Expression of PTHrP and PTHR (PTH/PTHrP-r) mRNAs and polypeptides in bovine ovary and stimulation of bovine blastocyst development in vitro followingPTHrP treatment during oocyte maturation

Parathyroid hormone related protein (PTHrP) and its receptor have well-esta blished roles in the development and regulation of many tissues, including bone and mammary gland. The objectives of this study were: (1) to character ize the distribution of mRNAs encoding parathyroid hormone (PTH)-related pr otein (PTHrP) and receptor (PTHR) in bovine ovary; (2) to characterize the distribution of PTHrP and PTHR polypeptides in bovine ovary; (3) to examine the influences of PTHrP (1-141) treatment during bovine oocyte maturation in vitro on blastocyst development. mRNAs encoding PTHrP and PTHR were dete cted by in situ hybridization methods in oocytes, and granulosa cells in al l follicles from primordial to large antral. PTHrP and PTHR polypeptides di splayed distinct distribution patterns with PTHrP polypeptides primarily co nfined to oocytes from primordial to large antral follicles. PTHrP polypept ides were detectable but at a reduced level in ovarian stroma and in granul osa and thecal layers. PTHR polypeptides were detected in oocytes of all fo llicular stages but were predominantly found in ovarian stroma, granulosa a nd theca follicular layers. Supplementation of serum-free cSOFMaa oocyte ma turation medium with PTHrP (1-141) resulted in a concentration-dependent in crease in development to the blastocyst stage in vitro. The results suggest that granulosa cells may be a primary site of PTHrP production and release . Oocytes from all follicular stages stained strongly for PTHrP polypeptide s and PTHrP enhanced development to the blastocyst stage in vitro.