Expression of messenger ribonucleic acids of luteinizing hormone and follicle-stimulating hormone receptors in granulosa and theca layers of chicken preovulatory follicles

Abstract

Expression of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) mRNAs was demonstrated in the granulosa and theca layers of the large preovulatory follicles of the chicken ovary by Northern hybridization and reverse transcription-polymerase chain reaction (RT-PCR). Northern hybridization results showed multiple LHR and FSHR mRNA transcripts and the predominant species were 2.3 and 2.5 kb, respectively. The highest abundance of LHR mRNA was found in the granulosa layer of the largest follicle (F1 follicle), while the abundance remained low in the granulosa layers of the third (F3) and fifth largest (F5) follicles. FSH mRNA abundance was the highest in the granulosa layer of F5 follicle, but decreased in the granulosa layers of F3 and F1 follicles. In the theca layers of all the three follicles examined LHR and FSHR mRNAs were extremely low. These results were confirmed by RT-PCR experiment which involved coamplification of LHR or FSHR mRNA and beta-actin mRNA as the internal control. The LHR PCR product was sequenced and indicated 92.2% homology with the corresponding region of the quail LHR cDNA. This study indicated that the marked increase in expression of LHR mRNA in granulosa layer of the F1 follicle might be important for LHR protein synthesis and succeeding bonus progesterone production in F1 follicle destined to ovulation. However, higher expression of FSHR mRNA in the granulosa layer of the less mature follicles may be involved in the differentiation and maturation of granulosa cells in these follicles.