The role of ligand-gated chloride channels in behavioural alterations at elevated CO2 in a cephalopod

Details

• Journal Title:
  Journal of Experimental Biology
• Personal Author:
  Thomas, Jodi T. ; Spady, Blake L. ; Munday, Philip L. ; Watson, Sue-Ann
• NOAA Program & Office:
  CoRIS (Coral Reef Information System)
• Description:
  Projected future carbon dioxide (CO2) levels in the ocean can alter marine animal behaviours. Disrupted functioning of γ-aminobutyric acid type A (GABAA) receptors (ligand-gated chloride channels) is suggested to underlie CO2-induced behavioural changes in fish. However, the mechanisms underlying behavioural changes in marine invertebrates are poorly understood. We pharmacologically tested the role of GABA-, glutamate-, acetylcholine- and dopamine-gated chloride channels in CO2-induced behavioural changes in a cephalopod, the two-toned pygmy squid (Idiosepius pygmaeus). We exposed squid to ambient (∼450 µatm) or elevated (∼1000 µatm) CO2 for 7 days. Squid were treated with sham, the GABAA receptor antagonist gabazine or the non-specific GABAA receptor antagonist picrotoxin, before measurement of conspecific-directed behaviours and activity levels upon mirror exposure. Elevated CO2 increased conspecific-directed attraction and aggression, as well as activity levels. For some CO2-affected behaviours, both gabazine and picrotoxin had a different effect at elevated compared with ambient CO2, providing robust support for the GABA hypothesis within cephalopods. In another behavioural trait, picrotoxin but not gabazine had a different effect in elevated compared with ambient CO2, providing the first pharmacological evidence, in fish and marine invertebrates, for altered functioning of ligand-gated chloride channels, other than the GABAAR, underlying CO2-induced behavioural changes. For some other behaviours, both gabazine and picrotoxin had a similar effect in elevated and ambient CO2, suggesting altered function of ligand-gated chloride channels was not responsible for these CO2-induced changes. Multiple mechanisms may be involved, which could explain the variability in the CO2 and drug treatment effects across behaviours.
• Keywords:
  GABA Ocean Acidification Squids Ocean Acidification Animal Science And Zoology Aquatic Science Ecology, Evolution, Behavior And Systematics Gabazine Insect Science Ligand-gated Chloride Channels Molecular Biology Ocean Acidification Physiology Picrotoxin Squid

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• Source:
  J Exp Biol (2021) 224 (13): jeb242335
• DOI:
  https://doi.org/10.1242/jeb.242335
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:54ab9c3b1d359cc4e6915ea4231b57c13c8bc5ec0c6b94ec489b80c6a2466d4a
• Download URL:
  https://repository.library.noaa.gov/view/noaa/47742/noaa_47742_DS1.pdf
• File Type:
  [PDF - 882.21 KB ]