Affiliation: | a Department of Clinical Chemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden b Animal and Forage Sciences Department, Faculty of Agriculture, Avda. E. Garzón 780, 12900, Montevideo, Uruguay c Department of Molecular and Cellular Biology, Faculty of Veterinary Sciences, Universidad de la República, Lasplaces 1550, 11600, Montevideo, Uruguay d Department of Morphology and Development, Faculty of Veterinary Sciences, Universidad de la República, Lasplaces 1550, 11600, Montevideo, Uruguay e Department of Woman and Child Health, Division for Reproductive Endocrinology, Karolinska Institutet, Stockholm, Sweden |
Abstract: | The concentrations of the oestrogen receptor (ER), and the mRNA levels of ER, progesterone receptor (PR) and insulin-like growth factor I (IGF-I) were characterised in adrenal glands and uterine tissue of adult Corriedale sheep during the breeding season. The sheep were of different sex and gonadal status. Ewes had higher levels of cytosolic ER in the adrenals than the rams (mean±S.E.M.: 7.3±2.0 fmol/mg protein and 2.5±1.0 fmol/mg protein, respectively; P=0.0091) and gonadectomy increased ER (mean±S.E.M.: 2.9±1.2 fmol/mg protein and 8.6±2.3 fmol/mg protein, intact and gonadectomised sheep, respectively; P=0.0071). No differences could be observed in mRNA levels for ER and IGF-I in the adrenal glands of all of the sheep. PR mRNA levels were reduced in ovariectomised ewes and enhanced in castrated rams (sex×gonadal status: P=0.009). PR mRNA levels tended to be higher in ewes in the follicular phase than in ovariectomised ewes and intact rams (P<0.1). All of the animals had positive nuclear staining for ER in the adrenal cortex, but no differences were observed between the groups. In this study, we demonstrated the existence of ER in the adrenal gland of sheep and found varying sensitivity to oestrogens as the ER levels differed among sex and gonadal status. These findings indicate that oestrogens most likely affect steroidogenesis directly at the adrenal cortex and suggest that oestrogens are partly responsible for the sex differences in cortisol secretion in sheep. |