Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
J Exp Biol. 2022 Feb 1;225(3). doi: 10.1242/jeb.243112. Epub 2022 Jan 31.
Exposure to high PCO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl-/HCO3- currents through GABAA receptors (the GABAA receptor theory). However, the main evidence for this is that gabazine, a GABAA 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 GABAA receptor protein, in the olfactory epithelium of gilthead seabream. Furthermore, exposure of the olfactory epithelium to muscimol (a specific GABAA receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABAA 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.
暴露在高 PCO2/低 pH 海水中会引起鱼类的行为改变；这种变化的一个可能解释是 GABA A 受体的 Cl-/HCO3- 电流发生反转（GABA A 受体理论）。然而，支持这一理论的主要证据是，gabazine（一种 GABA A 受体拮抗剂）在应用于水中时会逆转这些效应，假设暴露于中枢神经系统以外的系统不会产生影响。在这里，我们展示了 gilthead 海鲷嗅上皮中代谢型和离子型 GABA 受体的表达，以及 GABA A 受体蛋白的存在。此外，暴露于 muscimol（一种特定的 GABA A 受体激动剂）会增加或减少对某些气味的表观嗅觉敏感性。因此，尽管 GABA A 受体在嗅上皮中的确切功能尚不清楚，但这可能会使那些使用水传播 gabazine 来逆转高 CO2 水平对鱼类嗅觉驱动行为影响的研究的解释变得复杂。
