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The Journal of Experimental Biology

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Killifishes, GABA -- Metabolism, Anoxia -- Effect of GABA on, Neurotransmitters, Antioxidants


In most vertebrates, a lack of oxygen quickly leads to irreparable damages to vital organs, such as the brain and heart. However, there are some vertebrates that have evolved mechanisms to survive periods of no oxygen (anoxia). The annual killifish (Austrofundulus limnaeus) survives in ephemeral ponds in the coastal deserts of Venezuela and their embryos have the remarkable ability to tolerate anoxia for months. When exposed to anoxia, embryos of A. limnaeus respond by producing significant amounts of γ-aminobutyric acid (GABA). This study aims to understand the role of GABA in supporting the metabolic response to anoxia. To explore this, we investigated four developmentally distinct stages of A. limnaeus embryos that vary in their anoxia tolerance. We measured GABA and lactate concentrations across development in response to anoxia and aerobic recovery. We then inhibited enzymes responsible for the production and degradation of GABA and observed GABA and lactate concentrations, as well as embryo mortality. Here, we show for the first time that GABA metabolism affects anoxia tolerance in A. limnaeus embryos. Inhibition of enzymes responsible for GABA production (glutamate decarboxylase) and degradation (GABA-transaminase and succinic acid semialdehyde dehydrogenase) led to decreased mortality, supporting a role for GABA as an intermediate product and not a metabolic end product. We propose multiple roles for GABA during anoxia and aerobic recovery in A. limnaeus embryos, serving as a neurotransmitter, an energy source, and an antioxidant.


© 2020. Published by The Company of Biologists Ltd.


NOTICE: this is the author’s version of a work that was accepted for publication in The Journal of Experimental Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in The Journal of Experimental Biology, 223(20).



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