Prevention of tau seeding and propagation by immunotherapy with a central tau epitope antibody.

Tauopathies are neurodegenerative diseases characterized by the intraneuronal accumulation of aggregated tau. The staging of this neurodegenerative process is well established for Alzheimer's disease as well as for other tauopathies. The stereotypical pattern of tau pathology in these diseases is consistent with the hypothesis that the tau protein can spread in a 'prion-like' manner. It proposes that extracellular pathological tau species can transmit pathology from cell to cell. Accordingly, by targeting these spreading species with therapeutic antibodies one should be able to slow or halt the progression of tau pathology. To be effective, antibodies should neutralize the pathological species present in Alzheimer's disease brains and block their cell-to-cell spread. To evaluate both aspects, tau antibody D, which recognizes an epitope in the central region of tau, and was selected for its outstanding ability to block tau seeding in cell based assays, was used in this study. Here, we addressed two fundamental questions: (i) can this anti-tau antibody neutralize the pathological species present in Alzheimer's disease brains; and (ii) can it block the cell-to-cell spread of tau seeds in vivo? First, antibody D effectively prevented the induction of tau pathology in the brains of transgenic mice that had been injected with human Alzheimer's disease brain extracts, showing that it could effectively neutralize the pathological species present in these extracts. Second, by using K18 P301L tau fibrils to induce pathology, we further demonstrated that antibody D was also capable of blocking the progression of tau pathology to distal brain regions. In contrast, an amino-terminal tau antibody, which was less effective at blocking tau seeding in vitro showed less efficacy in reducing Alzheimer's disease patient tau driven pathology in the transgenic mouse model. We did not address whether the same is true for a spectrum of other amino-terminal antibodies that were tested in vitro. These data highlight important differences between tau antibodies and, when taken together with other recently published data, suggest that epitope may be important for function.

Development of a Rat Model for Glioma-Related Epilepsy.

Seizures are common in patients with high-grade gliomas (30-60%) and approximately 15-30% of glioblastoma (GB) patients develop drug-resistant epilepsy. Reliable animal models are needed to develop adequate treatments for glioma-related epilepsy. Therefore, fifteen rats were inoculated with F98 GB cells (GB group) and four rats with vehicle only (control group) in the right entorhinal cortex. MRI was performed to visualize tumor presence. A subset of seven GB and two control rats were implanted with recording electrodes to determine the occurrence of epileptic seizures with video-EEG recording over multiple days. In a subset of rats, tumor size and expression of tumor markers were investigated with histology or mRNA in situ hybridization. Tumors were visible on MRI six days post-inoculation. Time-dependent changes in tumor morphology and size were visible on MRI. Epileptic seizures were detected in all GB rats monitored with video-EEG. Twenty-one days after inoculation, rats were euthanized based on signs of discomfort and pain. This study describes, for the first time, reproducible tumor growth and spontaneous seizures upon inoculation of F98 cells in the rat entorhinal cortex. The development of this new model of GB-related epilepsy may be valuable to design new therapies against tumor growth and associated epileptic seizures.

Anticonvulsant and antiepileptogenic effects of system xc- inactivation in chronic epilepsy models.

OBJECTIVE: The cystine/glutamate antiporter system xc- could represent a new target for antiepileptogenic treatments due to its crucial roles in glutamate homeostasis and neuroinflammation. To demonstrate this, we compared epilepsy development and seizure susceptibility in xCT knockout mice (xCT-/- ) and in littermate controls (xCT+/+ ) in different chronic models of epilepsy. METHODS: Mice were surgically implanted with electrodes in the basolateral amygdala and chronically stimulated to develop self-sustained status epilepticus (SSSE); continuous video-electroencephalography monitoring was performed for 28 days after SE and hippocampal histopathology was assessed. Corneal kindling was induced by twice daily electrical stimulation at 6 Hz and maintenance of the fully kindled state was evaluated. Next, messenger RNA (mRNA) and protein levels of xCT and of the proteins involved in the phosphoinositide 3-kinase (PI3K)/Akt/glycogen synthase kinase 3ß (GSK-3ß)/eukaryotic initiation factor 2α (eIF2α)/activating transcription factor 4 (ATF4) signaling pathway were measured at different time points during epileptogenesis in NMRI mice treated with pilocarpine. Finally, the anticonvulsant effect of sulfasalazine (SAS), a nonselective system xc- inhibitor, was assessed against 6 Hz-evoked seizures in pilocarpine-treated mice. RESULTS: In the SSSE model, xCT-/- mice displayed a significant delayed epileptogenesis, a reduced number of spontaneous recurrent seizures, and less pronounced astrocytic and microglial activation. Moreover, xCT-/- mice showed reduced seizure severity during 6 Hz kindling development and a lower incidence of generalized seizures during the maintenance of the fully kindled state. In pilocarpine-treated mice, protein levels of the PI3K/Akt/GSK-3ß/eIF2α/ATF4 pathway were increased during the chronic phase of the model, consistent with previous findings in the hippocampus of patients with epilepsy. Finally, repeated administration of SAS protected pilocarpine-treated mice against acute 6 Hz seizure induction, in contrast to sham controls, in which system xc- is not activated. SIGNIFICANCE: Inhibition of system xc- could be an attractive target for the development of new therapies with a potential for disease modification in epilepsy.

Epitope determines efficacy of therapeutic anti-Tau antibodies in a functional assay with human Alzheimer Tau.

In Alzheimer's disease (AD) and other tauopathies, the cytosolic protein Tau misfolds and forms intracellular aggregates which accumulate within the brain leading to neurodegeneration. Clinical progression is tightly linked to the progressive spread of Tau pathology throughout the brain, and several lines of evidence suggest that Tau aggregates or "seeds" may propagate pathology by spreading from cell to cell in a "prion like" manner. Accordingly, blocking the spread of extracellular seeds with an antibody could be a viable therapeutic approach. However, as the structure of Tau seeds is unknown, it is only possible to rationally design therapeutic Tau antibodies by making a priori assumptions. To avoid this, we developed a robust and quantitative cell based assay and employed an unbiased screening approach to identify the antibody with the highest activity against human Tau seeds. The selected antibody (D), directed to the mid-region of Tau (amino acids 235-250), potently blocked the seeding of human AD Tau and was also fully efficacious against seeds from progressive supranuclear palsy. When we compared this antibody with previously described reference antibodies, we were surprised to find that none of these antibodies showed comparable efficacy against human pathological seeds. Our data highlight the difficulty of predicting antibody accessible epitopes on pathological Tau seeds and question the potential efficacy of some of the Tau antibodies that are currently in clinical development.

The tau positron-emission tomography tracer AV-1451 binds with similar affinities to tau fibrils and monoamine oxidases.

BACKGROUND: Lilly/Avid's AV-1451 is one of the most advanced tau PET tracers in the clinic. Although results obtained in Alzheimer's disease patients are compelling, discrimination of tracer uptake in healthy individuals and patients with supranuclear palsy (PSP) is less clear as there is substantial overlap of signal in multiple brain regions. Moreover, accurate quantification of [18 F]AV-1451 uptake in Alzheimer's disease may not be possible. OBJECTIVES: The aim of the present study was to characterize the in vitro binding of AV-1451 to understand and identify potential off-target binding that could explain the poor discrimination observed in PSP patients. METHODS: [3 H]AV-1451 and AV-1451 were characterized in in vitro binding assays using recombinant and native proteins/tissues from postmortem samples of controls and Alzheimer's disease and PSP patients. RESULTS: [3 H]AV-1451 binds to multiple sites with nanomolar affinities in brain homogenates and to tau fibrils isolated from Alzheimer's disease or PSP patients. [3 H]AV-1451 also binds with similarly high affinities in brain homogenates devoid of tau pathology. This unexpected binding was demonstrated to be because of nanomolar affinities of [3 H]AV-1451 for monoamine oxidase A and B enzymes. CONCLUSIONS: High affinity of AV-1451 for monoamine oxidase proteins may limit its utility as a tau PET tracer in PSP and Alzheimer's disease because of high levels of monoamine oxidase expression in brain regions also affected by tau deposition, especially if monoamine oxidase levels change over time or with a treatment intervention. © 2017 International Parkinson and Movement Disorder Society.

p57(KIP2) regulates radial glia and intermediate precursor cell cycle dynamics and lower layer neurogenesis in developing cerebral cortex.

During cerebral cortex development, precise control of precursor cell cycle length and cell cycle exit is required for balanced precursor pool expansion and layer-specific neurogenesis. Here, we defined the roles of cyclin-dependent kinase inhibitor (CKI) p57(KIP2), an important regulator of G1 phase, using deletion mutant mice. Mutant mice displayed macroencephaly associated with cortical hyperplasia during late embryogenesis and postnatal development. Embryonically, proliferation of radial glial cells (RGC) and intermediate precursors (IPC) was increased, expanding both populations, with greater effect on IPCs. Furthermore, cell cycle re-entry was increased during early corticogenesis, whereas cell cycle exit was augmented at middle stage. Consequently, neurogenesis was reduced early, whereas it was enhanced during later development. In agreement, the timetable of early neurogenesis, indicated by birthdating analysis, was delayed. Cell cycle dynamics analyses in mutants indicated that p57(KIP2) regulates cell cycle length in both RGCs and IPCs. By contrast, related CKI p27(KIP1) controlled IPC proliferation exclusively. Furthermore, p57(KIP2) deficiency markedly increased RGC and IPC divisions at E14.5, whereas p27(KIP1) increased IPC proliferation at E16.5. Consequently, loss of p57(KIP2) increased primarily layer 5-6 neuron production, whereas loss of p27(KIP1) increased neurons specifically in layers 2-5. In conclusion, our observations suggest that p57(KIP2) and p27(KIP1) control neuronal output for distinct cortical layers by regulating different stages of precursor proliferation, and support a model in which IPCs contribute to both lower and upper layer neuron generation.

ΔFosB is part of a homeostatic mechanism that protects the epileptic brain from further deterioration.

Activity induced transcription factor ΔFosB plays a key role in different CNS disorders including epilepsy, Alzheimer's disease, and addiction. Recent findings suggest that ΔFosB drives cognitive deficits in epilepsy and together with the emergence of small molecule inhibitors of ΔFosB activity makes it an interesting therapeutic target. However, whether ΔFosB contributes to pathophysiology or provides protection in drug-resistant epilepsy is still unclear. In this study, ΔFosB was specifically downregulated by delivering AAV-shRNA into the hippocampus of chronically epileptic mice using the drug-resistant pilocarpine model of mesial temporal epilepsy (mTLE). Immunohistochemistry analyses showed that prolonged downregulation of ΔFosB led to exacerbation of neuroinflammatory markers of astrogliosis and microgliosis, loss of mossy fibers, and hippocampal granule cell dispersion. Furthermore, prolonged inhibition of ΔFosB using a ΔJunD construct to block ΔFosB signaling in a mouse model of Alzheimer's disease, that exhibits spontaneous recurrent seizures, led to similar findings, with increased neuroinflammation and decreased NPY expression in mossy fibers. Together, these data suggest that seizure-induced ΔFosB, regardless of seizure-etiology, is part of a homeostatic mechanism that protects the epileptic brain from further deterioration.

SV2B defines a subpopulation of synaptic vesicles.

Synaptic vesicles can undergo several modes of exocytosis, endocytosis, and trafficking within individual synapses, and their fates may be linked to differences in the vesicular protein composition. Here, we mapped the intrasynaptic distribution of the synaptic vesicle proteins SV2B and SV2A in glutamatergic synapses of the hippocampus using three-dimensional electron microscopy. SV2B is almost completely absent from both docked vesicles and a distinct cluster of vesicles found near the active zone. In contrast, SV2A was found in all domains of the synapse and was slightly enriched near the active zone. SV2B and SV2A were found on the membrane in the peri-active zone, suggesting recycling from both clusters of vesicles. SV2B knockout mice displayed an increased seizure induction threshold only in a model employing high-frequency stimulation. Our data show that glutamatergic synapses generate molecularly distinct populations of synaptic vesicles and are able to maintain them at steep spatial gradients. The almost complete absence of SV2B from vesicles at the active zone of wildtype mice may explain why SV2A has been found to be more important for vesicle release.

The cyclin-dependent kinase inhibitor p57Kip2 regulates cell cycle exit, differentiation, and migration of embryonic cerebral cortical precursors.

Mounting evidence indicates cyclin-dependent kinase (CDK) inhibitors (CKIs) of the Cip/Kip family, including p57(Kip2) and p27(Kip1), control not only cell cycle exit but also corticogenesis. Nevertheless, distinct activities of p57(Kip2) remain poorly defined. Using in vivo and culture approaches, we show p57(Kip2) overexpression at E14.5-15.5 elicits precursor cell cycle exit, promotes transition from proliferation to neuronal differentiation, and enhances process outgrowth, while opposite effects occur in p57(Kip2)-deficient precursors. Studies at later ages indicate p57(Kip2) overexpression also induces precocious glial differentiation, suggesting stage-dependent effects. In embryonic cortex, p57(Kip2) overexpression advances cell radial migration and alters postnatal laminar positioning. While both CKIs induce differentiation, p57(Kip2) was twice as effective as p27(Kip1) in inducing neuronal differentiation and was not permissive to astrogliogenic effects of ciliary neurotrophic factor, suggesting that the CKIs differentially modulate cell fate decisions. At molecular levels, although highly conserved N-terminal regions of both CKIs elicit cycle withdrawal and differentiation, the C-terminal region of p57(Kip2) alone inhibits in vivo migration. Furthermore, p57(Kip2) effects on neurogenesis and gliogenesis require the N-terminal cyclin/CDK binding/inhibitory domains, while previous p27(Kip1) studies report cell cycle-independent functions. These observations suggest p57(Kip2) coordinates multiple stages of corticogenesis and exhibits distinct and common activities compared with related family member p27(Kip1).

Aß42 oligomers trigger synaptic loss through CAMKK2-AMPK-dependent effectors coordinating mitochondrial fission and mitophagy.

During the early stages of Alzheimer's disease (AD) in both mouse models and human patients, soluble forms of Amyloid-ß 1-42 oligomers (Aß42o) trigger loss of excitatory synapses (synaptotoxicity) in cortical and hippocampal pyramidal neurons (PNs) prior to the formation of insoluble amyloid plaques. In a transgenic AD mouse model, we observed a spatially restricted structural remodeling of mitochondria in the apical tufts of CA1 PNs dendrites corresponding to the dendritic domain where the earliest synaptic loss is detected in vivo. We also observed AMPK over-activation as well as increased fragmentation and loss of mitochondrial biomass in Ngn2-induced neurons derived from a new APPSwe/Swe knockin human ES cell line. We demonstrate that Aß42o-dependent over-activation of the CAMKK2-AMPK kinase dyad mediates synaptic loss through coordinated phosphorylation of MFF-dependent mitochondrial fission and ULK2-dependent mitophagy. Our results uncover a unifying stress-response pathway causally linking Aß42o-dependent structural remodeling of dendritic mitochondria to synaptic loss.

Monitoring of a progressive functional dopaminergic deficit in the A53T-AAV synuclein rats by combining 6-[18F]fluoro-L-m-tyrosine imaging and motor performances analysis.

With the emergence of disease-modifying therapies for Parkinson's disease, reliable longitudinal markers are needed to quantify pathology and demonstrate disease progression. We developed the A53T-AAV rat model of synucleinopathy by combining longitudinal measures over 12 weeks. We first characterized the progression of the motor and dopaminergic deficits. Then, we monitored the disease progression using the [18F]FMT Positron Emission Tomography (PET) radiotracer. The nigral injection of A53T-AAV led to an increase in phosphorylated α-synuclein on S129, a progressive accumulation of α-synuclein aggregates, and a decrease of dopaminergic function associated with a deterioration of motor activity. The longitudinal monitoring of A53T-AAV rats with [18F]FMT PET showed a progressive reduction of the Kc outcome parameter in the caudate putamen from the lesioned side. Interestingly, the progressive reduction in the [18F]FMT PET signal correlated with defects in the stepping test. In conclusion, we established a progressive rat model of α-synuclein pathology which monitors the deficit longitudinally using both the [18F]FMT PET tracer and behavioral parameters, 2 features that have strong relevance for translational approaches.

Insulin-like growth factor-1 promotes G(1)/S cell cycle progression through bidirectional regulation of cyclins and cyclin-dependent kinase inhibitors via the phosphatidylinositol 3-kinase/Akt pathway in developing rat cerebral cortex.

Although survival-promoting effects of insulin-like growth factor-1 (IGF-1) during neurogenesis are well characterized, mitogenic effects remain less well substantiated. Here, we characterize cell cycle regulators and signaling pathways underlying IGF-1 effects on embryonic cortical precursor proliferation in vitro and in vivo. In vitro, IGF-1 stimulated cell cycle progression and increased cell number without promoting cell survival. IGF-1 induced rapid increases in cyclin D1 and D3 protein levels at 4 h and cyclin E at 8 h. Moreover, p27(KIP1) and p57(KIP2) expression were reduced, suggesting downregulation of negative regulators contributes to mitogenesis. Furthermore, the phosphatidylinositol 3-kinase (PI3K)/Akt pathway specifically underlies IGF-1 activity, because blocking this pathway, but not MEK (mitogen-activated protein kinase kinase)/ERK (extracellular signal-regulated kinase), prevented mitogenesis. To determine whether mechanisms defined in culture relate to corticogenesis in vivo, we performed transuterine intracerebroventricular injections. Whereas blockade of endogenous factor with anti-IGF-1 antibody decreased DNA synthesis, IGF-1 injection stimulated DNA synthesis and increased the number of S-phase cells in the ventricular zone. IGF-1 treatment increased phospho-Akt fourfold at 30 min, cyclins D1 and E by 6 h, and decreased p27(KIP1) and p57(KIP2) expression. Moreover, blockade of the PI3K/Akt pathway in vivo decreased DNA synthesis and cyclin E, increased p27(KIP1) and p57(KIP2) expression, and prevented IGF-1-induced cyclin E mRNA upregulation. Finally, IGF-1 injection in embryos increased postnatal day 10 brain DNA content by 28%, suggesting a role for IGF-1 in brain growth control. These results demonstrate a mitogenic role for IGF-1 that tightly controls both positive and negative cell cycle regulators, and indicate that the PI3K/Akt pathway mediates IGF-1 mitogenic signaling during corticogenesis.

A systems-level framework for drug discovery identifies Csf1R as an anti-epileptic drug target.

The identification of drug targets is highly challenging, particularly for diseases of the brain. To address this problem, we developed and experimentally validated a general computational framework for drug target discovery that combines gene regulatory information with causal reasoning ("Causal Reasoning Analytical Framework for Target discovery"-CRAFT). Using a systems genetics approach and starting from gene expression data from the target tissue, CRAFT provides a predictive framework for identifying cell membrane receptors with a direction-specified influence over disease-related gene expression profiles. As proof of concept, we applied CRAFT to epilepsy and predicted the tyrosine kinase receptor Csf1R as a potential therapeutic target. The predicted effect of Csf1R blockade in attenuating epilepsy seizures was validated in three pre-clinical models of epilepsy. These results highlight CRAFT as a systems-level framework for target discovery and suggest Csf1R blockade as a novel therapeutic strategy in epilepsy. CRAFT is applicable to disease settings other than epilepsy.

Identification and expression of a new splicing variant of FAD-sulfhydryl oxidase in adult rat brain.

Flavoproteins of the quiescin/sulfhydryl oxidase (QSOX) family catalyze oxidation of peptide and protein thiols to disulfides with the reduction of oxygen to hydrogen peroxide. We report here the molecular cloning of a new putative sulfhydryl oxidase cDNA, rQSOX-L (GenBank Accession no ), from adult rat brain and its expression studied by RT-PCR, Northern and Western blots in rat tissues. DNA-sequencing demonstrated the existence of two cDNAs in rat cortex, corresponding to a long transcript (rQSOX-L) and a short transcript (rQSOX-S) which differed by 851 nucleotides due to alternative splicing. The new transcript, rQSOX-L (3356 nucleotides), was specifically expressed in brain, hypophysis, heart, testis and seminal vesicle. The distribution of this variant is not homogeneous in the different tissues studied and suggests a complex gene regulation. The full-length rQSOX-L cDNA has an open reading frame of 2250-bp encoding a protein of 750 amino acids that contains a signal peptide sequence, a protein-disulfide-isomerase-type thioredoxin and ERV1-ALR domains and a long form specific C-terminal extension. The rQSOX-L protein is highly homologous to members of the sulfhydryl oxidase/Quiescin family and contains particularly two potential sites for N-glycosylation. This protein isoform was specifically detected in rat brain tissues in opposition to the low molecular form that was ubiquitous. Matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis of the immunoprecipitate tryptic fragments allowed the identification of rQSOX-L protein.

Ontogenesis of the sulfhydryl oxidase QSOX expression in rat brain.

The spatiotemporal pattern of distribution of the sulfhydryl oxidase QSOX throughout ontogeny was mapped in rat brain using immunohistochemistry. The enzyme was detected on embryonic day (E) 12 in the dawning mantle layer, but the adult-like pattern was acquired postnatally around day 30 (P30). Throughout ontogenesis, rQSOX was detected in immature and mature neurons, but not in glial cells. The rQSOX developmental pattern can be divided into four periods: on E12 the enzyme was detected in the brainstem, more precisely in motoneurons; later (E16), rQSOX-positive cells were also observed in the forebrain, in the caudoputamen, and the subventricular zone. During late embryogenesis (E18-20), the amount of rQSOX cells considerably increased throughout the brain; they initially appeared in the hippocampus, then in the isocortex. From birth onwards, complex modifications of the rQSOX distribution occurred leading to the adult pattern by P30. Although rQSOX exhibits an overall increasing spatiotemporal pattern of distribution, different expression strategies were distinguished depending on the cell type or brain area. By comparing the rQSOX ontogeny with data on neurogenesis and brain histogenesis, we hypothesize that the enzyme could play a role in guiding migrating cells, their settling, and neuronal maturation, e.g., during outgrowth and synaptogenesis.

Expression of the sulfhydryl oxidase ALR (Augmenter of Liver Regeneration) in adult rat brain.

Mammalian Augmenter of Liver Regeneration protein (ALR) was first identified as a secondary growth factor involved in liver regeneration. Its sulfhydryl oxidase activity and involvement in iron homeostasis have been recently demonstrated. ALR is expressed in a broad range of peripheral organs, and initial experiments gave also evidence for the occurrence of this protein in brain. In the present study, we investigated in detail the expression of ALR in rat brain sections and determined its cellular and subcellular localizations using biomolecular and immunohistochemical procedures. As shown by Northern blot, ALR is differentially expressed throughout the rat brain, with the highest mRNA levels in the cerebellum and diencephalon. High protein levels were also detected in the brain and cerebellum by Western blot. ALR immunoreactivity was found in neurons and glial cells throughout brain rostrocaudal extent. Labeled astrocytes were particularly abundant in the white matter, and immunoreactive neurons were observed in several regions including the olfactory bulb, isocortex, hippocampal formation, amygdala, thalamus, hypothalamus, some nuclei of the brainstem and cerebellum. In neurons, immunoelectron microscopy showed the protein in the nucleus and mainly in mitochondria. These subcellular localizations may correlate with the occurrence of two ALR protein isoforms in the brain. In the central nervous system, the enzyme might be of importance in heavy metal homeostasis whose dysregulation can induce neurodegenerative disorders.

FAD-linked sulfhydryl oxidase QSOX: topographic, cellular, and subcellular immunolocalization in adult rat central nervous system.

The distribution of the sulfhydryl oxidase QSOX in the rat brain was mapped using immunohistochemistry. QSOX is specifically expressed by neurons throughout the rostrocaudal extent of the brain as well as in the spinal cord. Although a majority of neurons express QSOX, different intensities of labeling were observed depending on the area: the strongest labeling was observed in the olfactory bulbs, isocortex, hippocampus, basal telencephalon, several thalamic and hypothalamic nuclei, cerebellum, and numerous brainstem nuclei. This study also describes the ultrastructural localization of QSOX in neuronal cells and demonstrates that the enzyme is associated with the Golgi apparatus. Finally, selected double immunohistochemistry showed that in the hypothalamus the highest levels of QSOX labeling were colocalized in neuron populations that express disulfide-bounded neuropeptides. These observations are consistent with a role of the enzyme in secreted peptide/protein folding. Data presented herein will serve as a basis for further investigations of the physiological function of QSOX in the central nervous system.

Expression of SOx-2, a member of the FAD-dependent sulfhydryl oxidase/quiescin Q6 gene family, in rat brain.

Sulfhydryl oxidases belonging to the FAD-dependent sulfhydryl oxidase/quiescin Q6 family were previously reported in rat peripheral organs but they were not detected in brain. In the present study, by using reverse transcription-polymerase chain reaction and northern blot analysis, we clearly show an ubiquitous expression of the gene in brain; moreover, while only one transcript was present in peripheral organs, at least two transcripts were detected in brain, suggesting a tissue-specific splicing of its mRNA. The shorter one, likely corresponding to the mRNA identified from rat seminal vesicles, was highly expressed in diencephalon and telencephalon. The finding of gene expression in brain is relevant, since its dysregulation could lead to oxidative stress, a causative factor in the pathogenesis of neurodegenerative diseases.

Orexin/hypocretin neurons: chemical phenotype and possible interactions with melanin-concentrating hormone neurons.

We showed earlier that a specific neuron population of the rat lateral hypothalamus, differing from the codistributed melanin-concentrating hormone (MCH) neurons, express both dynorphin (DYN) and secretogranin II (SgII) genes. We demonstrated later that this population corresponds in fact to the newly identified orexin/hypocretin (OX/Hcrt) neurons. In the present study, by revisiting the chemical phenotype of these neurons, we confirm that all of them contain DYN B- and SgII-immunoreactive materials. The roles played by these peptide/protein in OX/Hcrt neurons are still unclear. Double immunocytochemical stainings highlight putative somasomatic, axosomatic and axodendritic contacts between OX/Hcrt and MCH neurons. Adding OX/Hcrt to the culture medium of hypothalamic slices from 8-day-old rats results either in a significant increase of MCH mRNA after 24 h survival or a strong fall after 10 days culture. These results taken together suggest that OX/Hcrt can directly and/or indirectly affect MCH expression, and that both OX/Hcrt and MCH neuron populations interact to respond in a coordinated manner to central and peripheral signals.

Involvement of 'stress-response' kinase pathways in Alzheimer's disease progression.

Alzheimer's disease (AD) is the most prevalent cause of dementia, affecting more than 25 million people worldwide. Current models of the pathophysiological mechanisms of AD suggest that the accumulation of soluble oligomeric forms of amyloid-ß (Aß) peptides causes early loss of excitatory synapses and impairs synaptic plasticity. The signaling pathways mediating Aß oligomer-induced impairment of synaptic plasticity and loss of excitatory synapses are only beginning to be unraveled. Here, we review recent evidence supporting the critical contribution of conserved 'stress-response' kinase pathways in AD progression.