Person: Staley, Kevin
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Staley
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Kevin
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Staley, Kevin
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Publication Developmental Decrease of Neuronal Chloride Concentration Is Independent of Trauma in Thalamocortical Brain Slices(Public Library of Science, 2016) Glykys, Joseph; Staley, KevinThe intraneuronal chloride concentration ([Cl-]i) is paramount for determining the polarity of signaling at GABAA synapses in the central nervous system. Sectioning hippocampal brain slices increases [Cl-]i in the superficial layers. It is not known whether cutting trauma also increases [Cl-]i in the neocortex and thalamus, and whether the effects of trauma change during development. We used Cl- imaging to study the [Cl-]i vs. the distance from the cut surface in acute thalamocortical slices from mice at developmental ages ranging from post-natal day 5 (P5) to P20. We demonstrate: 1) [Cl-]i is higher in the most superficial areas in both neocortical and thalamic brain slices at all ages tested and, 2) there is a developmental decrease in [Cl-]i that is independent of acute trauma caused by brain slicing. We conclude that [Cl-]i has a developmental progression during P5-20 in both the neocortex and thalamus. However, in both brain regions and during development the neurons closest to the slicing trauma have an elevated [Cl-]i.Publication Diazepam effect during early neonatal development correlates with neuronal Cl−(John Wiley and Sons Inc., 2015) Glykys, Joseph; Staley, KevinAbstract Objective: Although benzodiazepines and other GABAA receptors allosteric modulators are used to treat neonatal seizures, their efficacy may derive from actions on subcortical structures. Side effects of benzodiazepines in nonseizing human neonates include myoclonus, seizures, and abnormal movements. Excitatory actions of GABA may underlie both side effects and reduced anticonvulsant activity of benzodiazepines. Neocortical organotypic slice cultures were used to study: (1) spontaneous cortical epileptiform activity during early development; (2) developmental changes in [Cl−]i and (3) whether diazepam's anticonvulsant effect correlated with neuronal [Cl−]i. Methods: Epileptiform activity in neocortical organotypic slice cultures was measured by field potential recordings. Cl− changes during development were assessed by multiphoton imaging of neurons transgenically expressing a Cl‐sensitive fluorophore. Clinically relevant concentrations of diazepam were used to test the anticonvulsant effectiveness at ages corresponding to premature neonates through early infancy. Results: (1) Neocortical organotypic slices at days in vitro 5 (DIV5) exhibited spontaneous epileptiform activity. (2) Epileptiform event duration decreased with age. (3) There was a progressive decrease in [Cl−]i over the same age range. (4) Diazepam was ineffective in decreasing epileptiform activity at DIV5‐6, but progressively more effective at older ages through DIV15. (5) At DIV5‐6, diazepam worsened epileptiform activity in 50% of the slices. Interpretation The neocortical organotypic slice is a useful model to study spontaneous epileptiform activity. Decreasing [Cl−]i during development correlates with decreasing duration of spontaneous epileptiform activity and increasing anticonvulsant efficacy of diazepam. We provide a potential explanation for the reports of seizures and myoclonus induction by benzodiazepines in newborn human neonates and the limited electrographic efficacy of benzodiazepines for the treatment of neonatal seizures.Publication What Elements of the Inflammatory System Are Necessary for Epileptogenesis In Vitro?1,2(Society for Neuroscience, 2015) Park, Kyung-Il; Dzhala, Volodymyr; Saponjian, Yero; Staley, KevinAbstract Epileptogenesis in vivo can be altered by manipulation of molecules such as cytokines and complement that subserve intercellular signaling in both the inflammatory and central nervous systems. Because of the dual roles of these signaling molecules, it has been difficult to precisely define the role of systemic inflammation in epileptogenesis. Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy. However, this preparation still retains key cellular inflammatory mediators. Here, we found that rodent hippocampal organotypic slice cultures depleted of T lymphocytes and microglia developed epileptic activity at essentially the same rate and to similar degrees of severity as matched control slice cultures. These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.Publication Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition(Public Library of Science, 2017) Liu, Jing; Saponjian, Yero; Mahoney, Mark M.; Staley, Kevin; Berdichevsky, YevgenyRodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium), which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF). Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH) levels (biomarkers of ictal activity and cell death, respectively) in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy.Publication Staged anticonvulsant screening for chronic epilepsy(John Wiley and Sons Inc., 2016) Berdichevsky, Yevgeny; Saponjian, Yero; Park, Kyung‐Il; Roach, Bonnie; Pouliot, Wendy; Lu, Kimberly; Swiercz, Waldemar; Dudek, F. Edward; Staley, KevinAbstract Objective: Current anticonvulsant screening programs are based on seizures evoked in normal animals. One‐third of epileptic patients do not respond to the anticonvulsants discovered with these models. We evaluated a tiered program based on chronic epilepsy and spontaneous seizures, with compounds advancing from high‐throughput in vitro models to low‐throughput in vivo models. Methods: Epileptogenesis in organotypic hippocampal slice cultures was quantified by lactate production and lactate dehydrogenase release into culture media as rapid assays for seizure‐like activity and cell death, respectively. Compounds that reduced these biochemical measures were retested with in vitro electrophysiological confirmation (i.e., second stage). The third stage involved crossover testing in the kainate model of chronic epilepsy, with blinded analysis of spontaneous seizures after continuous electrographic recordings. Results: We screened 407 compound‐concentration combinations. The cyclooxygenase inhibitor, celecoxib, had no effect on seizures evoked in normal brain tissue but demonstrated robust antiseizure activity in all tested models of chronic epilepsy. Interpretation The use of organotypic hippocampal cultures, where epileptogenesis occurs on a compressed time scale, and where seizure‐like activity and seizure‐induced cell death can be easily quantified with biomarker assays, allowed us to circumvent the throughput limitations of in vivo chronic epilepsy models. Ability to rapidly screen compounds in a chronic model of epilepsy allowed us to find an anticonvulsant that would be missed by screening in acute models.Publication Neuroprotective levels of IGF-1 exacerbate epileptogenesis after brain injury(Nature Publishing Group, 2016) Song, Yu; Pimentel, Corrin; Walters, Katherine; Boller, Lauren; Ghiasvand, Shabnam; Liu, Jing; Staley, Kevin; Berdichevsky, YevgenyExogenous Insulin-Like Growth Factor-1 (IGF-1) is neuroprotective in animal models of brain injury, and has been considered as a potential therapeutic. Akt-mTOR and MAPK are downstream targets of IGF-1 signaling that are activated after brain injury. However, both brain injury and mTOR are linked to epilepsy, raising the possibility that IGF-1 may be epileptogenic. Here, we considered the role of IGF-1 in development of epilepsy after brain injury, using the organotypic hippocampal culture model of post-traumatic epileptogenesis. We found that IGF-1 was neuroprotective within a few days of injury but that long-term IGF-1 treatment was pro-epileptic. Pro-epileptic effects of IGF-1 were mediated by Akt-mTOR signaling. We also found that IGF-1 – mediated increase in epileptic activity led to neurotoxicity. The dualistic nature of effects of IGF-1 treatment demonstrates that anabolic enhancement through IGF-1 activation of mTOR cascade can be beneficial or harmful depending on the stage of the disease. Our findings suggest that epilepsy risk may need to be considered in the design of neuroprotective treatments for brain injury.