Fipronil impairs the GABAergic brain responses of Nile Tilapia during the transition from normoxia to acute hypoxia

Abstract

γ‐aminobutyric acid (GABA) is one of the main neurotransmitters involved in the adaptation processes against the damage that hypoxia can cause to the brain. Due to its antagonist action on GABA receptors, the insecticide fipronil can turn the fish more susceptible to the negative effects of hypoxia. This study aimed to understand better if fipronil affects these GABAergic responses of Tilapia ahead to hypoxia. Oreochromis Niloticus (Nile Tilapia) were exposed for 3 and 8 h to fipronil (0.0, 0.1, and 0.5 µg.L−1) under normoxia (dissolved O2 > 6 mg.L−1) and moderate hypoxia (dissolved O2 < 2 mg.L−1) conditions. Briefly, hypoxia caused opposite effects on the gene transcription of the evaluated ionotropic and metabotropic GABA receptors. Unexpectedly, we obtained reduced HIF1A mRNA and brain GABA levels, mostly in the first 3 h of the experiment, for the hypoxic group compared with the normoxia one. Besides that, we also demonstrated that the insecticide fipronil impairs the brain GABAergic signaling of a hypoxia‐tolerant fish during the transition from a normoxic to an acute hypoxic state. Thus, these results predict the relevant impact on the brain metabolic adaptations of fishes exposed to such stressful conditions in an aquatic environment, as well as the effects of fipronil in the GABAergic responses to hypoxia, which in turn may have ecological and physiological significance to hypoxia‐tolerant fishes exposed to this insecticide.

Multi-omics analysis unravels the underlying mechanisms of the escape response of the common strain black carp

“…DEGs enriched in the G protein-coupled receptor signaling pathway node were further enriched in its sub-node: GABA signaling pathway node (GO: 0007214). GABA is the main inhibitory neurotransmitter in the brain of vertebrates, and current research suggests that GABA has potential therapeutic effects in protecting animals from in ammatory damage and improving growth performance under stress (Dourado et al 2023;Zhang et al 2022). In Sus scrofa f. domestica, feeding GABA supplemented feed could improve the antioxidant status caused by transport stress (Bi et al 2020).…”