Astrocyte-Specific Disruption of SynCAM1 Signaling Results in ADHD-Like Behavioral Manifestations

SynCAM1 is an adhesion molecule involved in synaptic differentiation and organization. SynCAM1 is also expressed in astroglial cells where it mediates astrocyte-to astrocyte and glial-neuronal adhesive communication. In astrocytes, SynCAM1 is functionally linked to erbB4 receptors, which are involved in the control of both neuronal/glial development and mature neuronal and glial function. Here we report that mice carrying a dominant-negative form of SynCAM1 specifically targeted to astrocytes (termed GFAP-DNSynCAM1 mice) exhibit disrupted diurnal locomotor activity with enhanced and more frequent episodes of activity than control littermates during the day (when the animals are normally sleeping) accompanied by shorter periods of rest. GFAP-DNSynCAM1 mice also display high levels of basal activity in the dark period (the rodent's awake/active time) that are attenuated by the psychostimulant D,L-amphetamine, and reduced anxiety levels in response to both avoidable and unavoidable provoking stimuli. These results indicate that disruption of SynCAM1-dependent astroglial function results in behavioral abnormalities similar to those described in animals model of attention-deficit hyperactive disorder (ADHD), and suggest a hitherto unappreciated contribution of glial cells to the pathophysiology of this disorder

Homeostatic control of brain function – new approaches to understand epileptogenesis

Neuronal excitability of the brain and ongoing homeostasis depend not only on intrinsic neuronal properties, but also on external environmental factors; together these determine the functionality of neuronal networks. Homeostatic factors become critically important during epileptogenesis, a process that involves complex disruption of self-regulatory mechanisms. Here we focus on the bioenergetic homeostatic network regulator adenosine, a purine nucleoside whose availability is largely regulated by astrocytes. Endogenous adenosine modulates complex network function through multiple mechanisms including adenosine receptor-mediated pathways, mitochondrial bioenergetics, and adenosine receptor-independent changes to the epigenome. Accumulating evidence from our laboratories shows that disruption of adenosine homeostasis plays a major role in epileptogenesis. Conversely, we have found that reconstruction of adenosine’s homeostatic functions provides new hope for the prevention of epileptogenesis. We will discuss how adenosine-based therapeutic approaches may interfere with epileptogenesis on an epigenetic level, and how dietary interventions can be used to restore network homeostasis in the brain. We conclude that reconstruction of homeostatic functions in the brain offers a new conceptual advance for the treatment of neurological conditions which goes far beyond current target-centric treatment approaches

Ketogenic Diet Improves Core Symptoms of Autism in BTBR Mice

Autism spectrum disorders share three core symptoms: impaired sociability, repetitive behaviors and communication deficits. Incidence is rising, and current treatments are inadequate. Seizures are a common comorbidity, and since the 1920’s a high-fat, low-carbohydrate ketogenic diet has been used to treat epilepsy. Evidence suggests the ketogenic diet and analogous metabolic approaches may benefit diverse neurological disorders. Here we show that a ketogenic diet improves autistic behaviors in the BTBR mouse. Juvenile BTBR mice were fed standard or ketogenic diet for three weeks and tested for sociability, self-directed repetitive behavior, and communication. In separate experiments, spontaneous intrahippocampal EEGs and tests of seizure susceptibility (6 Hz corneal stimulation, flurothyl, SKF83822, pentylenetetrazole) were compared between BTBR and control (C57Bl/6) mice. Ketogenic diet-fed BTBR mice showed increased sociability in a three-chamber test, decreased self-directed repetitive behavior, and improved social communication of a food preference. Although seizures are a common comorbidity with autism, BTBR mice fed a standard diet exhibit neither spontaneous seizures nor abnormal EEG, and have increased seizure susceptibility in just one of four tests. Thus, behavioral improvements are dissociable from any antiseizure effect. Our results suggest that a ketogenic diet improves multiple autistic behaviors in the BTBR mouse model. Therefore, ketogenic diets or analogous metabolic strategies may offer novel opportunities to improve core behavioral symptoms of autism spectrum disorders

A Ketogenic Diet Suppresses Seizures in Mice through Adenosine A1 Receptors

A ketogenic diet (KD) is a high-fat, low-carbohydrate metabolic regimen; its effectiveness in the treatment of refractory epilepsy suggests that the mechanisms underlying its anticonvulsive effects differ from those targeted by conventional antiepileptic drugs. Recently, KD and analogous metabolic strategies have shown therapeutic promise in other neurologic disorders, such as reducing brain injury, pain, and inflammation. Here, we have shown that KD can reduce seizures in mice by increasing activation of adenosine A1 receptors (A1Rs). When transgenic mice with spontaneous seizures caused by deficiency in adenosine metabolism or signaling were fed KD, seizures were nearly abolished if mice had intact A1Rs, were reduced if mice expressed reduced A1Rs, and were unaltered if mice lacked A1Rs. Seizures were restored by injecting either glucose (metabolic reversal) or an A1R antagonist (pharmacologic reversal). Western blot analysis demonstrated that the KD reduced adenosine kinase, the major adenosine-metabolizing enzyme. Importantly, hippocampal tissue resected from patients with medically intractable epilepsy demonstrated increased adenosine kinase. We therefore conclude that adenosine deficiency may be relevant to human epilepsy and that KD can reduce seizures by increasing A1R-mediated inhibition

Recommendations for reproducibility of cerebrospinal fluid extracellular vesicle studies

Cerebrospinal fluid (CSF) is a clear, transparent fluid derived from blood plasma that protects the brain and spinal cord against mechanical shock, provides buoyancy, clears metabolic waste and transports extracellular components to remote sites in the brain. Given its contact with the brain and the spinal cord, CSF is the most informative biofluid for studies of the central nervous system (CNS). In addition to other components, CSF contains extracellular vesicles (EVs) that carry bioactive cargoes (e.g., lipids, nucleic acids, proteins), and that can have biological functions within and beyond the CNS. Thus, CSF EVs likely serve as both mediators of and contributors to communication in the CNS. Accordingly, their potential as biomarkers for CNS diseases has stimulated much excitement for and attention to CSF EV research. However, studies on CSF EVs present unique challenges relative to EV studies in other biofluids, including the invasive nature of CSF collection, limited CSF volumes and the low numbers of EVs in CSF as compared to plasma. Here, the objectives of the International Society for Extracellular Vesicles CSF Task Force are to promote the reproducibility of CSF EV studies by providing current reporting and best practices, and recommendations and reporting guidelines, for CSF EV studies. To accomplish this, we created and distributed a world‐wide survey to ISEV members to assess methods considered ‘best practices’ for CSF EVs, then performed a detailed literature review for CSF EV publications that was used to curate methods and resources. Based on responses to the survey and curated information from publications, the CSF Task Force herein provides recommendations and reporting guidelines to promote the reproducibility of CSF EV studies in seven domains: (i) CSF Collection, Processing, and Storage; (ii) CSF EV Separation/Concentration; (iii) CSF EV Size and Number Measurements; (iv) CSF EV Protein Studies; (v) CSF EV RNA Studies; (vi) CSF EV Omics Studies and (vii) CSF EV Functional Studies

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

© 2024 The Authors. Journal of Extracellular Vesicles, published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.Peer reviewe

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its ‘Minimal Information for Studies of Extracellular Vesicles’, which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Glial adenosine kinase--a neuropathological marker of the epileptic brain

Experimental research over the past decade has supported the critical role of astrocytes activated by different types of injury and the pathophysiological processes that underlie the development of epilepsy. In both experimental and human epileptic tissues astrocytes undergo complex changes in their physiological properties, which can alter glio-neuronal communication, contributing to seizure precipitation and recurrence. In this context, understanding which of the molecular mechanisms are crucially involved in the regulation of glio-neuronal interactions under pathological conditions associated with seizure development is important to get more insight into the role of astrocytes in epilepsy. This article reviews current knowledge regarding the role of glial adenosine kinase as a neuropathological marker of the epileptic brain. Both experimental findings in clinically relevant models, as well as observations in drug-resistant human epilepsies will be discussed, highlighting the link between astrogliosis, dysfunction of adenosine homeostasis and seizure generation and therefore suggesting new strategies for targeting astrocyte-mediated epileptogenesi

Regulation of Sarco/Endoplasmic Reticulum Ca2+ ATPase mRNA as a mechanism to prevent Ca2+ cytotoxicity

The Sarco/Endoplasmic Reticulum Ca2+-ATPase Pump (serca2) plays a critical role in intracellular Ca2+ dynamics. One function is to store intracellular Ca2+ in the endoplasmic reticulum. By sequestering Ca2+ from the cytoplasm, serca pumps can act to prevent Ca2+ induced excitotoxicity. Recent studies have shown that androgens can also prevent excitotoxic cell death. Therefore, in this study, we investigated if androgens can regulate serca2. Primary hippocampal neurons were prepared from E18 rat fetuses and after 14 days in vitro, were treated with either dihydrotestosterone (DHT) or vehicle (control) for 48 hours. Following treatment, cells were harvested, total RNA was isolated, and serca2 mRNA was measured using quantitative real time RT-PCR. GAPDH mRNA was measured as an internal control. Levels of serca2 mRNA were compared between the two treatment groups. A dose response curve for DHT was generated (1nM and 10nM). A 1nM concentration of DHT significantly upregulated serca2 mRNA as opposed to that of 10nM where a down-regulation was seen. The upregulation of serca2 mRNA following DHT treatment could be responsible for the neuroprotective actions attributed to androgen receptors.High Honors