Neurotrophins in Zebrafish Taste Buds

SIMPLE SUMMARY: Zebrafish is a powerful vertebrate model organism, whose similarities with mammals are fundamental to validate its use for experimental purposes. In this study, the authors demonstrate the presence of neurotrophic factors, namely neurotrophins, in numerous taste bud cells of this fish. The reported results suggest an essential role of these factors in taste bud function. Interestingly, the results described in this study are in accordance with those reported in some mammalian species. Therefore, despite the different anatomical characteristics of the anterior digestive tract in mammals and fish, the taste buds maintain similarities in both shape and functional mechanisms in the two classes. ABSTRACT: The neurotrophin family is composed of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), Neurotrophin 3 (NT3) and NT4. These neurotrophins regulate several crucial functions through the activation of two types of transmembrane receptors, namely p75, which binds all neurotrophins with a similar affinity, and tyrosine kinase (Trk) receptors. Neurotrophins, besides their well-known pivotal role in the development and maintenance of the nervous system, also display the ability to regulate the development of taste buds in mammals. Therefore, the aim of this study is to investigate if NGF, BDNF, NT3 and NT4 are also present in the taste buds of zebrafish (Danio rerio), a powerful vertebrate model organism. Morphological analyses carried out on adult zebrafish showed the presence of neurotrophins in taste bud cells of the oropharyngeal cavity, also suggesting that BDNF positive cells are the prevalent cell population in the posterior part of the oropharyngeal region. In conclusion, by suggesting that all tested neurotrophins are present in zebrafish sensory cells, our results lead to the assumption that taste bud cells in this fish species contain the same homologous neurotrophins reported in mammals, further confirming the high impact of the zebrafish model in translational research.