Calcium Signaling in Astrocytes

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DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (15): Translational Science and specific Challenge Topic, 15- NS-104: Early-Stage Therapy Development. The major goal of the proposed work is to develop novel technical and theoretical means to understand the mechanisms underlying temporal lobe epilepsy (TLE) and to assess new classes of possible treatments for this devastating disorder. TLE is often difficult to treat using currently available approaches and entails an economic cost of $12 billion dollars per year within the United States alone. The proposed work is transformative on several fronts. First, the work focuses on the putative role of glial support cells (specifically, astrocytes) in TLE. Although there is a convincing body of evidence that astrocytes are involved in epileptic dysfunction, this evidence has not yet gained wide acceptance, leaving approaches that focus on astrocytes underappreciated and underutilized. Second, the proposed approach depends on a novel imaging technique, called targeted path scanning (TPS), which allows recordings of neuronal and glial calcium transients in up to 100 cells simultaneously, with single-cell spatial resolution and excellent temporal resolution. The TPS approach allows the proposed research program to study mechanisms and putative treatments of TLE in interacting neuronal and glial networks, with spatiotemporal resolution that permits simultaneous analysis at both the cellular and network levels. The proposed study has two specific aims. Aim 1 addresses whether the properties of astrocytic population calcium transients are altered in brain slices derived from animals that have been subjected to the kainic acid (KA) model of TLE. These transients will be characterized, and compared with data from age-matched controls, in slices from animals during both the latent period (after induction of status epilepticus but before spontaneous seizures) and after spontaneous seizures have begun. Relevant properties to be studied include temporal frequency, magnitude, and spatial extent throughout the astrocytic network. Aim 2 focuses on interactions between astrocytic calcium transients and spike-driven calcium transients in nearby neurons. Specific questions to be addressed in this aim include: Are calcium transients in astrocytes and neurons spatially and/or temporally correlated? If so, which cell type in a given area leads the other? How do known anti-epileptic drugs affect calcium transients in astrocytes, calcium transients in neurons, and the potential interactions between the two cell types? Finally, can this ground-breaking technology be used as a network- based assay for the identification of novel anticonvulsant molecules for the treatment of pharmacoresistant epilepsy? The proposed project-a pioneering effort between a pharmacologist/epileptologist and a bioengineer-is translational in its focus and intent. The major goal of the proposed work is to develop new theories and approaches that could be invaluable in discovering new pharmacological treatments for the devastating seizure disorder, temporal lobe epilepsy. PUBLIC HEALTH RELEVANCE: Temporal lobe epilepsy is a seizure disorder with devastating effects, particularly in the large number of patients for whom current treatments are ineffective. The purpose of the proposed work is to use ground- breaking imaging technology to study this disease in interacting networks of both nerve cells and glial metabolic support cells. A likely outcome of the proposed work will be entirely new ways to assess potential pharmacological therapies for epilepsy.