Primordial Germ Cells (Spermatogonial Stem Cells) of Bullfrogs Express Sex Hormone-Binding Globulin and Steroid Receptors during Seasonal Spermatogenesis

Author(s)

Caneguim, Breno Henrique ^[1] ; Beltrame, Flavia Luciana ^[1] ; da Luz, Juliana Silva ^[2] ; Valentini, Sandro Roberto ^[2] ; Cerri, Paulo Sergio ^[3] ; Sasso-Cerri, Estela ^[3]

Affiliation

^[1] Univ Fed Sao Paulo, Dept Morphol & Genet, Sao Paulo - Brazil

^[2] UNESP Univ Estadual Paulista, Sch Pharmaceut Sci, Dept Biol Sci, Araraquara - Brazil

^[3] UNESP Univ Estadual Paulista, Lab Histol & Embryol, Dept Morphol, Sch Dent, Araraquara - Brazil

• Document type: Journal article
• Source: Cells Tissues Organs; v. 197, n. 2, p. 136-144, 2013.
• Web of Science Citations: 6

Abstract

In vertebrate species, testosterone seems to inhibit spermatogonial differentiation and proliferation. However, this androgen can also be converted, via aromatase, into estrogen which stimulates spermatogonial differentiation and mitotic activity. During seasonal spermatogenesis of adult bullfrogs Lithobates catesbeianus, primordial germ cells (PGCs) show enhanced testosterone cytoplasm immunoexpression in winter; however, in summer, weak or no testosterone immunolabelling was observed. The aim of this study was to confirm if PGCs express stem cell markers - alkaline phosphatase (AP) activity and GFR alpha 1 (glial-cell-line-derived neurotrophic factor) - and verify whether testosterone is maintained in these cells by androgen receptors (ARs) and/or sex hormone-binding globulin (SHBG) in winter. Furthermore, regarding the possibility that testosterone is converted into estrogen by PGCs in summer, the innmunoexpression of estrogen receptor (ER)beta was investigated. Bullfrog testes were collected in winter and in summer and were embedded in glycol methacrylate for morphological analyses or in paraffin for the histochemical detection of AP activity. GFR alpha 1, AR, SHBG and ER beta expression were detected by Western blot and immunohistochemical analyses. The expression of AP activity and GFR alpha 1 in the PGCs suggest that these cells are spermatogonial stem cells. In winter, the cytoplasmic immunoexpression of ARs and SHBG in the PGCs indicates that testosterone is maintained by these proteins in these cells. The cytoplasmic immunoexpression of ER beta, in summer, also points to an ER-mediated action of estrogen in PGCs. The results indicate a participation of testosterone and estrogen in the control of the primordial spernnatogonia during the seasonal spermatogenesis of L. catesbeianus. Copyright (c) 2012 S. Karger AG, Basel (AU)

• FAPESP's process: 09/17895-5 - Morphofunctional evaluation of stem spermatogonia during seasonal spermatogenesis of bullfrog
• Grantee: Estela Sasso Cerri
• Support Opportunities: Regular Research Grants