Nonclinical human neural new approach methodologies (NAMs): Electrophysiological assessment of opioid agonist and antagonist combination

Background and Purpose
New approach methodologies (NAMs) including microphysiological systems in combination with human induced pluripotent stem cell (hiPSC)-derived neural cells and multielectrode array (MEA) have demonstrated utility for evaluating electrophysiological effects of CNS active compounds including those with potential seizurogenic liability. Here, we extend a neural NAM assay to assessment of an opioid agonist and reversal agent.
Methods
An in vitro human NAM composed of hiPSC-neurons and hiPSC-astrocytes coupled with MEA platform was used to assess spontaneous neural electrophysiology. Neural cells were cultured on MEA plates then treated with varying concentrations of the µ-opioid receptor agonist DAMGO (D-Ala(2)-mephe(4)-gly-ol(5))enkephalin). Following DAMGO treatment, the opioid antagonist naloxone [10 µM] was added to each well to evaluate phenotypic reversal.
Results
The opioid agonist DAMGO modulated neural electrophysiological activity in a concentration-dependent manner relative to vehicle control. These changes were observed across neural parameters relating to overall neural activity, single electrode burst, network burst, and synchronicity. These effects were reversed by the opioid antagonist naloxone. Moreover, DAMGO treatment disrupted higher order baseline neural patterns. Finally, subpopulation analysis revealed divergent opioid-induced higher order network response influenced by baseline network activity.
Conclusions
These findings demonstrate the hiPSC neural NAM can characterize human network electrical activity at baseline and following exposure to an opioid agonist and antagonist pair. Future studies will investigate additional opioids and reversal agents, as well as other MEA metrics and activity patterns that may best describe concentration- and time-dependent changes in neural activity.