Opposing effects of the purinergic P2X7 receptor on seizures in neurons and microglia in male mice.

BACKGROUND: The purinergic ATP-gated P2X7 receptor (P2X7R) is increasingly recognized to contribute to pathological neuroinflammation and brain hyperexcitability. P2X7R expression has been shown to be increased in the brain, including both microglia and neurons, in experimental models of epilepsy and patients. To date, the cell type-specific downstream effects of P2X7Rs during seizures remain, however, incompletely understood. METHODS: Effects of P2X7R signaling on seizures and epilepsy were analyzed in induced seizure models using male mice including the kainic acid model of status epilepticus and pentylenetetrazole model and in male and female mice in a genetic model of Dravet syndrome. RNA sequencing was used to analyze P2X7R downstream signaling during seizures. To investigate the cell type-specific role of the P2X7R during seizures and epilepsy, we generated mice lacking exon 2 of the P2rx7 gene in either microglia (P2rx7:Cx3cr1-Cre) or neurons (P2rx7:Thy-1-Cre). To investigate the protective potential of overexpressing P2X7R in GABAergic interneurons, P2X7Rs were overexpressed using adeno-associated virus transduction under the mDlx promoter. RESULTS: RNA sequencing of hippocampal tissue from wild-type and P2X7R knock-out mice identified both glial and neuronal genes, in particular genes involved in GABAergic signaling, under the control of the P2X7R following seizures. Mice with deleted P2rx7 in microglia displayed less severe acute seizures and developed a milder form of epilepsy, and microglia displayed an anti-inflammatory molecular profile. In contrast, mice lacking P2rx7 in neurons showed a more severe seizure phenotype when compared to epileptic wild-type mice. Analysis of single-cell expression data revealed that human P2RX7 expression is elevated in the hippocampus of patients with temporal lobe epilepsy in excitatory and inhibitory neurons. Functional studies determined that GABAergic interneurons display increased responses to P2X7R activation in experimental epilepsy. Finally, we show that viral transduction of P2X7R in GABAergic interneurons protects against evoked and spontaneous seizures in experimental temporal lobe epilepsy and in mice lacking Scn1a, a model of Dravet syndrome. CONCLUSIONS: Our results suggest a dual and opposing action of P2X7R in epilepsy and suggest P2X7R overexpression in GABAergic interneurons as a novel therapeutic strategy for acquired and, possibly, genetic forms of epilepsy.

Evaluation of prenatal calabash chalk geophagy on the developing brain of Wistar rats.

Calabash chalk (CaC) is an aluminium silicate hydroxide compound with heavy metal constituents, making it a potential neurotoxicant. Pregnant women often consume CaC as an antiemetic, which may interfere with the normal development of the foetal brain. Here, we evaluated the effects of CaC administration in pregnant rats on the brain of the offspring. Wistar rat dams were assigned to one of three groups: control, 200 mg/kg and 800 mg/kg of a CaC suspension. Administrations lasted 14 days (gestation days 7-20). On day 14, 5-bromo-2'-deoxyuridine (BrdU) was administered and dams were allowed to term. Behavioural tests were performed on different days as the pups matured, and they were sacrificed on post-natal days 30 and 60. Brains were processed for histology and Western blotting. Results showed no significant differences in surface righting reflex, cliff avoidance, negative geotaxis and open-field activity. No hippocampal and somatosensory cortical cytoarchitectonic alterations and no significant signs of glial fibrillary acidic protein (GFAP) activation were observed. Neuronal nuclei counts showed variability in the somatosensory cortex and hippocampus of the CaC group. BrdU-positive cells were significantly lower in the 200 mg/kg group and higher in the 800 mg/kg group. Doublecortin-X-positive cells were not different in all the CaC groups. Astrocytes and microglia Western blotting quantification confirmed no significant increase in pup glial cells in adulthood. Prenatal consumption of CaC at indicated dosages may not be deleterious to the developing brain, especially after cessation of exposure and during maturation of the animal. However, the differences in neuronal and glial populations may be due to their ability to cope with CaC.

A Practical Framework for Academics to Implement Public Engagement Interventions and Measure Their Impact.

Academic institutions have shown an increased interest in the so-called third mission to offer an impactful contribution to society. Indeed, public engagement programs ensure knowledge transfer and help to inspire positive public discourse. We aimed to propose a comprehensive framework for academic institutions planning to implement a public engagement intervention and to suggest potential indicators to measure its impact. To inform the framework development, we searched the literature on public engagement, the third mission, and design theory in electronic databases and additional sources (e.g., academic recommendations) and partnered with a communication agency offering non-academic advice. In line with this framework, we designed a public engagement intervention to foster scientific literacy in Italian youth, actively involving them in the development of the intervention. Our framework is composed of four phases (planning/design, implementation, immediate impact assessment, and medium- and long-term assessment). Impact indicators were subdivided into outcome variables that were immediately describable (e.g., changed understanding and awareness of the target population) and measurable only in the medium or long run (e.g., adoption of the intervention by other institutions). The framework is expected to maximize the impact of public engagement interventions and ultimately lead to better reciprocal listening and mutual understanding between academia and the public.

Gut microbiota modulates seizure susceptibility.

A bulk of data suggest that the gut microbiota plays a role in a broad range of diseases, including those affecting the central nervous system. Recently, significant differences in the intestinal microbiota of patients with epilepsy, compared to healthy volunteers, have been reported in an observational study. However, an active role of the intestinal microbiota in the pathogenesis of epilepsy, through the so-called "gut-brain axis," has yet to be demonstrated. In this study, we evaluated the direct impact of microbiota transplanted from epileptic animals to healthy recipient animals, to clarify whether the microbiota from animals with epilepsy can affect the excitability of the recipients' brain by lowering seizure thresholds. Our results provide the first evidence that mice who received microbiota from epileptic animals are more prone to develop status epilepticus, compared to recipients of "healthy" microbiota, after a subclinical dose of pilocarpine, indicating a higher susceptibility to seizures. The lower thresholds for seizure activity found in this study support the hypothesis that the microbiota, through the gut-brain axis, is able to affect neuronal excitability in the brain.

Therapeutic targeting of Lyn kinase to treat chorea-acanthocytosis.

Chorea-Acanthocytosis (ChAc) is a devastating, little understood, and currently untreatable neurodegenerative disease caused by VPS13A mutations. Based on our recent demonstration that accumulation of activated Lyn tyrosine kinase is a key pathophysiological event in human ChAc cells, we took advantage of Vps13a-/- mice, which phenocopied human ChAc. Using proteomic approach, we found accumulation of active Lyn, γ-synuclein and phospho-tau proteins in Vps13a-/- basal ganglia secondary to impaired autophagy leading to neuroinflammation. Mice double knockout Vps13a-/- Lyn-/- showed normalization of red cell morphology and improvement of autophagy in basal ganglia. We then in vivo tested pharmacologic inhibitors of Lyn: dasatinib and nilotinib. Dasatinib failed to cross the mouse brain blood barrier (BBB), but the more specific Lyn kinase inhibitor nilotinib, crosses the BBB. Nilotinib ameliorates both Vps13a-/- hematological and neurological phenotypes, improving autophagy and preventing neuroinflammation. Our data support the proposal to repurpose nilotinib as new therapeutic option for ChAc patients.

The Anti-Inflammatory Properties of Mesenchymal Stem Cells in Epilepsy: Possible Treatments and Future Perspectives.

Mesenchymal stem cells (MSCs) are multipotent adult cells with self-renewing capacities. MSCs display specific properties, such as the ability to repair damaged tissues, resulting in optimal candidates for cell therapy against degenerative diseases. In addition to the reparative functions of MSCs, growing evidence shows that these cells have potent immunomodulatory and anti-inflammatory properties. Therefore, MSCs are potential tools for treating inflammation-related neurological diseases, including epilepsy. In this regard, over the last decades, epilepsy has no longer been considered a purely neuronal pathology, since inflammatory events underlying the genesis of epilepsy have been demonstrated. This review assessed current knowledge on the use of MSCs in the treatment of epilepsy. Mostly, attention will be focused on the anti-inflammatory and immunological skills of MSCs. Understanding the mechanisms by which MSCs might modulate the severity of the disease will contribute to the development of new potential alternatives for both prophylaxis and treatment against epilepsy.

Ongoing Electroencephalographic Rhythms Related to Exploratory Movements in Transgenic TASTPM Mice.

BACKGROUND: The European PharmaCog study (http://www.pharmacog.org) has reported a reduction in delta (1-6 Hz) electroencephalographic (EEG) power (density) during cage exploration (active condition) compared with quiet wakefulness (passive condition) in PDAPP mice (hAPP Indiana V717F mutation) modeling Alzheimer's disease (AD) amyloidosis and cognitive deficits. OBJECTIVE: Here, we tested the reproducibility of that evidence in TASTPM mice (double mutation in APP KM670/671NL and PSEN1 M146V), which develop brain amyloidosis and cognitive deficits over aging. The reliability of that evidence was examined in four research centers of the PharmaCog study. METHODS: Ongoing EEG rhythms were recorded from a frontoparietal bipolar channel in 29 TASTPM and 58 matched "wild type" C57 mice (range of age: 12-24 months). Normalized EEG power was calculated. Frequency and amplitude of individual delta and theta frequency (IDF and ITF) peaks were considered during the passive and active conditions. RESULTS: Compared with the "wild type" group, the TASTPM group showed a significantly lower reduction in IDF power during the active over the passive condition (p < 0.05). This effect was observed in 3 out of 4 EEG recording units. CONCLUSION: TASTPM mice were characterized by "poor reactivity" of delta EEG rhythms during the cage exploration in line with previous evidence in PDAPP mice. The reliability of that result across the centers was moderate, thus unveiling pros and cons of multicenter preclinical EEG trials in TASTPM mice useful for planning future studies.

Impaired vocal communication, sleep-related discharges, and transient alteration of slow-wave sleep in developing mice lacking the GluN2A subunit of N-methyl-d-aspartate receptors.

OBJECTIVE: Glutamate-gated N-methyl-d-aspartate receptors (NMDARs) are instrumental to brain development and functioning. Defects in the GRIN2A gene, encoding the GluN2A subunit of NMDARs, cause slow-wave sleep (SWS)-related disorders of the epilepsy-aphasia spectrum (EAS). The as-yet poorly understood developmental sequence of early EAS-related phenotypes, and the role of GluN2A-containing NMDARs in the development of SWS and associated electroencephalographic (EEG) activity patterns, were investigated in Grin2a knockout (KO) mice. METHODS: Early social communication was investigated by ultrasonic vocalization (USV) recordings; the relationship of electrical activity of the cerebral cortex with SWS was studied using deep local field potential or chronic EEG recordings at various postnatal stages. RESULTS: Grin2a KO pups displayed altered USV and increased occurrence of high-voltage spindles. The pattern of slow-wave activity induced by low-dose isoflurane was altered in Grin2a KO mice in the 3rd postnatal week and at 1 month of age. These alterations included strong suppression of the delta oscillation power and an increase in the occurrence of the spike-wave bursts. The proportion of SWS and the sleep quality were transiently reduced in Grin2a KO mice aged 1 month but recovered by the age of 2 months. Grin2a KO mice also displayed spontaneous spike-wave discharges, which occurred nearly exclusively during SWS, at 1 and 2 months of age. SIGNIFICANCE: The impaired vocal communication, the spike-wave discharges occurring almost exclusively in SWS, and the age-dependent alteration of SWS that were all seen in Grin2a KO mice matched the sleep-related and age-dependent manifestations seen in children with EAS, hence validating the Grin2a KO as a reliable model of EAS disorders. Our data also show that GluN2A-containing NMDARs are involved in slow-wave activity, and that the period of postnatal brain development (postnatal day 30) when several anomalies peaked might be critical for GluN2A-dependent, sleep-related physiological and pathological processes.

The Original Histological Slides of Camillo Golgi and His Discoveries on Neuronal Structure.

The metallic impregnation invented by Camillo Golgi in 1873 has allowed the visualization of individual neurons in their entirety, leading to a breakthrough in the knowledge on the structure of the nervous system. Professor of Histology and of General Pathology, Golgi worked for decades at the University of Pavia, leading a very active laboratory. Unfortunately, most of Golgi's histological preparations are lost. The present contribution provides an account of the original slides on the nervous system from Golgi's laboratory available nowadays at the Golgi Museum and Historical Museum of the University of Pavia. Knowledge on the organization of the nervous tissue at the time of Golgi's observations is recalled. Notes on the equipment of Golgi's laboratory and the methodology Golgi used for his preparations are presented. Images of neurons from his slides (mostly from hippocampus, neocortex and cerebellum) are here shown for the first time together with some of Golgi's drawings. The sections are stained with the Golgi impregnation and Cajal stain. Golgi-impregnated sections are very thick (some more than 150 µm) and require continuous focusing during the microscopic observation. Heterogeneity of neuronal size and shape, free endings of distal dendritic arborizations, axonal branching stand out at the microscopic observation of Golgi-impregnated sections and in Golgi's drawings, and were novel findings at his time. Golgi also pointed out that the axon only originates from cell bodies, representing a constant and distinctive feature of nerve cells which distinguishes them from glia, and subserving transmission at a distance. Dendritic spines can be seen in some cortical neurons, although Golgi, possibly worried about artifacts, did not identify them. The puzzling intricacy of fully impregnated nervous tissue components offered to the first microscopic observations still elicit nowadays the emotion Golgi must have felt looking at his slides.

Alive and Ticking: Trypanosoma brucei Assaults the Circadian Clocks.

Rijo-Ferreira et al. report alterations of circadian rhythmicity at the behavioral, tissue, cellular, and molecular levels in mice after Trypanosoma brucei infection, showing that targeting cell clocks is a specific feature of these parasites. Thus, African trypanosomes cause a severe disease by disrupting time-keeping mechanisms and their synchrony.

Effects of n-3 polyunsaturated fatty acid supplementation on cognitive functions, electrocortical activity and neurogenesis in a non-human primate, the grey mouse lemur (Microcebus murinus).

Among environmental factors that may affect on brain function, some nutrients and particularly n-3 polyunsaturated fatty acids (n-3 PUFA) are required for optimal brain development. Their effects on cognitive functions, however, are still unclear, and studies in humans and rodents have yielded contradictory results. We used a non-human primate model, the grey mouse lemur, phylogenetically close to human. The aim of this study was to demonstrate the impact of n-3 PUFA supplementation on cognitive functions, neuronal activity and neurogenesis. Two groups of animals whose diet was supplemented with either fish oil (rich in n-3 PUFA) or olive oil as a control. These two groups were subjected to a visual discrimination task and to a test of anxiety in the open-field. In parallel, cortical activity was measured with telemetric ECoG recordings. Finally, adult neurogenesis was investigated ex vivo by means of immunohistochemistry. Animals supplemented with fish oil exhibited better visual discrimination performance and tended to have lower anxiety levels. Furthermore, supplementation increased the power of alpha, beta and gamma frequency bands in the EEG, which are related to various aspects of memory and decision-making. This study also provides the first evidence of the existence of adult neurogenesis process in a prosimian primate. Notably, lemurs supplemented with n-3 PUFAs for 21 months exhibited a higher number of newly born neurons in brain areas related to memory and emotions, compared to control animals. Altogether, these results point to long-term positive effects of dietary n-3 PUFAs on various functions of the primate brain. Further studies will be needed to determine a formal causal link between behavioral improvement and creation of new neurons.

Ongoing Electroencephalographic Activity Associated with Cortical Arousal in Transgenic PDAPP Mice (hAPP V717F).

BACKGROUND: It has been shown that theta (6-10 Hz) and delta (1-6 Hz) ongoing electroencephalographic (EEG) rhythms revealed variations in the cortical arousal in C57 Wild Type (WT) mice during cage exploration (active condition) compared to awake quiet behavior (passive condition; IMI PharmaCog project, www.pharmacog.eu). OBJECTIVE: The objective was to test if these EEG rhythms might be abnormal in old PDAPP mice modeling Alzheimer's disease (AD) with a hAPP Indiana V717F mutation (They show abnormal neural transmission, cognitive deficits, and brain accumulation of Aß1-42). METHODS: Ongoing EEG rhythms were recorded by a frontoparietal bipolar channel in 15 PDAPP and 23 WT C57 male mice (mean age of 22.8 months ±0.4 and 0.3 standard error, respectively). EEG absolute power (density) was calculated. Frequency and amplitude of individual delta and theta frequency (IDF and ITF) peaks were considered during passive and active states in the wakefulness. RESULTS: Compared with the WT group, the PDAPP group showed higher frequency of the IDF during the passive condition and lower frequency of the ITF during the active state. Furthermore, the WT but not PDAPP group showed significant changes in the frontoparietal EEG power (IDF, ITF) during active over passive state. CONCLUSION: PDAPP mice were characterized by less changes in the brain arousal during an active state as revealed by frontoparietal EEG rhythms. Future studies will have to cross-validate the present results on large animal groups, clarify the neurophysiological underpinning of the effect, and test if the disease modifying drugs against AD amyloidosis normalize those candiate EEG biomarkers in PDAPP mice.

All muscarinic acetylcholine receptors (M1-M5) are expressed in murine brain microvascular endothelium.

Clinical and experimental studies indicate that muscarinic acetylcholine receptors are potential pharmacological targets for the treatment of neurological diseases. Although these receptors have been described in human, bovine and rat cerebral microvascular tissue, a subtype functional characterization in mouse brain endothelium is lacking. Here, we show that all muscarinic acetylcholine receptors (M1-M5) are expressed in mouse brain microvascular endothelial cells. The mRNA expression of M2, M3, and M5 correlates with their respective protein abundance, but a mismatch exists for M1 and M4 mRNA versus protein levels. Acetylcholine activates calcium transients in brain endothelium via muscarinic, but not nicotinic, receptors. Moreover, although M1 and M3 are the most abundant receptors, only a small fraction of M1 is present in the plasma membrane and functions in ACh-induced Ca2+ signaling. Bioinformatic analyses performed on eukaryotic muscarinic receptors demonstrate a high degree of conservation of the orthosteric binding site and a great variability of the allosteric site. In line with previous studies, this result indicates muscarinic acetylcholine receptors as potential pharmacological targets in future translational studies. We argue that research on drug development should especially focus on the allosteric binding sites of the M1 and M3 receptors.

The excitatory/inhibitory input to orexin/hypocretin neuron soma undergoes day/night reorganization.

Orexin (OX)/hypocretin-containing neurons are main regulators of wakefulness stability, arousal, and energy homeostasis. Their activity varies in relation to the animal's behavioral state. We here tested whether such variation is subserved by synaptic plasticity phenomena in basal conditions. Mice were sacrificed during day or night, at times when sleep or wake, respectively, predominates, as assessed by electroencephalography in matched mice. Triple immunofluorescence was used to visualize OX-A perikarya and varicosities containing the vesicular glutamate transporter (VGluT)2 or the vesicular GABA transporter (VGAT) combined with synaptophysin (Syn) as a presynaptic marker. Appositions on OX-A+ somata were quantitatively analyzed in pairs of sections in epifluorescence and confocal microscopy. The combined total number of glutamatergic (Syn+/VGluT2+) and GABAergic (Syn+/VGAT+) varicosities apposed to OX-A somata was similar during day and night. However, glutamatergic varicosities were significantly more numerous at night, whereas GABAergic varicosities prevailed in the day. Triple immunofluorescence in confocal microscopy was employed to visualize synapse scaffold proteins as postsynaptic markers and confirmed the nighttime prevalence of VGluT2+ together with postsynaptic density protein 95+ excitatory contacts, and daytime prevalence of VGAT+ together with gephyrin+ inhibitory contacts, while also showing that they formed synapses on OX-A+ cell bodies. The findings reveal a daily reorganization of axosomatic synapses in orexinergic neurons, with a switch from a prevalence of excitatory innervation at a time corresponding to wakefulness to a prevalence of inhibitory innervations in the antiphase, at a time corresponding to sleep. This reorganization could represent a key mechanism of plasticity of the orexinergic network in basal conditions.

Nonsteroidal anti-inflammatory drugs in clinical and experimental epilepsy.

Current antiepileptic drugs have limited efficacy and provide little or no benefits in 30% of the patients. Given that a role for brain inflammation in epilepsy has been repeatedly reported in recent years, the potential of anti-inflammatory drugs should be explored in depth, as they may provide new therapeutical approaches in preventing or reducing epileptogenesis. Here, we review preclinical (both in vivo and in vitro) and clinical epilepsy studies in which nonsteroidal antiinflammatory drugs (NSAIDs), i.e. cyclooxygenase-2 (COX-2) selective inhibitors (COXIBs) and nonselective NSAIDs, were used for seizure control. The effects of NSAIDs are reviewed in animal models of both chemical (pilocarpine, kainic acid, pentylenetetrazol, or carbachol administration) and electrical (tetanic hippocampal stimulation, electroshock) seizure induction. In the pilocarpine model, NSAIDs are neuroprotective, reduce mossy fiber sprouting or diminish P-glycoprotein upregulation, but only rarely protect against seizures. While neuroprotective effects have also been observed in the kainic acid model, NSAIDs tend in general to worsen seizure activity. Effects of COXIB administration in the pentylenetetrazol-induced seizures model are variable, alternating from protection against seizures to null effects or even increased incidence of convulsions. Moreover, NSAIDs tested in the tetanic hippocampal stimulation model diminished the seizure-associated P-glycoprotein upregulation, but were not very effective in seizure control. NSAIDs efficacy in experimental in vivo epilepsy studies may be influenced by multiple factors, including the timing of administration (before or after status epilepticus induction), the animal model of epilepsy or some of the signaling pathways involved in cyclooxygenase induction (e.g. prostaglandins and their receptors). On the other hand, the few clinical studies on the use of NSAIDs in neurological pathologies accompanied/characterized by seizures indicate that nonselective NSAIDs (e.g. aspirin) in prolonged, low-dose treatments may offer protection against seizures and stroke-like events. No clinical trials in epileptic patients using COXIBs have been conducted so far, as several international drug-control authorities have withdrawn these drugs from the market; future studies should focus on improved COXIB formulations. We argue that, while the available evidence is still inconclusive, the potential therapeutic benefits of controlling and diminishing brain inflammation in the treatment of epilepsy should be actively explored.

On-going electroencephalographic rhythms related to cortical arousal in wild-type mice: the effect of aging.

Resting state electroencephalographic (EEG) rhythms reflect the fluctuation of cortical arousal and vigilance in a typical clinical setting, namely the EEG recording for few minutes with eyes closed (i.e., passive condition) and eyes open (i.e., active condition). Can this procedure be back-translated to C57 (wild type) mice for aging studies? On-going EEG rhythms were recorded from a frontoparietal bipolar channel in 85 (19 females) C57 mice. Male mice were subdivided into 3 groups: 25 young (4.5-6 months), 18 middle-aged (12-15 months), and 23 old (20-24 months) mice to test the effect of aging. EEG power density was compared between short periods (about 5 minutes) of awake quiet behavior (passive) and dynamic exploration of the cage (active). Compared with the passive condition, the active condition induced decreased EEG power at 1-2 Hz and increased EEG power at 6-10 Hz in the group of 85 mice. Concerning the aging effects, the passive condition showed higher EEG power at 1-2 Hz in the old group than that in the others. Furthermore, the active condition exhibited a maximum EEG power at 6-8 Hz in the former group and 8-10 Hz in the latter. In the present conditions, delta and theta EEG rhythms reflected changes in cortical arousal and vigilance in freely behaving C57 mice across aging. These changes resemble the so-called slowing of resting state EEG rhythms observed in humans across physiological and pathological aging. The present EEG procedures may be used to enhance preclinical phases of drug discovery in mice for understanding the neurophysiological effects of new compounds against brain aging.

H1N1 influenza virus induces narcolepsy-like sleep disruption and targets sleep-wake regulatory neurons in mice.

An increased incidence in the sleep-disorder narcolepsy has been associated with the 2009-2010 pandemic of H1N1 influenza virus in China and with mass vaccination campaigns against influenza during the pandemic in Finland and Sweden. Pathogenetic mechanisms of narcolepsy have so far mainly focused on autoimmunity. We here tested an alternative working hypothesis involving a direct role of influenza virus infection in the pathogenesis of narcolepsy in susceptible subjects. We show that infection with H1N1 influenza virus in mice that lack B and T cells (Recombinant activating gene 1-deficient mice) can lead to narcoleptic-like sleep-wake fragmentation and sleep structure alterations. Interestingly, the infection targeted brainstem and hypothalamic neurons, including orexin/hypocretin-producing neurons that regulate sleep-wake stability and are affected in narcolepsy. Because changes occurred in the absence of adaptive autoimmune responses, the findings show that brain infections with H1N1 virus have the potential to cause per se narcoleptic-like sleep disruption.

Are they in or out? The elusive interaction between Qtracker ® 800 vascular labels and brain endothelial cells.

AIM: Qtracker(®)800 Vascular labels (Qtracker(®)800) are promising biomedical tools for high-resolution vasculature imaging; their effects on mouse and human endothelia, however, are still unknown. MATERIALS & METHODS: Qtracker(®)800 were injected in Balb/c mice, and brain endothelium uptake was investigated by transmission electron microscopy 3-h post injection. We then investigated, in vitro, the effects of Qtracker(®)800 exposure on mouse and human endothelial cells by calcium imaging. RESULTS: Transmission electron microscopy images showed nanoparticle accumulation in mouse brain endothelia. A subset of mouse and human endothelial cells generated intracellular calcium transients in response to Qtracker(®)800. CONCLUSION: Qtracker(®)800 nanoparticles elicit endothelial functional responses, which prompts biomedical safety evaluations and may bias the interpretation of experimental studies involving vascular imaging.

Antidepressant activity of fingolimod in mice.

Recent findings indicate that fingolimod, the first oral drug approved for the treatment of multiple sclerosis (MS), acts as a direct inhibitor of histone deacetylases (HDACs) and enhances the production of brain-derived neurotrophic factor (BDNF) in the CNS. Both mechanisms are relevant to the pathophysiology and treatment of major depression. We examined the antidepressant activity of fingolimod in mice subjected to chronic unpredictable stress (CUS), a model of reactive depression endowed with face and pharmacological validity. Chronic treatment with fingolimod (3 mg kg(-1), i.p., once a day for 4 weeks) reduced the immobility time in the forced swim test (FST) in a large proportion of CUS mice. This treatment also caused anxiogenic-like effects in the social interaction test without affecting anxiety-like behavior in the elevated plus maze or spatial learning in the water maze. CUS mice showed reduced BDNF levels and enhanced HDAC2 levels in the hippocampus. These changes were reversed by fingolimod exclusively in mice that showed a behavioral response to the drug in the FST. Fingolimod treatment also enhanced H3 histone K14-acetylation and adult neurogenesis in the hippocampus of CUS mice. Fingolimod did not affect most of the parameters we have tested in unstressed control mice. The antidepressant-like activity of fingolimod was confirmed in mice chronically treated with corticosterone. These findings show for the first time that fingolimod exerts antidepressant-like effect acting in a "disease-dependent" manner, and raise the interesting possibility that the drug could relieve depressive symptoms in MS patients independently of its disease-modifying effect on MS.

New players in the neurovascular unit: insights from experimental and clinical epilepsy.

The conventional notion that neurons are exclusively responsible for brain signaling is increasingly challenged by the idea that brain function in fact depends on a complex interplay between neurons, glial cells, vascular endothelium, and immune-related blood cells. Recent data demonstrates that neuronal activity is profoundly affected by an entire cellular and extracellular 'orchestra', the so-called neurovascular unit (NVU). Among the 'musical instruments' of this orchestra, there may be molecules long-known in biomedicine as important mediators of inflammatory and immune responses in the organism, as well as non-neuronal cells, e.g., leukocytes. We here review recent evidence on the structure and function of the NVU, both in the healthy brain and in pathological conditions, such as the abnormal NVU activation observed in epilepsy. We will argue that a better understanding of NVU function will require the addition of new players to the 'orchestra'.