A Swimming-Induced Zebrafish Exercise Apparatus for Versatile Training Approaches

Summary

The exercise apparatus designed for less fortunate fish facilitates the implementation of diverse exercise protocols with varying intensities by manipulating water flow speed, achievable through rheotaxis.

Abstract

To comprehensively investigate the effects of exercise on health and disease, animal models play a pivotal role. Zebrafish, a widely utilized vertebrate model organism, offers a unique platform for such studies. This study introduced the development of a cost-effective apparatus tailored for zebrafish exercise studies utilizing readily available materials. The device is founded on the principles of a swim tunnel and encompasses a network of pipes and valves linked to a submersible pump. Water flow is meticulously monitored by a sensor and regulated via valves. To assess the apparatus's effectiveness, two training protocols were implemented: moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). Fish were trained collectively, and their swimming performance was assessed through an endurance test. Both training protocols led to improvements in swimming performance following 30 days of training and induced alterations in the molecular response to exercise compared to a sedentary control group. Notably, HIIT demonstrated superior efficiency over MICT. The zebrafish training system proved to be a valuable tool for investigations in exercise physiology and further advances the utility of the zebrafish model in this field.

Introduction

Physical exercise encompasses any bodily movement performed by skeletal muscles that result in increased energy expenditure, with exercise being a structured and repetitive subset of physical activities¹. Exercise, a multifactorial and cost-effective activity involving the entire body, yields numerous health benefits, such as preventing metabolic syndrome and sarcopenia². Consequently, the field of exercise physiology holds significant interest as it seeks to elucidate how the body adapts to the acute stress of exercise, the chronic stress of physical training, and the overall impact of exercise on health

Protocol

The procedures received prior approval from the Animal Use Ethics Committee of the Federal University of São Paulo (CEUA/UNIFESP no. 9206260521). Only adult female wild-type Danio rerio, aged 6 months and weighing 2.5-3 g, were employed in this study. The equipment and reagents needed for the study are listed in the Table of Materials.

1. Custom-made Zebrafish exercise apparatus

NOTE: The exercise apparatus was custom-built. For details, see Figure 1, Supplementary Table 1, Supplementary File 1, and

Results

The exercise apparatus demonstrated remarkable efficiency in regulating flow velocity. To gradually enhance swimming speed, water flow was incrementally increased weekly for all groups, except for the SED group, which was maintained at a constant flow velocity of 0.06 m/s. Notably, the apparatus allowed for a remarkable level of precision, achieving flow velocity adjustments as fine as 0.001 m/s. However, the error rate was 30% at low velocities, such as 0.06 m/s. At high velocities, such as 0.3 m/s and 0.5 m/s, the erro.......

Discussion

In this study, an innovative, cost-effective exercise system was developed inspired by the swim tunnel respirometer from Loligo Systems²¹ and the flume system²² for the comprehensive examination of zebrafish swimming performance. The Umax was determined by systematically increasing water flow in discrete stages, with speed increments occurring over short intervals (20-30 min) until the fish reached exhaustion, which was characterized by three consecutive fatigues or the ina.......

Materials

Name	Company	Catalog Number	Comments
CPVC Female 90-Degree Elbow for Plumbing	Tigre	22150260	3/4-inch
24AWG Wire	Sky Cablo Store		Connection between components in the Perforated Circuit Board (1m)
Acrylic pipe	The Clear Plastic Shop	41138408	3/4-inch
Aquarium Submersible Fish Tank	Aqua Tank		300w
CPVC Pipe	Tigre	10121787	3/4-inch
Female Threaded Gate Water Valve	Tigre	27950310	3/4-inch
Female Threaded Globe Water Valve	Tigre	27940510	3/4-inch
hrough-hole resistor	BXV		10 kΩ, 0.25W t
Lab Support Stand With Clamp with 30 inch rod	Masiye Labs	RSC0001	Support the horizontal pipes
LCD screen	Eichip		16 x 2, model JHD162A
Male x Male Dupont Jumpers	Chyan		Connection between arduino and flow sensor (30 cm)
Perforated Circuit Board single sided	KY WIN ROBOT		5 x 10 cm
Potentiometer	LUSYA	DL-ALPSA01	10kΩ
Roll of Water Blocking Tape	One World	5603131000	To avoid leaks
Silicone hose	Tigre	14211250	2 cm inner
Solder Station	QHTITEC	EU/US PLUG	Arduine system welding
Solder Wire Spool	BEEYIHF	I001-A001-Set	Arduine system welding
Threaded Male Socket and Unthreaded Female Socket CPVC Pipe Fitting	TIgre	35447849	3/4-inch
Tricaine (MS-222)	Sigma-Aldrich	E10521	Anesthetic
UNO-R3 board UNO R3 CH340G+MEGA328P Chip 16Mhz	FSXSEMI		For Arduino UNO R3 Development board
Unthreaded CPVC Tee Pipe Fitting, Female	Tigre	22200267	3/4-inch
Unthreaded Female CPVC Socket Pipe Fitting	Tigre	22170260	3/4-inch
Water Flow Sensor  model YF-B5	Siqma Robotics	SQ8659	1-25 L/min
Water Pump	Sunsun		Model HJ-2041, 3000L/h, 65W
Water reservoir	Custom		30 L