Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Vet. Pharmacology

The present study aimed to investigate the mRNA and protein expressions of nuclear progesterone (P4) receptors; PRA and PRB in mares and cows during the estrous cycle, pregnancy and parturition. RT-qPCR was used to quantify the mRNA expression for PRA and PRB and the difference between mRNA expressions for both genes was compared using the xxCt method. While the Western blot technique was used to compare the protein expression, the band intensity was analyzed using Image J. The tissue P4 concentration was measured using the enzyme immunoassay (EIA). The mRNA and protein expressions for PRA were significantly higher (P<0.0001) in equine placental tissue compared to the PRB mRNA and protein expressions. The expression of PRA mRNA in the cyclic mares was higher (P<0.005) during estrus than diestrus, however, there was no difference in the expression of PRB in the two phases. On the other hand, the protein expression for both PRA and PRB was higher (P<0.005) in estrus compared to the diestrus. The endometrial P4 concentration during diestrus was lower (P<0.005) than in estrus. Both PRA and PRB mRNA (P<0.005) and protein expression (P<0.0005) in cows' myometrial tissues decreased at term compared to the pregnancy. Also, the concentration of P4 in myometrial tissue decreased (P<0.005) in cows at parturition. The expression of mRNA for both isoforms PRA and PRB was high in the early luteal phase (ELP) (P<0.05) compared to the middle and late luteal phases (MLP and LLP). The protein expression of PRB was higher (P<0.05) in ELP compared to MLP and LLP. On the other hand, the protein expression of PRA did not change between all the phases

Issued also as CD