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Corpus luteum life span and pituitary oestrogen and progesterone receptors in cyclic and gonadotrophin-releasing hormone-treated anoestrous ewes
C.
Tasende A B C,
M.
Rodríguez-Piñón A,
S.
Acuña A,
E. G.
Garófalo A,
M.
Forsberg B
A
Biochemistry, Department of Molecular and Cellular Biology, Faculty of Veterinary, Montevideo, Uruguay.
B
Department of Biomedical Sciences and Veterinary Public Health, Division of Diagnostic Imaging and Clinical Pathology, SLU, Uppsala, Sweden.
C
Corresponding author. Email: ctasende@adinet.com.uy
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Reproduction, Fertility and Development 17(7) 721–726 http://dx.doi.org/10.1071/RD05058
Submitted: 24 May 2005
Accepted: 16 September 2005
Published online: 2 November 2005
Abstract
The present study investigated the pituitary oestrogen (ER) and progesterone (PR) receptor concentrations in ewes during the oestrous cycle in the breeding season (n = 19), and in anoestrous ewes treated with gonadotrophin-releasing hormone (GnRH) (n = 11) and anoestrous ewes treated with progesterone + GnRH (n = 11). The pituitary ER and PR concentrations at the expected time of ovulation and in the early and late luteal phases were measured by binding assay. The pattern of pituitary ER and PR concentrations in the progesterone + GnRH-treated ewes resembled the pattern found during the normal oestrous cycle, with ER and PR concentrations decreasing from the time of ovulation to the early luteal phase. In contrast, in ewes treated with GnRH alone, ER and PR concentrations increased in the early luteal phase, which may increase the inhibitory effects of steroid hormones on luteinising hormone secretion, ultimately leading to the development of subnormal luteal phases.
Keywords:
subnormal luteal phase.
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