EXPRESSION OF LUTEINIZING-HORMONE AND CHORIONIC-GONADOTROPIN RECEPTORMESSENGER-RIBONUCLEIC-ACID IN HUMAN CORPORA-LUTEA DURING MENSTRUAL-CYCLE AND PREGNANCY

In the present study, we examined the expression of LH and CG receptor messenger RNA (mRNA) in human corpora lutea (CL) during the menstrual cycle and pregnancy. Poly(A)-enriched RNA was extracted from CL and a nalyzed by Northern and slot blots, using a radiolabeled complementary RNA probe derived from the human LH receptor complementary DNA. North ern blot analysis indicated the presence of multiple LH receptor mRNA transcripts with molecular sizes of 8.0, 7.0 and 4.5 kilobases in huma n CL during the menstrual cycle. The predominant transcript was 4.5 ki lobases in size. However, no hybridization signals were observed in no ngonadal tissues (heart, liver, and kidney). Densitometric analyses re vealed that the levels of LH receptor mRNA increased from early luteal phase to midluteal phase and subsequently decreased during late lutea l phase. After the onset of menstruation, the LH receptor mRNA level w as undetectable in the regressing CL. Moreover, radioligand receptor a ssay (RRA) showed a close parallelism between LH receptor mRNA levels and LH receptor content in CL throughout the menstrual cycle. LH recep tor mRNA expression was also found in CL during early pregnancy. The l evel of LH receptor mRNA was relatively high in early pregnancy CL, wh ereas LH receptor content was low. Using in situ hybridization, LH rec eptor mRNAs were uniformly expressed in both large and small luteal ce lls during early and midluteal phase and early pregnancy, but not in r egressing CL. In conclusion, these data demonstrate that the regulatio n of LH receptor content in human CL during luteal phase is associated with similar changes in the receptor message levels, suggesting the p hysiological roles for LH receptor mRNA during the menstrual cycle in the human. In addition, the expression of LH receptor mRNA was demonst rated in human CL during early pregnancy.