Cyclic changes in the production of the pituitary gonadotrophic hormones, LH and FSH are essential events in the maintenance of the reproductive system of female mammals. While studies have examined changes in the secretion of LH and FSH during the estrous cycle and demonstrated the importance of these hormones in regulation of ovarian development and gametogenesis, considerably less is known concerning the regulation of the biosynthesis of these hormones. Although initial studies have examined changes in LH subunit mRNA concentrations during the rat and ovine estrous cycles, no information concerning the physiological regulation of FSHβ mRNA concentrations has been available. In the present study we have examined the relationship between pituitary concentrations of LH and FSH subunit mRNAs and the serum concentrations of these gonadotropins. The results demonstrate a very different pattern of change for FSHβ subunit mRNA than that observed for α and LHβ subunit mRNAs. In fact, FSHβ mRNA concentrations decline substantially during the preovulatory period, reaching minimal values at a time when α and LHβ mRNA levels are near maximal. Furthermore, this decline in FSHβ mRNA amounts occurs when serum FSH concentrations are maximal. Thus, FSHβ mRNA concentrations follow a very different pattern than that of serum FSH. In contrast, LHβ mRNA and serum LH concentrations tend to increase at the same time. These findings provide evidence that concentrations of LHβ and FSHβ mRNAs are likely regulated by different mechanisms.
ASJC Scopus subject areas
- Molecular Biology