Nerve growth factor (NGF), belonging to the neurotrophin family, functions as a key regulator in various essential processes within both the peripheral and central nervous systems. Concurrently, numerous studies have demonstrated that this neurotrophin is also active in non-neuronal organs, including reproductive tissues. Although extensive research has been performed in mammals, information regarding NGF and its receptor TrkA in the reproductive organs of other vertebrates, such as teleost fish, remains limited. To broaden current understanding of NGF and TrkA in vertebrate gonadal models, this study investigates the expression profiles of ngf and trka mRNA in the testes and ovaries of adult zebrafish. Through chromogenic and fluorescent in situ hybridization analyses, we reveal that in zebrafish testes, ngf and trka are predominantly localized in spermatogonia B and spermatocytes. In the ovaries, both genes are detected across various oocyte developmental stages. Collectively, these observations indicate that NGF and its receptor play a conserved role in the reproductive physiology of vertebrates.
