Effects of GnRH and the dual regulatory actions of GnIH in the pituitary explants and brain slices of Astyanax altiparanae males

Author(s)

Branco, Giovana Souza ; Melo, Aline Gomes ; Ricci, Juliana M. B. ; Digmayer, Melanie ; de Jesus, Lazaro W. O. ; Habibi, Hamid R. ; Nobrega, Rafael Henrique

• Document type: Journal article
• Source: General and Comparative Endocrinology; v. 273, p. 9-pg., 2019-03-01.

Abstract

The pituitary gonadotropins, Fsh (follicle-stimulating hormone) and Lh (luteinizing hormone), regulate testicular development and functions in all vertebrates. At the pituitary, different signaling systems regulate the synthesis and secretion of the gonadotropins, such as the hypothalamic neuropeptides GnRH (gonadotropin-releasing hormone) and GnIH (gonadotropin-inhibitory hormone). While GnRH exerts stimulatory roles, the actions of GnIH remain controversial for many teleost species. Therefore, the aim of this study was to evaluate the in vitro effects of chicken GnRH2 (cGnRH2) and zebrafish GnIH-3 (zGnIH-3) on the male gonadotropin and GnRH system expression using pituitary explants and brain slices from a neotropical species with economical and ecological relevance, Astyanax altiparanae. Our results showed that in males, cGnRH2 increased fshb and lhb mRNA levels in the pituitary explants. Interestingly, zGnIH-3 has no effect on basal gonadotropin expression, however zGnIH-3 decreased the cGnRH2-induced fshb and lhb transcripts in male pituitary explants. In the male brain slices, zGnIH-3 showed stimulatory effects, increasing gnrh2 mRNA levels. Overall, our results suggested that GnIH seems to have dual regulatory actions on gonadotropin and GnRH2 expression of A. altiparanae males. This study provided basic information on endocrine regulation of A. altiparanae reproduction, and the obtained results will expand our knowledge, improving the reproductive management of this economically important freshwater species. (AU)

• FAPESP's process: 14/07620-7 - Spermatogonial stem cell bank to preserve the genotype of endangered and valuable teleost species
• Grantee: Rafael Henrique Nóbrega
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 15/12104-0 - Effects of cortisol in zebrafish spermatogenesis as mean to understand the role of this steroid during thermal stress induced sex differentiation
• Grantee: Aline Gomes Melo
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 13/20450-0 - Molecular markers and cryopreservation of spermatogonial stem cells of common carp, Cyprinus carpio and zebrafish, Danio rerio
• Grantee: Melanie Digmayer
• Support Opportunities: Scholarships in Brazil - Post-Doctoral