Modulation of glycoprotein hormone α- and gonadotropin IIβ-subunit mRNA levels in the pituitary gland of mature male African catfish, Clarias gariepinus

Abstract

The cDNAs encoding the glycoprotein hormone α-subunit (GPα) and the gonadotropin IIβ-subunit (GTH IIβ) were cloned from the pituitary gland of the African catfish, Clarias gariepinus. Using RNase protection analysis, we studied the steady-state mRNA levels of GPα as well as GTH IIβ in the pituitary gland of adult male catfish. Castration of adult male catfish resulted in a significant decrease of GTH IIβ mRNA levels, whereas there was no change in the GPα mRNA levels. Treatment of intact males with a single dose of 11-ketotestosterone (11-KT) resulted in dose-dependent increases in mRNA levels of both GPα and GTH IIβ. We conclude that 11-KT, a prominent, non-aromatizable teleost androgen, has a stimulatory effect on the pituitary mRNA levels of GPα and GTH IIβ of adult male fish.