Follicle-stimulating hormone receptor and its messenger ribonucleic acid are present in the bovine cervix and can regulate cervical prostanoid synthesis

The hypothesis that FSH regulates the bovine cervical prostaglandin E-2 (PG E(2)) synthesis that is known to be associated with cervical relaxation and opening at the time of estrus was investigated. Cervical tissue from pre-e strous/estrous, luteal, and postovulatory cows were examined for 1) the pre sence of bovine (b) FSH receptor (R) and its corresponding mRNA and 2) the effect of FSH on the PGE(2) regulatory pathway in vitro. The presence of bF SHR mRNA in the cervix (maximal during pre-estrus/estrus) was demonstrated by the expression of a reverse transcription (RT) polymerase chain reaction (PCR) product (384 base pairs) specific for bFSHR mRNA and sequencing. Nor thern blotting revealed three transcripts (2.5, 3.3, and 3.8 kilobases [kb] ) in cervix from pre-estrous/estrous cows. The level of FSHR (75 kDa) was s ignificantly higher (p < 0.01) in Western blots of pre-estrous/estrous cerv ix than in other cervical tissues. There was a good correlation between the 75-kDa protein expression and its corresponding transcript of 2.55 kb thro ughout the estrous cycle as described by Northern blot analysis as well as RT-PCR. Incubation of FSH (10 ng/ml) with pre-estrous/estrous cervix result ed in a 3-fold increase in the expression of FSHR and a 2-fold increase in both G protein (alpha(s)) and cyclooxygenase II. FSH (5-20 ng/ml) significa ntly increased(p < 0.01) cAMP, inositol phosphate (p < 0.01), and PGE(2) (p < 0.01) production by pre-estrous/estrous cervix but not by cervix at the other stages, We conclude that bovine cervix at the time of the peripheral plasma FSH peak (pre-estrus/estrus) contains high levels of FSHR and respon ds to FSH by increasing the PGE(2) production responsible for cervical rela xation at estrus.