REGULATION OF LUTEINIZING HORMONE-RECEPTOR AND FOLLICLE-STIMULATING HORMONE-RECEPTOR MESSENGER-RIBONUCLEIC-ACID LEVELS DURING DEVELOPMENT IN THE NEONATAL MOUSE OVARY

Normal gonadal development is dependent upon stimulation by the gonado tropic hormones, and it is likely that control of ovarian development is regulated by expression of gonadotropin receptors, In this study, q uantitative changes in LH-and FSH-receptor mRNA levels were measured i n the ovary during development in normal mice and in hypogonadal (hpg/ hpg) mice, which lack circulating gonadotropins. The relative abundanc e of alternate transcripts encoding LH and FSH receptors was also dete rmined, Results show that shortened transcripts of the receptors were abundant at all ages, Full-length transcripts of the LH receptor were not detectable until postnatal Day 5 although shortened transcripts en coding the extracellular domain of the receptor were present from birt h, Between Days 5 and 7, LH-receptor transcript levels showed a marked increase in normal animals but no change in hpg/hpg animals, FSH-rece ptor transcripts encoding all domains of the receptor were detectable at low levers at birth, increased in concentration between Days 3 and 5, and peaked at Day 10. In hpg/hpg animals, FSH-receptor mRNA levels were normal up to Day 7 but failed to increase thereafter These result s show that early development of both LH-and FSH-receptor mRNA levels in the ovary is gonadotropin-independent. This coincides with early fo lliculogenesis to the primary stage, Further development of LH-recepto r mRNA levels is gonadotropin-dependent although FSH-receptor mRNA lev els continue to increase independently until early secondary follicles are present.