Sub-basal increases of GABA enhance the synthesis of TNF-α, TGF-β, and IL-1β in the immune system organs of the Nile tilapia

The cells of the immune and neuronal systems share different receptors for cytokines or neurotransmitters, producing feedback responses between both systems. Cytokines such as IL-1β and TNF-α can induce inflammation; however, the secretion of these molecules can be modulated by anti-inflammatory cytokines, as is the case for TGF-β, as well as by different hormones or neurotransmitters such as the γ-aminobutyric acid (GABA). In this study, we evaluated the secretion of IL-1β, TNF-α, and TGF-β under basal conditions, in the head of the kidney, spleen, thymus, and serum of the Nile tilapia, as well as their release induced by different sub-basal increases of GABA. We found that at the higher dose of GABA these cytokines were synthesised at a higher concentration compared to the control group. These results may suggest that there is feedback between both systems and that GABA plays a role in the modulation of the immune response. [Display omitted] •Recombinant IL-1β, TNF-α and TGF-β2 of O. niloticus was obtained.•Sub-basal doses of GABA increased these cytokines, particularly in serum.•In pronephros, thymus and spleen sub-basal increase of GABA augmented levels of these biomolecules.•TNF-α and TGF-β2 gradually rise in the kidney and spleen, and with the higher dose of GABA in thymus and serum.•GABA plays a modulating role in the immune response of the Nile tilapia.