Neuroepithelial cells (NECs) and mucous cells express a variety of neurotransmitters and neurotransmitter receptors in the gill and respiratory air-sac of the catfish Heteropneustes fossilis (Siluriformes, Heteropneustidae): a possible role in local immune defence

• Published in: Zoology (Jena) 2021-10, Vol.148, p.125958-125958, Article 125958
• Main Authors: Lauriano, Eugenia Rita, Capillo, Gioele, Icardo, Jose Manuel, Fernandes, Jorge Manuel Oliveira, Kiron, Viswanath, Kuciel, Michal, Zuwala, Krystyna, Guerrera, Maria Cristina, Aragona, Marialuisa, Germana’, Antonino, Zaccone, Giacomo
• Format: Article
• Language: English
• Subjects: Ach; Air sac; Cholinergic Mucous cells; GAD67/GABA; Gill; Heteropneustes fossilis; nAChR; NECs
• ISSN: 0944-2006; 1873-2720
• DOI: 10.1016/j.zool.2021.125958

•NECs are O2 sensors and store neurotransmitters and immunomodulators in fish.•Steady progress was made in understanding the similarity of the fish and mammalian NECs.•NECs and mucous cells interact in immune response. Heteropneustes fossilis is an air-breathing teleost inhabiting environments with very poor O2 conditions, and so it has evolved to cope with hypoxia. In the gills and respiratory air-sac, the sites for O2 sensing and the response to hypoxia rely on the expression of acetylcholine (Ach) acting via its nicotinic receptor (nAChR). This study examined the expression patterns of neuronal markers and some compounds in the NECs of the gills and respiratory air sac having an immunomodulatory function in mammalian lungs. Mucous cells, epithelial cells and neuroepithelial cells (NECs) were immunopositive to a variety of both neuronal markers (VAChT, nAChR, GABA-B-R1 receptor, GAD679) and the antimicrobial peptide piscidin, an evolutionary conserved humoral component of the mucosal immune system in fish. We speculate that Ach release via nAChR from mucous cells may be modulated by GABA production in the NECs and it is required for the induction of mucus production in both normoxic and hypoxic conditions. The presence of piscidin in mucous cells may act in synergy with the autocrine/paracrine signals of Ach and GABA binding to GABA B R1B receptor that may play a local immunomodulatory function in the mucous epithelia of the gills and the respiratory air sac. The potential role of the NECs in the immunobiological behaviour of the gill/air-sac is at moment a matter of speculation. The extent to which the NECs as such may participate is elusive at this stage and waits investigation.