title: Zebrafish needle EMG: a new tool for high-throughput drug screens.
abstract: Zebrafish models have recently been highlighted as a valuable tool in studying the molecular basis of neuromuscular diseases and developing new pharmacological treatments. Needle electromyography (EMG) is needed not only for validating transgenic zebrafish models with muscular dystrophies (MD), but also for assessing the efficacy of therapeutics. However, performing needle EMG on larval zebrafish has not been feasible due to the lack of proper EMG sensors and systems for such small animals. We introduce a new type of EMG needle electrode to measure intramuscular activities of larval zebrafish, together with a method to hold the animal in position during EMG, without anesthetization. The silicon-based needle electrode was found to be sufficiently strong and sharp to penetrate the skin and muscles of zebrafish larvae, and its shape and performance did not change after multiple insertions. With the use of the proposed needle electrode and measurement system, EMG was successfully performed on zebrafish at 30 days postfertilization (dpf) and at 5 dpf. Burst patterns and spike morphology of the recorded EMG signals were analyzed. The measured single spikes were triphasic with an initial positive deflection, which is typical for motor unit action potentials, with durations of ∼10 ms, whereas the muscle activity was silent during the anesthetized condition. These findings confirmed the capability of this system of detecting EMG signals from very small animals such as 5 dpf zebrafish. The developed EMG sensor and system are expected to become a helpful tool in validating zebrafish MD models and further developing therapeutics.
authors.affiliation: Department of Medical System Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea;
authors.forename: Sung-Joon
authors.initials: SJ
authors.lastname: Cho
authors.affiliation: Department of Neurology, Chonnam National University Medical School, Gwangju, Korea;
authors.forename: Tai-Seung
authors.initials: TS
authors.lastname: Nam
authors.affiliation: School of Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea; and.
authors.forename: Donghak
authors.initials: D
authors.lastname: Byun
authors.affiliation: Department of Biomedical Sciences, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Seok-Yong
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Department of Neurology, Chonnam National University Medical School, Gwangju, Korea;
authors.forename: Myeong-Kyu
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Department of Medical System Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea; School of Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Korea; and soheekim@gist.ac.kr.
authors.forename: Sohee
authors.initials: S
authors.lastname: Kim
mesh_terms: D000200:Action Potentials; D000818:Animals; D055808:Drug Discovery / Q000379:methods; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D057166:High-Throughput Screening Assays / Q000295:instrumentation / Q000379:methods*; D018482:Muscle, Skeletal / Q000502:physiology; D015027:Zebrafish
keywords: electrode; microneedle; motor unit action potential; needle electromyography; zebrafish