Regulation of the type-II gonadotrophin α and β subunit mRNAs by œstradiol and testosterone in the European eel

• Published in: Journal of Molecular Endocrinology
• Main Authors: Quérat, B., Hardy, A., Fontaine, Y.A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Bioscientifica 1991
• Subjects: Anguilla anguilla
• Online Access: http://dx.doi.org/10.1677/jme.0.0070081; https://jme.bioscientifica.com/view/journals/jme/7/1/jme_7_1_011.xml; https://jme.bioscientifica.com/downloadpdf/journals/jme/7/1/jme_7_1_011.xml

ABSTRACT The gonadotrophic function of the European eel ( Anguilla anguilla L.) at the silver stage is very weak: gonadotrophin-releasing hormone (GnRH) secretion is deficient and, moreover, dopamine inhibition overrides GnRH action. At the silver stage, œstradiol stimulates the biosynthesis of the type-II gonadotrophin (GTH-II). To study the molecular mechanism of this activation further, we examined the effect of testosterone and œstradiol administration on pituitary levels of mRNA encoding GTH-II α and β subunits. Corresponding eel cDNA probes and Northern blot analysis were used. After 2 weeks, testosterone and œstradiol implantation resulted in a strong increase in mRNA encoding the GTH-II β subunit (7-fold and 25-fold, respectively) and in a slight, but non-significant, rise in the a subunit mRNA level (1.8-fold and 1.5-fold, respectively). Co-implantation of these two steroids suggested a potentiation of their effects on the β subunit (104-fold) while an additive effect was indicated on the α mRNA level (2.9-fold). Effects were detectable within 4 days and were maximal 4 weeks after implantation. These results indicate that in the European eel at the silver stage, gonadal steroids stimulate differentially the expression of GTH-II subunit genes at a pretranslational level.