Pituitary gonadotropins FSH and LH are oppositely regulated by the activin/follistatin system in a basal teleost, the eel.
European eels are blocked at a prepubertal silver stage due to a deficient production of pituitary gonadotropins. We investigated the potential role of activin/follistatin system in the control of eel gonadotropins. Through the development of qPCR assays for European eel activin β(B) and follistatin, we first analyzed the tissue distribution of the expression of these two genes. Both activin β(B) and follistatin are expressed in the brain, pituitary and gonads. In addition, a striking expression of both transcripts was also found in the retina and in adipose tissue. The effects of recombinant human activins and follistatin on eel gonadotropin gene expression were studied using primary cultures of eel pituitary cells. Activins A and B strongly stimulated FSHβ subunit expression in a time- and dose-dependent manner. In contrast, activin reduced LHβ expression, an inhibitory effect which was highlighted in the presence of testosterone, a known activator of eel LHβ expression. No effect of activin was observed on other pituitary hormones. Follistatin antagonized both the stimulatory and inhibitory effects of activin on FSHβ and LHβ expression, respectively. Activin is the first major stimulator of FSH expression evidenced in the eel. These results in a basal teleost further support the ancient origin and strong conservation of the activin/follistatin system in the control of FSH in vertebrates. In contrast, the opposite regulation of FSH and LH may have emerged in the teleost lineage.
Laboratory of Biology of Aquatic Organisms and Ecosystems, UMR CNRS 7208-IRD 207-UPMC, Muséum National d'Histoire Naturelle, 7 rue Cuvier, CP 32, 75231 Paris Cedex 05, France.
Salima
S
Aroua
Gersende
G
Maugars
Shan-Ru
SR
Jeng
Ching-Fong
CF
Chang
Finn-Arne
FA
Weltzien
Karine
K
Rousseau
Sylvie
S
Dufour
D028341:Activins / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004524:Eels / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000235:genetics / Q000378:metabolism*; D038681:Follistatin / Q000378:metabolism* / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D013997:Time Factors
D038681:Follistatin; D011994:Recombinant Proteins; D028341:Activins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone