A microfluidic device to study electrotaxis and dopaminergic system of zebrafish larvae

Abstract

The zebrafish is a lower vertebrate model organism offering multiple applications for both fundamental and biomedical research into the nervous system from genes to behaviour. Investigation of zebrafish larvae's movement in response to various stimuli, which involves the dopaminergic system, is of interest in the field of sensory-motor integration. Nevertheless, the conventional methods of movement screening in Petri dishes and multi-well plates are mostly qualitative, uncontrollable, and inaccurate in terms of stimulus delivery and response analysis. We recently presented a microfluidic device built as a versatile platform for fluid flow stimulation and high speed time-lapse imaging of rheotaxis behaviour of zebrafish larvae. Here, we describe for the first time that this microfluidic device can also be used to test zebrafish larvae's sense of the electric field and electrotaxis in a systemic manner. We further show that electrotaxis is correlated with the dopamine signalling pathway in a time of day dependent manner and by selectively involving the D2-like dopamine receptors. The primary outcomes of this research opens avenues to study the molecular and physiological basis of electrotaxis, the effects of known agonist and antagonist compounds on the dopaminergic system, and the screen of novel pharmacological tools in the context of neurodegenerative disorders. We propose that this microfluidic device has broad application potential, including the investigation of complex stimuli, biological pathways, behaviors, and brain disorders.

Neuroscience Research using Small Animals on a Chip: From Nematodes to Zebrafish Larvae

“…For steady high-speed imaging of neural activity in the animals, restricting movements of an animal during experiments is critical. Conventional approaches to restrict the mobility of small animals in a Petri dish are to embed them in agarose gel [13,25,32], to fix them with glue [9,24,[33][34][35], and to apply anesthetic reagents [3,9,13,24,[33][34][35][36][37]. These conventional methods can make small animals prone to irreversible damage.…”

“…Chemotactic behavior of a partially immobilized larva in the chamber where the tail is free to move has been studied using chemical exposure [12,13]. Behavior of freely swimming larva in a U-shaped channel was studied by exposing it to the electric field [25]. To observe behaviors of animals in response to an external stimulus, high-speed imaging is commonly used.…”

“…After the specimen is positioned, neural activity can be monitored using calcium imaging [5,[16][17][18] or microelectrodes to monitor changes in electrical signals [19,20]. Neuronal activities or behavioral responses have been observed upon external stimulus (e.g., chemical [13,21,22] mechanical [23,24], electrical [25,26] or optical [1,[27][28][29]) is given to the organisms. High-throughput drug screening in animal models can be performed using microfluidic devices [30].…”

Single-cell Analysis with Microfluidic Devices

“…[74][75][76] The observation of zebrafish larvae's behavior in response to various stimuli is of interest in the field of nervous science. For instance, Peimani et al 83 developed a versatile microfluidic platform to study the rheotaxis and electrotaxis behavior of zebrafish larvae. As shown in Fig.…”

Zebrafish Larvae's Response to Electricity is Mediated by Dopaminergic Agonists and Antagonists

“…Zebrafish larvae offer several advantages for behavioural studies applicable in examining and creating treatments to combat neurodegenerative and psychiatric disorders. Many microfluidic devices have been designed for manipulation of zebrafish embryos and larvae [1][2][3][4][5][6][7][8] and stimulating them [9][10][11][12][13][14][15][16] to gather information about their neural [15,17] and behavioral [13][14][15][16]18,19] activities in controlled microenvironments. Various stimuli such as thermal [9] , chemical [20] and fluid flow [11] have been tested.…”