Characterization of the levels of messenger ribonucleic acid that encode for luteinizing hormone receptor during the luteal phase of the primate menstrual cycle.

Abstract

The present study was designed to characterize the expression of LH receptor messenger RNA (mRNA) in the primate corpus luteum throughout the luteal phase of the menstrual cycle. We obtained corpora lutea from cynomolgus monkeys at defined stages of the luteal phase. LH receptor mRNA was demonstrated in monkey ovarian sections by in situ hybridization with a 35S-labeled antisense RNA probe derived from rat LH receptor complimentary DNA. The hybridization signals were confined to thecal layers of antral follicles and corpus luteum. Using the same LH receptor cDNA, the pattern of expression of mRNA encoding for LH receptor during the luteal phase was determined by Northern blot analysis. Four species of mRNA migrating at 1.0, 4.0, 7.5, and 8.0 kilobase (kb) were identified; the 4.0 kb size mRNA species was more abundant than the other three species. Quantitative analysis of the 4.0 kb band of mRNA throughout the luteal phase by densitometry revealed that the levels of LH receptor mRNA were low during the early luteal phase (days 3-5 of the luteal phase). A progressive increase in the message levels was observed from the early luteal phase to the end of the luteal phase. By days 11-12, there was a significant increase in the message levels (less than 0.05) which further increased during the late luteal phase (days 13-15). After menstruation, the levels became undetectable. In contrast, mRNA levels for 3 beta-hydroxysteroid dehydrogenase, a key enzyme involved in luteal steroidogenesis, were high shortly after ovulation and declined throughout the remainder of the luteal phase. These results indicate that after ovulation and luteinization, the expression of mRNAs that encode for specialized luteal cell proteins is differentially regulated.