Funding Group:

• Award Group:

  • Funder(s):

     Fundação para a Ciência e Tecnologia

  • Award Id(s):

    UIDB/04326/2020

    ,

    PTDC/BIA-BMA/30262/2017

Exposure to high P_CO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl⁻/HCO₃⁻ currents through GABA_A receptors (the GABA_A receptor theory). However, the main evidence for this is that gabazine, a GABA_A receptor antagonist, reverses these effects when applied to the water, assuming that exposure to systems other than the CNS would be without effect. Here, we show the expression of both metabotropic and ionotropic GABA receptors, and the presence of GABA_A receptor protein, in the olfactory epithelium of gilthead seabream. Furthermore, exposure of the olfactory epithelium to muscimol (a specific GABA_A receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABA_A receptors in the olfactory epithelium is not yet clear, this may complicate the interpretation of studies wherein water-borne gabazine is used to reverse the effects of high CO₂ levels on olfactory-driven behaviour in fish.