Zebrafish Larvae's Response to Electricity is Mediated by Dopaminergic
Agonists and Antagonists
Abstract
The signaling molecular mechanisms in zebrafish response to electricity
are unknown, so here we asked if changes to dopaminergic signaling
pathways can affect their electrically-evoked locomotion. To answer this
question, the effects of multiple selective and non-selective dopamine
compounds on the electric response of zebrafish larvae is investigated.
A microfluidic device with enhanced control of experimentation with
multiple larvae is used, which features a novel design to immobilize
four zebrafish larvae in parallel and expose them to electric current
that induces tail locomotion. In 6 days post-fertilization zebrafish
larvae, the electric induced locomotor response is quantified in terms
of the tail movement duration and beating frequency to discern the
effect of non-lethal concentrations of dopaminergic agonists
(apomorphine, SKF-81297, and quinpirole), and antagonists (butaclamol,
SCH-23390, and haloperidol). All dopamine antagonists decrease locomotor
activity, while dopamine agonists do not induce similar behaviours in
larvae. The D2- like selective dopamine agonist quinpirole enhances
movement. However, exposure to non-selective and D1-selective dopamine
agonists apomorphine and SKF-81297 cause no significant change in the
electric response. Exposing larvae that were pre-treated with butaclamol
and haloperidol to apomorphine and quinpirole, respectively, restores
electric locomotion. The results demonstrate a correlation between
electric response and the dopamine signalling pathway. We propose that
the electrofluidic assay has profound application potential as a
chemical screening method when investigating biological pathways,
behaviors, and brain disorders.