Abstract

The inflammatory reflex modulates the innate immune system, keeping in check the detrimental consequences of overstimulation. A key player controlling the inflammatory reflex is the alpha 7 acetylcholine receptor (alpha 7nAChR). This receptor is one of the signalling molecules regulating cytokine expression in macrophages. In this study, we characterize a novel teleost alpha 7nAChR. Protein sequence analysis shows a high degree of conservation with mammalian orthologs and trout alpha 7nAChR has all the features and essential amino acids to form a fully functional receptor. We demonstrate that trout macrophages can bind a-bungarotoxin (alpha-BTX), a competitive antagonist for alpha 7nAChRs. Moreover, nicotine stimulation produces a decrease in pro-inflammatory cytokine expression after stimulation with poly(l:C). These results suggest the presence of a functional alpha 7nAChR in the macrophage plasma membrane. Further, in vivo injection of poly(I:C) induced an increase in serum ACh levels in rainbow trout. Our results manifest for the first time the functional conservation of the inflammatory reflex in teleosts. (C) 2018 Elsevier Ltd. All rights reserved.