Validation of Hyperbaric Pressure System with Xenon Anesthesia for Drosophila melanogaster

Summary

Gases that seem harmless at atmospheric pressure can induce behaviors like narcosis under hyperbaric conditions. Conventional hyperbaric pressure chambers are costly and labor-intensive. This study presents a straightforward, low-cost method for examining xenon's effects on Drosophila melanogaster at moderate pressures below 4 atm.

Abstract

Under hyperbaric conditions, the elevated concentrations of the ambient gases may elicit a range of behavioral responses in various animals. A substantial portion of these behaviors represents changes in cognitive states that are yet poorly understood. One notable example is general anesthesia. The behavioral effect of several gases under hyperbaric conditions in general anesthesia, or narcosis, has been a long-lasting scientific inquiry, despite the overwhelmingly frequent use of the drugs in medicine. Xenon, classified as a noble gas and an anesthetic agent, is regarded as one of the safest options for general anesthesia in humans. However, it does not anesthetize flies under normobaric conditions. Here, we established a simple experimental setup that increases the ambient pressure up to ~3 atm and allows the study of xenon anesthesia in one of the most popular model organisms, Drosophila melanogaster. This experimental setup further facilitates the study of other gases and their effect under hyperbaric conditions.

Introduction

The two extreme ends of behavioral effects that have been observed in animals under hyperbaric conditions are convulsion by oxygen and narcosis by nitrogen^1,2. Curiously, cognitive impairments such as hallucinations and memory impairment have been reported with nitrogen and hydrogen at pressure values prior to the level of unconsciousness^3,4. Anesthesia induced by xenon, krypton, and nitrous oxide under hyperbaric conditions has been reported before^5,6.

General anest....

Protocol

1. Drosophila melanogaster preparation

1. Collect 20 female and 20 male flies aged 1-3 days for each experiment using CO₂.
2. Rest the selected flies in a vial with food for at least 24 h prior to the experiment at a temperature of ~22 °C.

2. Anesthetic delivery

1. Transfer the gases from their container gas cylinders to the leakproof gas bags for experimental use. For the direct transfer of gas from the container to the bags, use silicone tubing.
2. Attach 25 mm (3.4 mm diameter) silicone tubing to the polypropylene syringe. Then connect the polypropylene syringe to the gas ba....

Results

The method described in this paper allows for the monitoring of both the timing and extent of locomotor activity in flies under hyperbaric conditions. This configuration permits gases like xenon and nitrous oxide, which do not have anesthetic properties under normal conditions, to produce anesthesia in Drosophila melanogaster. To demonstrate this, we experimented with different concentrations of xenon and air. We began establishing the process with 90% xenon and 10% air. Then we demonstrated the methodology's se.......

Discussion

This simple, low-cost setup makes hyperbaric behavioral assays in Drosophila broadly accessible, enabling rapid, reproducible experiments without specialized pressure vessels. However, it presents a few limitations. One of its important compromises is the lower maximum pressure relative to existing setups. The highest pressure we can induce with this setup is ~4 atm, whereas pressure vessels used for Drosophila are reported to reach roughly double that, and systems for mice can go up to 100 atm

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Airtight gas bags (0.5 L)	Techinstro	7440440
Camera	Apple	Iphone 15
Double wire spring hose clamps	sourcing map	a24120200ux2109
Drosophila food mix	Advanced Husbandary	DM900
Drosophila melanogaster	Darwin Biological	LZ-210
Injection pipe	Aitoserlea	B09M8G5BQ8
LED light table	Lairi	M1-3878368
Manometer	Dwyeromega	477AV-8
Metal three-way compression nut stopcock	Sigma Aldrich	Z182184
Polycarbonate syringe (20 mL)	DMC Medical	FD-1031NS
polypropylene syringe (20 mL)	BD	301031
Silicone tubing
Xenon Gas	Chengdu Taiyu Industrial Gases