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-1 beta and TNF-alpha can induce inflammation; however, the secretion of these molecules can be modulated by anti-inflammatory cytokines, as is the case for TGF-beta, as well as by different hormones or neurotransmitters such as the gamma-aminobutyric acid (GABA). In this study, we evaluated the secretion of IL-1 beta, TNF-alpha, and TGF-beta 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.