Estrogen and progesterone receptor content in the pituitary gland and uterus of progesterone-primed and gonadotropin releasing hormone-treated anestrous ewes

• Published in: Theriogenology 2002-04, Vol.57 (6), p.1719-1731
• Main Authors: Tasende, C., Meikle, A., Rodrı́guez-Piñón, M., Forsberg, M., Garófalo, E.G.
• Format: Article
• Language: English
• Subjects: Anestrous ewes; Anestrus; Animals; Estrogen; Female; GnRH; Gonadotropin-Releasing Hormone - pharmacology; Organ Size; Ovarian Follicle - anatomy & histology; Ovary - anatomy & histology; Pituitary Gland - anatomy & histology; Pituitary Gland - chemistry; Pituitary Gland - drug effects; Progesterone; Progesterone - pharmacology; Receptor; Receptors, Estrogen - analysis; Receptors, Progesterone - analysis; Sheep - metabolism; Uterus - anatomy & histology; Uterus - chemistry; Uterus - drug effects
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/S0093-691X(02)00665-9

The objective of this work was to investigate the effect of progesterone (P) and gonadotropin-releasing hormone (GnRH) treatment on estrogen receptor (ER) and P receptor (PR) concentrations in the pituitary gland and uterus of anestrous ewes. Ewes were either not treated (group C, n=4); were treated with 0.33 g P-controlled internal drug release (P-CIDR) for 10 days (group P, n=4), with GnRH, 6.7 ng i.v. injections every 2 h for 18 h followed by a 4 μg bolus administration of Receptal at 20 h (group GnRH, n=4), or with a combination of the P and GnRH treatment (group P+GnRH, n=3). Ewes were humanely killed either at the beginning of the experiment (group C), when the CIDR was removed (group P), or 24 h after the GnRH bolus treatment (groups GnRH and P+GnRH). Progesterone treatment increased serum P concentrations, indicating that the treatment was effective. All GnRH treated ewes had similar luteinizing hormone (LH) surges, which lasted 8 h. At slaughter, estradiol (E2) concentrations in the GnRH group were higher than in groups C, P, and P+GnRH. Treatment with GnRH increased more than 10-fold the content of ER and PR in the pituitary gland without altering steroid receptor concentrations in the uterus. When GnRH was combined with P the uterine receptor contents were higher than with P treatment alone. The treatment with P decreased ER and PR content in the uterus, but had no effect on the pituitary gland. The results show that regulation by P and GnRH of ER and PR content in anestrous ewes is tissue-specific.