Abstracts

Rationale: Micro-electrode arrays (MEAs) have been widely utilized to measure neuronal activities in vitro.  The MEA technology offers many unique advantages to investigate neuronal circuitry, interaction and models of learning and memory, development, aging, disease and neurotoxicity.  While several high-throughput platforms have been utilized for drug screening with cultured cell applications in recent years, there have been limited platforms designed for acute and culture slice applications. Here we present the capabilities of the MED64-Quad II system, a novel medium-throughput MEA designed specifically for acute or cultured slice applications.  Methods: Recordings were made from acute hippocampal slices from 6-8 week old male ICR strain mice and the extracellular signals were obtained at 16 electrodes per slice (4 slices recorded simultaneously) or 64 electrodes per slice with MED64-basic system.  Spontaneous spikes were recorded with 4 slices simultaneously using the MED64-Quad II System.  On a given experiment of 16 or 64 electrodes recording, spontaneous firing were recorded from hippocampal and entorhinal cortex.  The firing frequency per channel and the number of synchronized bursts were analyzed.  Pharmacological agents NMDA, bicuculline, AP5, PTZ (pentylenetetrazole), VPA (sodium valproate), and Phenytoin were tested on the slices using MED64 system. Results: Synchronized burst firing, a hallmark of epilepsy, was observed following bath perfusion of 10 µM NMDA (n=7, p < 0.01), 10 µM bicuculline (n=7, p < 0.01) and 5 mM PTZ (n=14, p < 0.01). PTZ-induced synchronizing bursting activities were reversed in 100% of slices tested by 5 mM VPA (n=7, p < 0.01) or 100 µM Phenytoin (n=7, p < 0.01). NMDA-induced synchronized bursting was inhibited in all slices tested by application of 50 µM AP5 (n=7, p < 0.01). Due to the higher throughput of the MED64-Quad II System, the results from these experiments were obtained much more quickly than with traditional slice recordings; 1 day was needed for each experimental group. Conclusions: The results of this study indicated that the MED64-Quad II and Basic system increases throughput while maintaining high-sensitivity to detect spontaneous spiking signals.  It is a useful tool for drug discovery, target validation, compound screening for antiepileptic drug targets and pharmacological studies in acute brain slice applications in vitro and enables greatly reduced experimental time. Funding: This work was supported by Alpha MED Scientific, Inc.