Metabolic effects of CO 2 anaesthesia in Drosophila melanogaster

Abstract

Immobilization of insects is necessary for various experimental purposes, and CO 2 exposure remains the most popular anaesthetic method in entomological research. A number of negative side effects of CO 2 anaesthesia have been reported, but CO 2 probably brings about metabolic modifications that are poorly known. In this work, we used GC/MS-based metabolic fingerprinting to assess the effect of CO 2 anaesthesia in Drosophila melanogaster adults. We analysed metabolic variation of flies submitted to acute CO 2 exposure and assessed the temporal metabolic changes during short- and long-term recovery. We found that D. melanogaster metabotypes were significantly affected by the anaesthetic treatment. Metabolic changes caused by acute CO 2 exposure were still manifested after 14 h of recovery. However, we found no evidence of metabolic alterations when a long recovery period was allowed (more than 24 h). This study points to some metabolic pathways altered during CO 2 anaesthesia (e.g. energetic metabolism). Evidence of short-term metabolic changes indicates that CO 2 anaesthesia should be used with utmost caution in physiological studies when a short recovery is allowed. In spite of this, CO 2 treatment seems to be an acceptable anaesthetic method provided that a long recovery period is allowed (more than 24 h).