CYCLIC AND MATURATION-DEPENDENT REGULATION OF FOLLICLE-STIMULATING-HORMONE RECEPTOR AND LUTEINIZING-HORMONE RECEPTOR MESSENGER-RIBONUCLEIC-ACID EXPRESSION IN THE PORCINE OVARY

We sought to characterize the ovarian expression of mRNAs for the rece ptors for FSH (FSHr) and LH (LHr) at the different stages of the estro us cycle of the pig and to localize the receptor mRNAs to individual c ell types in follicles and corpora lutea as a function IF: their devel opmental status. Northern blot analyses indicated that multiple FSHr a nd LHr mRNA transcripts occur on Days 0, 4, 7, 12, and 16 of the estro us cycle. In situ hybridization analyses revealed considerable cyclic variation in expression among small, medium, and large follicles. in s mall follicles of both immature prepubertal ovaries and mature adult o varies at all days of the cycle studied, FSHr mRNA expression was stro ngly positive and was spatially restricted to granulosa cells. FSHr mR NA expression was strongly positive in granulosa cells of medium folli cles but had declined in granulosa cells of mature follicles on Day 0. LHr expression in small follicles, in contrast, was spatially restric ted to theca cells and was: estrous cycle-dependent. LHr expression in theca cells was weakly positive in small follicles on Days 12, 0, and 4, was strongly positive in small follicles on Day 7 and in medium fo llicles on Days 12 and 16, and had declined in large mature follicles on Day 0. LHr expression in granulosa cells was negative in small foll icles on Days 4 and 7, weakly positive in medium follicles on Days 12 and 16, and positive in large follicles on Day 0. In degenerating foll icles, LHr mRNA was expressed weakly in the theca cells, and FSHr mRNA expression in granulosa cells was absent. In the corpus luteum, FSHr mRNA was not expressed, but LHr mRNA was expressed in some cells on Da ys 4 and 7, was expressed maximally on Day 12, and had declined partia lly by Day 16. These studies indicate that there is maturation-depende nt regulation of FSHr and LHr expression in the adult porcine ovary. F SHr mRNA content decreases in parallel with FSHr protein content as fo llicles increase in size.