Oestrogen and progesterone receptor binding capacity and oestrogen receptor alpha expression (ERα mRNA) along the cervix of cycling ewes

Abstract

The aim of the present work was to study the oestrogen receptor (ER) and progesterone receptor (PR) binding capacity and the oestrogen receptor alpha (ERα) mRNA concentration in cranial and caudal cervix during the ovine oestrous cycle. Cervical samples of synchronised Corriedale ewes were obtained on Day 1 (n = 7), 6 (n = 6) or 13 (n = 7) after oestrus detection (Day 0). The ER and PR binding capacity by ligand-binding assay and the ERα mRNA concentration by solution hybridisation in both cranial and caudal zones of the cervix were determined. The ER and PR binding capacity were higher (P < 0.005) on Day 1 than on Days 6 and 13 in both cranial and caudal zones. The ERα mRNA concentrations were higher (P < 0.0001) on Day 1 than on Days 6 and 13 only in the caudal zone. The PR binding capacity and ERα mRNA concentration were higher (P < 0.005) in the caudal than in the cranial zone on Day 1. The ER and PR expression in the ovine cervix varied during the oestrous cycle in agreement with the known upregulation exerted by oestrogen and downregulation exerted by progesterone. Differences in ER and PR expression along the longitudinal axis of the ovine cervix were found, reflecting histological and functional differences between the cranial and caudal zones.