Gonadotropin subunits of the characiform Astyanax altiparanae: Molecular characterization, spatiotemporal expression and their possible role on female reproductive dysfunction in captivity

Author(s)

de Jesus, Lazaro Wender O. ; Bogerd, Jan ; Vieceli, Felipe M. ; Branco, Giovana S. ; Camargo, Marilia P. ; Cassel, Monica ; Moreira, Renata G. ; Yan, Chao Y. I. ; Borella, Maria I.

• Document type: Journal article
• Source: General and Comparative Endocrinology; v. 246, p. 150-163, MAY 15 2017.
• Web of Science Citations: 4

Abstract

To better understand the endocrine control of reproduction in Characiformes and the reproductive dysfunctions that commonly occur in migratory fish of this order when kept in captivity, we chose Astyanax altiparanae, which has asynchronous ovarian development and multiple spawning events, as model species. From A. altiparanae pituitary total RNA, we cloned the full-length cDNAs coding for the follicle stimulating hormone beta subunit (fshb), the luteinizing hormone beta subunit (lhb), and the common gonadotropin cc subunit (gpha). All three sequences showed the highest degree of amino acid identity with other homologous sequences from Siluriformes and Cypriniformes. Real-time, quantitative PCR analysis showed that gpha, fshb and lhb mRNAs were restricted to the pituitary gland. In situ hybridization and immunofluorescence, using specific-developed and characterized polyclonal antibodies, revealed that both gonadotropin beta subunits mRNAs/proteins are expressed by distinct populations of gonadotropic cells in the proximal pars distalis. No marked variations for lhb transcripts levels were detected during the reproductive cycle, and 17 alpha,20 beta-dihydroxy-4-pregnen-3-one plasma levels were also constant, suggesting that the reproductive dysfunction seen in A. altiparanae females in captivity are probably due to a lack of increase of Lh synthesis during spawning season. In contrast, fshb transcripts changed significantly during the reproductive cycle, although estradiol-17 beta (E-2) levels remained constant during the experiment, possibly due to a differential regulation of E-2 synthesis. Taken together, these data demonstrate the putative involvement of gonadotropin signaling on the impairment of the reproductive function in a migratory species when kept in captivity. Future experimental studies must be carried to clarify this hypothesis. All these data open the possibility for further basic and applied studies related to reproduction in this fish model. (C) 2016 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 14/23451-0 - Molecular characterization and activity of the hypothalamus-pituitary-gonads axis in Astyanax altiparanae (Teleostei, Characiformes) during the reproductive cycle in captivity
• Grantee: Maria Ines Borella
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/19268-8 - Molecular cloning and expression of follicle stimulating (FSH) and luteinizing hormones (LH) and profiles of sex steroids during gonadal differentiation and reproductive cycle of the Characiform Astyanax altiparanae
• Grantee: Lázaro Wender Oliveira de Jesus
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/18297-0 - Molecular characterization, cellular localization, and gene expression studies of the mRNAs coding for the gonadotropin subunits and the gonadotropin receptors of, and the plasma profiles of three sex steroids in Astyanax altiparanae (Teleostei, Characiformes)
• Grantee: Lázaro Wender Oliveira de Jesus
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate