify nine different chaperones simultaneously at the protein level in different brain regions and provides evidence for aberrant chaperone expression patterns in DS. The relevance of this aberrant expression patterns are discussed in relation to the biochemical and neuropathological abnormalities in DS brain.

A gene expression profile of Alzheimer's disease

Postmortem analysis of brains of patients with Alzheimer's disease (AD) has led to diverse theories about the causes of the pathology, suggesting that this complex disease involves multiple physiological changes. In an effort to better understand the variety and integration of these changes, we generated a gene expression profile for AD brain. Comparing affected and unaffected brain regions in nine controls and six AD cases, we showed that 118 of the 7050 sequences on a broadly representative cDNA microarray were differentially expressed in the amygdala and cingulate cortex, two regions affected early in the disease. The identity of these genes suggests the most prominent upregulated physiological correlates of pathology involve chronic inflammation, cell adhesion, cell proliferation, and protein synthesis (31 upregulated genes). Conversely, downregulated correlates of pathology involve signal transduction, energy metabolism, stress response, synaptic vesicle synthesis and function, calcium binding, and cytoskeleton (87 downregulated genes). The results support several separate theories of the causes of AD pathology, as well as add to the list of genes associated with AD. In addition, approximately 10 genes of unknown function were found to correlate with the pathology.

Minimal ischaemic neuronal damage and HSP70 expression in MF1 strain mice following bilateral common carotid artery occlusion

Investigation into the influence of specific genes and gene products upon the pathophysiology of cerebral ischaemia has been greatly enhanced by the use of genetically modified mice. A simple model of global cerebral ischaemia in mouse is bilateral common carotid artery occlusion (BCCAo) and the neuropathological impact of BCCAo has been investigated in several mouse strains. Bilateral carotid occlusion produces extensive neuronal damage in C57Bl/6J strain mice and this damage is linked to posterior communicating artery (PcomA) hypoplasticity in the circle of Willis. In the present study, we investigated the effect of BCCAo in MF1 strain mice and compared them with C57Bl/6J mice. The neuropathological consequences of BCCAo were assessed using standard histochemical staining and heat shock protein 70 (HSP70) immunohistochemical staining (to demarcate cells that had been ischaemically stressed). The effect of BCCAo on mean arterial blood pressure (MABP) was also measured. The plasticity of the circle of Willis was recorded using carbon black perfusion. MF1 mice displayed significantly less ischaemic neuronal damage and HSP70 immunoreactivity compared to C57Bl/6J mice following 10-20 min BCCAo. Moreover, ischaemic neuronal damage and HSP70 immunoreactivity in MF1 mice subjected to extended BCCAo (25-45 min) was never as extensive or widespread as that observed in C57Bl/6J mice after 20 min BCCAo. MABP in MF1 mice (102+/-5 mmHg) was significantly higher than in C57Bl/6J mice (87+/-5) during 20 min BCCAo. MABP in MF1 mice during 20 and 40 min (103+/-12 mmHg) BCCAo remained above pre-occlusion values for the entire occlusion period. MF1 mice had significantly greater circle of Willis plasticity (more PcomAs) than C57Bl/6J mice did. These data indicate that MF1 mice are less susceptible to BCCAo than C57Bl/6J mice and that this could be due to maintained increases in MABP during BCCAo and the lower prevalence of abnormalities of the circle of Willis in MF1 mice.

Deranged expression of molecular chaperones in brains of patients with Alzheimer's disease

Alzheimer's disease (AD) is one of the disorders caused by protein conformational changes and recent studies have shown that several chaperone proteins are involved in this process. As information of chaperone expression in AD brain is limited, we aimed to study the expressional pattern of chaperones in several brain regions, as this may be essential to understand how folding defects can lead to disease. We studied the concomitant expressional patterns of molecular chaperones in seven brain regions of adults with AD using two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-associated laser desorption ionization mass spectroscopy (MALDI-MS). We unambiguously identified and quantified nine different chaperone proteins. Six chaperone proteins, heat shock protein 60 (HSP 60), HSP 70 RY, heat shock cognate (HSC) 71, alpha crystallin B chain, glucose regulated protein (GRP) 75, and GRP 94 showed aberrant expressional patterns depending on brain region. HSP 70.1, GRP 78 and T-complex 1 (TCP-1) epsilon subunit did not show any significant expressional change. These findings are compatible with neuropathological and biochemical abnormalities in AD brain and this report presents the first approach to quantify nine different chaperones simultaneously at the protein level in individual AD brain regions providing evidence for the relevance of aberrant chaperone expression to AD neuropathology.