Neuroanatomical and morphometric study of S100ß positive astrocytes in the entorhinal cortex during ageing in the 3xTg-Alzehimer's disease mouse model.

Astrocytes contribute to the progression of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we report the neuroanatomical and morphometric analysis of astrocytes in the entorhinal cortex (EC) of the aged wild type (WT) and triple transgenic (3xTg-AD) mouse model of AD. Using 3D confocal microscopy, we determined the surface area and volume of positive astrocytic profiles in male mice (WT and 3xTg-AD) from 1 to 18 months of age. We showed that S100ß-positive astrocytes were equally distributed throughout the entire EC in both animal types and showed no changes in Nv (number of cells/mm3) nor in their distribution at the different ages studied. These positive astrocytes, demonstrated an age-dependent gradual increase in their surface area and in their volume starting at 3 months of age, in both WT and 3xTg-AD mice. This last group demonstrated a large increase in both surface area and volume at 18 months of age when the burden of pathological hallmarks of AD is present (69.74% to 76.73% in the surface area and the volume, for WT and 3xTg-AD mice respectively). We observed that these changes were due to the enlargement of the cell processes and to less extend the somata. In fact, the volume of the cell body was increased by 35.82% in 18-month-old 3xTg-AD compared to WT. On the other hand, the increase on the astrocytic processes were detected as soon as 9 months of age where we found an increase of surface area and volume (36.56% and 43.73%, respectively) sustained till 18 month of age (93.6% and 113.78%, respectively) when compared age-matched non-Tg mice. Moreover, we demonstrated that these hypertrophic S100ß-positive astrocytes were mainly associated with Aß plaques. Our results show a severe atrophy in GFAP cytoskeleton in all cognitive areas; whilst within the EC astrocytes independent to this atrophy show no changes in GS and S100ß; which can play a key role in the memory impairment.

Analysis of the mechanism of Sophorae Flavescentis Radix in the treatment of intractable itching based on network pharmacology and molecular docking.

OBJECTIVE: Sophorae Flavescentis Radix (Kuh-seng, SFR), a Traditional Chinese Medicine (TCM), is widely used alone or within a TCM formula to treat pruritus, especially histamine-independent intractable itching. In the previous study, potential antipruritic active components of the SFR were screened based on cell membrane immobilized chromatography (CMIC), revealing oxymatrine (OMT) as an antipruritic agent. However, the low oral bioavailability (OB) of OMT cannot explain the antipruritic effect of SFR when administered orally in clinic. In this study, we investigated the antipruritic effects and underlying mechanisms of orally administered SFR. MATERIALS AND METHODS: A network pharmacology and molecular docking were employed to screen the active components of SFR and predict their binding to disease-related target proteins, while the potential mechanisms were explored with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The binding energy between components and target proteins was calculated by molecular docking. RESULTS: The SFR-components-targets-intractable itching Protein-Protein Interactions (PPI) network was established, and 22 active components and 42 targets were screened. The GO enrichment analysis showed that the key target genes of SFR were related to nuclear receptors, transcription factors, and steroid hormone receptors. The results of the KEGG enrichment pathway analysis include Hepatitis B, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, advanced glycation end product (AGE)-receptor for AGE (RAGE) signaling pathway in diabetic complications, etc. Molecular docking showed that three key target proteins in the network, the vascular endothelial growth factor A (VEGFA), epidermal growth factor receptor (EGFR) and caspase-3 (CASP3), have higher binding activities with inermine, phaseolin and kushenol O, respectively; the binding energy of each pair is stronger than that of the target protein-corresponding inhibitors. CONCLUSIONS: The complexity of the SFR-components-targets-intractable itching network demonstrated the holistic treatment effect of SFR on intractable itching. The partial coherence between results screened by CMIC in the previous study and network pharmacology demonstrated the potential of network pharmacology in active component screening. Inermine screened from both CMIC and network pharmacology is a VEGFA inhibitor, which possibly accounts for the antipruritic effect of orally administered SFR.

Astrocytes and major depression: The purinergic avenue.

Major depressive disorder (MDD) is one of the most prevalent psychiatric illnesses worldwide which impairs the social functioning of the afflicted patients. Astrocytes promote homeostasis of the CNS and provide defense against various types of harmful influences. Increasing evidence suggests that the number, morphology and function of astrocytes are deteriorated in the depressed brain and the malfunction of the astrocytic purinergic system appears to participate in the pathophysiology of MDD. Adenosine 5'-triphosphate (ATP) released from astrocytes modulates depressive-like behavior in animal models and probably also clinical depression in patients. Astrocytes possess purinergic receptors, such as adenosine A2A receptors (Rs), and P2X7, P2Y1, and P2Y11Rs, which mediate neuroinflammation, neuro(glio)transmission, and synaptic plasticity in depression-relevant areas of the brain (e.g. medial prefrontal cortex, hippocampus, amygdala nuclei). By contrast, astrocytic A1Rs are neuroprotective and immunosuppressive. In the present review, we shall discuss the release of purines from astrocytes, and the expression/function of astrocytic purinergic receptors. Subsequently, we shall review in more detail novel evidence indicating that the dysregulation of astrocytic purinergic signaling actively contributes to the pathophysiology of depression and shall discuss possible therapeutic options based on knowledge recently acquired in this field.

Connexins as therapeutic targets in neurological and neuropsychiatric disorders.

Astrocytes represent the reticular part of the central nervous system; gap junctions formed by connexins Cx43, Cx30- and Cx26 provide for homocellular astrocyte-astrocyte coupling, whereas connexins Cx30, Cx32, Cx43, and Cx47 connect astrocytes and oligodendrocytes. Astroglial networks are anatomically and functionally segregated being homologous to neuronal ensembles. Connexons, gap junctions and hemichannels (unpaired connexons) are affected in various neuropathologies from neuropsychiatric to neurodegenerative diseases. Manipulation of astrocytic connexins modulates the size and outreach of astroglial syncytia thus affecting astroglial homeostatic support. Modulation of astrocytic connexin significantly modifies pharmacological profile of many CNS drugs, which represents an innovative therapeutic approach for CNS disorders; this approach is now actively tested in pre-clinical and clinical studies. Wide combination of connexin modulators with CNS drugs open new promising perspectives for fundamental studies and therapeutic strategies.

Correction: Aberrant iPSC-derived human astrocytes in Alzheimer's disease.

The original version of this Article contained an error in Fig. 1, in which a number of incorrect fluorescence images were inadvertently incorporated into the panel. This has been corrected in both the PDF and HTML versions of the Article.

Anti-Atherosclerosis Effect of Angong Niuhuang Pill via Regulating Th17/Treg Immune Balance and Inhibiting Chronic Inflammatory on ApoE-/- Mice Model of Early and Mid-Term Atherosclerosis.

Angong Niuhuang Pill (ANP) is a well-known patented Chinese medicine which is used for hundreds of years for treating the central nervous system diseases. Atherosclerosis is a poly-aetiological chronic inflammatory vascular disease. Preventing inflammation is fundamental for treating atherosclerosis in early stages. In this study, we investigated the protective effects and possible mechanisms of ANP action on a high-fat diet induced early and mid-term atherosclerosis ApoE-/- mice. The effects of ANP were compared with accepted drug simvastatin. Twelve male C57BL/6J mice were used as the control group, and 60 male ApoE-/- mice were randomly divided into five groups: Model group, Simvastatin group, Low-, Medium-, and High-dose ANP group these groups received, respectively, saline, simvastatin (3.0mg/kg), low-dose ANP (0.25 g/kg), medium-dose ANP (0.50 g/kg), and high-dose ANP (1.0 g/kg), once every other day for 10 weeks. After administration, serum biochemical indices were detected by the automatic biochemical analyzer, the concentrations of IL-6 and IL-10 in the serum were assayed by ELISA, expression levels of IL-1ß, TNF-α, MMP-2, MMP-9, CCL2, and its receptor CCR2 in the full-length aorta, and expression levels of transcription factors Foxp3, RORγt in the spleen were assayed via western blotting and RT-qPCR. Flow cytometry was used to analyze Th17 cells and Treg cells. Pathological and histological analysis was completed on aortic root. ANP decreased LDL/HDL ratio, concentrations of IL-6 while increased IL-10 in serum. Moreover, ANP down-regulated the expression levels of IL-1ß, TNF-α, MMP-2, MMP-9, CCL2, and CCR2 receptor in the full-length aorta. In addition, ANP decreased Th17 cells and expression levels of transcription factor RORγt, increased Treg cells and expression levels of transcription factor Foxp3. ANP decreased content of collagen fibers and infiltration of inflammatory cells in the aortic root. In conclusion, we demonstrated that ANP has anti-atherosclerosis effects on a high-fat diet induced ApoE-/- mice early and mid-term AS model via regulating Th17/Treg balance, inhibiting chronic inflammation, reducing plaque collagen fibers, and reducing inflammatory cells infiltration, to exert its multi-channel multi-target anti-early and mid-term AS effects.

Astroglial vesicular network: evolutionary trends, physiology and pathophysiology.

Intracellular organelles, including secretory vesicles, emerged when eukaryotic cells evolved some 3 billion years ago. The primordial organelles that evolved in Archaea were similar to endolysosomes, which developed, arguably, for specific metabolic tasks, including uptake, metabolic processing, storage and disposal of molecules. In comparison with prokaryotes, cell volume of eukaryotes increased by several orders of magnitude and vesicle traffic emerged to allow for communication between distant intracellular locations. Lysosomes, first described in 1955, a prominent intermediate of endo- and exocytotic pathways, operate virtually in all eukaryotic cells including astroglia, the most heterogeneous type of homeostatic glia in the central nervous system. Astrocytes support neuronal network activity in particular through elaborated secretion, based on a complex intracellular vesicle network dynamics. Deranged homeostasis underlies disease and astroglial vesicle traffic contributes to the pathophysiology of neurodegenerative (Alzheimer's disease, Huntington's disease), neurodevelopmental diseases (intellectual deficiency, Rett's disease) and neuroinfectious (Zika virus) disorders. This review addresses astroglial cell-autonomous vesicular traffic network, as well as its into primary and secondary vesicular network defects in diseases, and considers this network as a target for developing new therapies for neurological conditions.

Aberrant iPSC-derived human astrocytes in Alzheimer's disease.

The pathological potential of human astroglia in Alzheimer's disease (AD) was analysed in vitro using induced pluripotent stem cell (iPSC) technology. Here, we report development of a human iPSC-derived astrocyte model created from healthy individuals and patients with either early-onset familial AD (FAD) or the late-onset sporadic form of AD (SAD). Our chemically defined and highly efficient model provides >95% homogeneous populations of human astrocytes within 30 days of differentiation from cortical neural progenitor cells (NPCs). All astrocytes expressed functional markers including glial fibrillary acidic protein (GFAP), excitatory amino acid transporter-1 (EAAT1), S100B and glutamine synthetase (GS) comparable to that of adult astrocytes in vivo. However, induced astrocytes derived from both SAD and FAD patients exhibit a pronounced pathological phenotype, with a significantly less complex morphological appearance, overall atrophic profiles and abnormal localisation of key functional astroglial markers. Furthermore, NPCs derived from identical patients did not show any differences, therefore, validating that remodelled astroglia are not as a result of defective neural intermediates. This work not only presents a novel model to study the mechanisms of human astrocytes in vitro, but also provides an ideal platform for further interrogation of early astroglial cell autonomous events in AD and the possibility of identification of novel therapeutic targets for the treatment of AD.

ATP from synaptic terminals and astrocytes regulates NMDA receptors and synaptic plasticity through PSD-95 multi-protein complex.

Recent studies highlighted the importance of astrocyte-secreted molecules, such as ATP, for the slow modulation of synaptic transmission in central neurones. Biophysical mechanisms underlying the impact of gliotransmitters on the strength of individual synapse remain, however, unclear. Here we show that purinergic P2X receptors can bring significant contribution to the signalling in the individual synaptic boutons. ATP released from astrocytes facilitates a recruitment of P2X receptors into excitatory synapses by Ca(2+)-dependent mechanism. P2X receptors, co-localized with NMDA receptors in the excitatory synapses, can be activated by ATP co-released with glutamate from pre-synaptic terminals and by glia-derived ATP. An activation of P2X receptors in turn leads to down-regulation of postsynaptic NMDA receptors via Ca(2+)-dependent de-phosphorylation and interaction with PSD-95 multi-protein complex. Genetic deletion of the PSD-95 or P2X4 receptors obliterated ATP-mediated down-regulation of NMDA receptors. Impairment of purinergic modulation of NMDA receptors in the PSD-95 mutants dramatically decreased the threshold of LTP induction and increased the net magnitude of LTP. Our findings show that synergistic action of glia- and neurone-derived ATP can pre-modulate efficacy of excitatory synapses and thereby can have an important role in the glia-neuron communications and brain meta-plasticity.

Astrocytic vesicles and gliotransmitters: Slowness of vesicular release and synaptobrevin2-laden vesicle nanoarchitecture.

Neurotransmitters released at synapses activate neighboring astrocytes, which in turn, modulate neuronal activity by the release of diverse neuroactive substances that include classical neurotransmitters such as glutamate, GABA or ATP. Neuroactive substances are released from astrocytes through several distinct molecular mechanisms, for example, by diffusion through membrane channels, by translocation via plasmalemmal transporters or by vesicular exocytosis. Vesicular release regulated by a stimulus-mediated increase in cytosolic calcium involves soluble N-ethyl maleimide-sensitive fusion protein attachment protein receptor (SNARE)-dependent merger of the vesicle membrane with the plasmalemma. Up to 25 molecules of synaptobrevin 2 (Sb2), a SNARE complex protein, reside at a single astroglial vesicle; an individual neuronal, i.e. synaptic, vesicle contains ∼70 Sb2 molecules. It is proposed that this paucity of Sb2 molecules in astrocytic vesicles may determine the slow secretion. In the present essay we shall overview multiple aspects of vesicular architecture and types of vesicles based on their cargo and dynamics in astroglial cells.

Astrocytes in physiological aging and Alzheimer's disease.

Astrocytes are fundamental for homoeostasis, defence and regeneration of the central nervous system. Loss of astroglial function and astroglial reactivity contributes to the aging of the brain and to neurodegenerative diseases. Changes in astroglia in aging and neurodegeneration are highly heterogeneous and region-specific. In animal models of Alzheimer's disease (AD) astrocytes undergo degeneration and atrophy at the early stages of pathological progression, which possibly may alter the homeostatic reserve of the brain and contribute to early cognitive deficits. At later stages of AD reactive astrocytes are associated with neurite plaques, the feature commonly found in animal models and in human diseased tissue. In animal models of the AD reactive astrogliosis develops in some (e.g. in the hippocampus) but not in all regions of the brain. For instance, in entorhinal and prefrontal cortices astrocytes do not mount gliotic response to emerging ß-amyloid deposits. These deficits in reactivity coincide with higher vulnerability of these regions to AD-type pathology. Astroglial morphology and function can be regulated through environmental stimulation and/or medication suggesting that astrocytes can be regarded as a target for therapies aimed at the prevention and cure of neurodegenerative disorders.

Ammonium increases Ca(2+) signalling and upregulates expression of Cav1.2 gene in astrocytes in primary cultures and in the in vivo brain.

AIM: The primary aim of this study was to identify the effects of hyperammonaemia on functional expression of Cav1.2 L-type Ca(2+) channels in astroglia. METHODS: Primary cultures of mouse astrocytes were used to study effects of chronic treatment (1-5 days) with ammonium chloride, at 1, 3 and 5 mm on depolarization-induced increases in free cytosolic Ca(2+) concentration ([Ca(2+)]i , measured with Fura-2 based microfluorimetry) in control conditions and following treatment with the L-type Ca(2+) channel inhibitor, nifedipine, or with ryanodine receptor inhibitor, ryanodine. Expression of Cav1.2 mRNA was identified with RT-PCR, whereas protein content was determined by Western blotting. Sustained hyperammonaemia in vivo was induced by daily injections of urease (33 units kg body weight(-1), i.p.) for 3 days. RESULTS: Depolarization-induced [Ca(2+)]i transients sensitive to nifedipine (peak of the response) and to ryanodine (plateau phase) were significantly increased in astrocytes chronically exposed to ammonium. The ammonium-induced increase in Ca(2+) influx in astrocytes resulted from an upregulation of Cav1.2 channel's expression detected at mRNA and protein levels. Increase in Cav1.2 expression was prevented by ouabain antagonist canrenone. Similar upregulation of Cav1.2 gene expression was found in the brains of adult mice subjected to intraperitoneal injection of urease. In transgenic mice tagged with an astrocyte-specific or neurone-specific markers and treated with intraperitoneal injections of urease, the fluorescence-activated cell sorting of neurones and astrocytes demonstrated that Cav1.2 mRNA expression was upregulated in astrocytes, but not in neurones. CONCLUSIONS: Ammonium-induced deregulation of astroglial Ca(2+) signalling, is, in part, associated with upregulation of Cav1.2 L-type calcium channels.

Microglial response to Alzheimer's disease is differentially modulated by voluntary wheel running and enriched environments.

Alzheimer's disease (AD) is an untreatable neurodegenerative disease that deteriorates memory. Increased physical/cognitive activity reduces dementia risk by promoting neuronal and glial response. Although few studies have investigated microglial response in wild-type rodents following exposure to physical/cognitive stimulation, environmental-induced changes of microglia response to AD have been neglected. We investigated effects of running (RUN) and enriched (ENR) environments on numerical density (N v, #/mm(3)) and morphology of microglia in a triple transgenic (3×Tg-AD) mouse model of AD that closely mimics AD pathology in humans. We used immunohistochemical approach to characterise microglial domain by measuring their overall cell surface, volume and somata volume. 3×Tg-AD mice housed in standard control (STD) environment showed significant increase in microglial N v (11.7 %) in CA1 stratum lacunosum moleculare (S.Mol) of the hippocampus at 12 months compared to non-transgenic (non-Tg) animals. Exposure to combined RUN and ENR environments prevented an increase in microglial N v in 3×Tg-AD and reduced microglial numbers to non-Tg control levels. Interestingly, 3×Tg-AD mice housed solely in ENR environment displayed significant decrease in microglial N v in CA1 subfield (9.3 % decrease), stratum oriens (11.5 % decrease) and S.Mol (7.6 % decrease) of the hippocampus compared to 3×Tg-AD mice housed in STD environment. Morphological analysis revealed microglial hypertrophy due to pronounced increase in microglia surface, volume and somata volume (61, 78 and 41 %) in 3×Tg-AD mice housed in RUN (but not in ENR) compared to STD environment. These results indicate that exposure to RUN and ENR environments have differential effects on microglial density and activation-associated changes in microglial morphology.

Purinergic signaling mediated by P2X7 receptors controls myelination in sciatic nerves.

Adenosine-5'-triphosphate, the physiological ligand of P2X receptors, is an important factor in peripheral nerve development. P2X7 receptor is expressed in Schwann cells (SCs), but the specific effects of P2X7 purinergic signaling on peripheral nerve development, myelination, and function are largely unknown. In this study, sciatic nerves from P2X7 knockout mice were analyzed for altered expression of myelin-associated proteins and for alterations in nerve morphology. Immunohistochemical analyses revealed that, in the wild-type peripheral nerves, the P2X7 receptor was localized mainly in myelinating SCs, with only a few immunopositive nonmyelinating SCs. Complete absence of P2X7 receptor protein was confirmed in the sciatic nerves of the knockout mice by Western blot and immunohistochemistry. Western blot analysis revealed that expression levels of the myelin proteins protein zero and myelin-associated glycoprotein are reduced in P2X7 knockout nerves. In accordance with the molecular results, transmission electron microscopy analyses revealed that P2X7 knockout nerves possess significantly more unmyelinated axons, contained in a higher number of Remak bundles. The myelinating/nonmyelinating SC ratio was also decreased in knockout mice, and we found a significantly increased number of irregular fibers compared with control nerves. Nevertheless, the myelin thickness in the knockout was unaltered, suggesting a stronger role for P2X7 in determining SC maturation than in myelin formation. In conclusion, we present morphological and molecular evidence of the importance of P2X7 signaling in peripheral nerve maturation and in determining SC commitment to a myelinating phenotype.

Altered expression of Alzheimer's disease-related genes in the cerebellum of autistic patients: a model for disrupted brain connectome and therapy.

Autism and Alzheimer's disease (AD) are, respectively, neurodevelopmental and degenerative diseases with an increasing epidemiological burden. The AD-associated amyloid-ß precursor protein-α has been shown to be elevated in severe autism, leading to the 'anabolic hypothesis' of its etiology. Here we performed a focused microarray analysis of genes belonging to NOTCH and WNT signaling cascades, as well as genes related to AD and apoptosis pathways in cerebellar samples from autistic individuals, to provide further evidence for pathological relevance of these cascades for autism. By using the limma package from R and false discovery rate, we demonstrated that 31% (116 out of 374) of the genes belonging to these pathways displayed significant changes in expression (corrected P-values <0.05), with mitochondria-related genes being the most downregulated. We also found upregulation of GRIN1, the channel-forming subunit of NMDA glutamate receptors, and MAP3K1, known activator of the JNK and ERK pathways with anti-apoptotic effect. Expression of PSEN2 (presinilin 2) and APBB1 (or F65) were significantly lower when compared with control samples. Based on these results, we propose a model of NMDA glutamate receptor-mediated ERK activation of α-secretase activity and mitochondrial adaptation to apoptosis that may explain the early brain overgrowth and disruption of synaptic plasticity and connectome in autism. Finally, systems pharmacology analyses of the model that integrates all these genes together (NOWADA) highlighted magnesium (Mg(2+)) and rapamycin as most efficient drugs to target this network model in silico. Their potential therapeutic application, in the context of autism, is therefore discussed.

Differentiation of adipose-derived stem cells into Schwann cell phenotype induces expression of P2X receptors that control cell death.

Schwann cells (SCs) are fundamental for development, myelination and regeneration in the peripheral nervous system. Slow growth rate and difficulties in harvesting limit SC applications in regenerative medicine. Several molecules, including receptors for neurosteroids and neurotransmitters, have been suggested to be implicated in regulating physiology and regenerative potential of SCs. Adipose-derived stem cells (ASCs) can be differentiated into SC-like phenotype (dASC) sharing morphological and functional properties with SC, thus representing a valid SC alternative. We have previously shown that dASC express γ-aminobutyric-acid receptors, which modulate their proliferation and neurotrophic potential, although little is known about the role of other neurotransmitters in ASC. In this study, we investigated the expression of purinergic receptors in dASC. Using reverse transriptase (RT)-PCR, western blot analyses and immunocytochemistry, we have demonstrated that ASCs express P2X3, P2X4 and P2X7 purinoceptors. Differentiation of ASCs towards glial phenotype was accompanied by upregulation of P2X4 and P2X7 receptors. Using Ca(2+)-imaging techniques, we have shown that stimulation of purinoceptors with adenosine 5'-triphosphate (ATP) triggers intracellular Ca(2+) signals, indicating functional activity of these receptors. Whole-cell voltage clamp recordings showed that ATP and BzATP induced ion currents that can be fully inhibited with specific P2X7 antagonists. Finally, using cytotoxicity assays we have shown that the increase of intracellular Ca(2+) leads to dASC death, an effect that can be prevented using a specific P2X7 antagonist. Altogether, these results show, for the first time, the presence of functional P2X7 receptors in dASC and their link with critical physiological processes such as cell death and survival. The presence of these novel pharmacological targets in dASC might open new opportunities for the management of cell survival and neurotrophic potential in tissue engineering approaches using dASC for nerve repair.

Increased densities of resting and activated microglia in the dentate gyrus follow senile plaque formation in the CA1 subfield of the hippocampus in the triple transgenic model of Alzheimer's disease.

Alzheimer's disease (AD) is an irreversible neurodegenerative disease that is characterised by the presence of ß-amyloid (Aß) plaques, neurofibrillary tangles (NFTs) and synaptic loss specifically in brain regions involved in learning and memory such as the neocortex and the hippocampus. Aß depositions in the form of neuritic plaques trigger activation of microglia that is believed to be a common neuropathological feature of AD brains. As an integral part of the hippocampus, the dentate gyrus (DG) plays an important role in cognitive function. Although post-mortem studies suggest later involvement of the DG into the AD progression, changes in microglia have not been studied in this subfield of the hippocampus. In the present study the numerical density (Nv, #/mm(3)) of both resting (identified by tomato lectin staining) and activated (identified by Mac-1 immunoreactivity) microglia was analysed in the molecular layer (ML) of the DG in the triple transgenic (3xTg-AD) mouse model of AD at different ages (9, 12 and 18 months). The 3xTg-AD mouse model of AD showed a significant increase in the Nv of resting (by 75%) and activated (by 67%) at 18 months of age compared to non-Tg controls. These results indicate a complex microglial remodelling during AD progression.

Amyloid-ß and Alzheimer's disease type pathology differentially affects the calcium signalling toolkit in astrocytes from different brain regions.

The entorhinal-hippocampal circuit is severely affected in Alzheimer's disease (AD). Here, we demonstrate that amyloid-ß (Aß) differentially affects primary cultured astrocytes derived from the entorhinal cortex (EC) and from the hippocampus from non-transgenic controls and 3xTg-AD transgenic mice. Exposure to 100 nM of Aß resulted in increased expression of the metabotropic glutamate receptor type 5 (mGluR5) and its downstream InsP3 receptor type 1 (InsP3R1) in hippocampal but not in EC astrocytes. Amplitudes of Ca(2+) responses to an mGluR5 agonist, DHPG, and to ATP, another metabotropic agonist coupled to InsP3Rs, were significantly increased in Aß-treated hippocampal but not in EC astrocytes. Previously we demonstrated that senile plaque formation in 3xTg-AD mice triggers astrogliosis in hippocampal but not in EC astrocytes. The different sensitivities of the Ca(2+) signalling toolkit of EC versus hippocampal astrocytes to Aß may account for the lack of astrogliosis in the EC, which in turn can explain the higher vulnerability of this region to AD.