PARENT SESSION
Hormone Receptors

GONADOTROPIN-RELEASING HORMONE RECEPTOR MESSENGER RIBONUCLEIC ACID EXPRESSION IN BOVINE OVARY.

Ramakrishnappa, Nagaraja¹, Merwe, George Karel van der ¹, Rajamahendran, Rajadurai ¹, ¹

ABSTRACT- Gonadotropin-releasing hormone (GnRH) is a hypothalamic neuronal secretary decapeptide that plays key a role in regulation of mammalian reproduction. Recently, the presence of GnRH receptor (GnRHR)-GnRH system and its direct influence on ovarian cellular function has been demonstrated in more than one species, including human. However, there are no reports documenting the intra-ovarian presence of GnRHR-GnRH system or its direct influence on ovarian cellular function in bovine species. Hence, the present study is to investigate the expression of GnRHR messenger ribonucleic acid (mRNA) in bovine ovarian follicle and corpus luteum. Granulosal cells from small (4 mm), medium (5-9 mm) and large follicles (>10 mm) and tissues from different staged corpora lutea, Stage I (Day, 1-4); Stage II (Day, 5-10); Stage III (Day, 11-17) and Stage IV (Day, 18-21) were harvested from paired bovine ovaries collected at a local abattoir. The mRNA from representative samples of different staged follicular granulosa cells and luteal tissues were subjected to reverse transcription-polymerase chain reaction (RT-PCR) using gene sequence specific primers to amplify a 920 bp sized amplicon. Through southern blot procedure, the resultant RT-PCR products were transferred to nylon membranes, and hybridized with a GnRHR sequence specific deoxy ribonucleic acid probe, which was amplified from bovine pituitary mRNA. Granulosa cells from small and medium follicles as well as lutea tissues from stage II and III were shown positive for GnRHR mRNA expression. In conclusion, these findings reveal the presence of GnRHR mRNA in bovine ovarian follicle and corpus luteum for the first time. Further studies are underway to determine the existence of mRNA expression for GnRHR and its ligand, GnRH, in bovine ovary and the possible direct influence of GnRH agonists on ovarian cellular function.

KEY WORDS: GnRH receptor mRNA , granulosa cells, corpora lutea, bovine