Five experiments were conducted to study the activity of the
pituitary gland in sheep as influenced by estrogen administered alone
or in combination with progesterone. Particular emphasis was given
to the study of gonadotropic activity.
Mature wethers (experiments I, III, IV and V) or ewes (experiment
II) were utilized as...
Two experiments were conducted to examine the effect of
a cyclopropenoid fatty acid on luteal cell function. In Exp.
1, 12 mature ewes were mated to a fertile ram, assigned to two
groups (n = 6/group) and laparotomized on day 18 of gestation.
Ewes with corpora lutea (CL) in both...
Mares have an atypical hormone profile during pregnancy. Systemic progesterone (P4) levels approach zero by day 220 of gestation. Other reduced pregnanes such as 5α-pregnane-3, 20-dione (5α), 5α-pregnane-3β, 20α-diol (βα), 3β-hydroxy-5α-pregnan-3-one (3β) and 20α-hydroxy-5α-prenan-3-one (20α), increase to near μg/mL levels in the peripheral system of the mare until directly before...
Two experiments were conducted to determine whether in
ewes uterine concentrations of estrogen and progesterone
receptors are affected by the presence of a conceptus or by
the hormonal milieu associated with extremes in photoperiod
to which ewes are exposed.
In Exp.1, nine mature ewes were unilaterally
ovariectomized by removing an...
Experiments were conducted to characterize the nongenomic effects of
progesterone (P4) on binding of oxytocin (OT) to the ovine oxytocin
receptor (OTR) and signal transduction. The dose-response relationship of
P4 to OT binding to the OTR in endometrium was examined. Progesterone
interfered with the binding of OT to the OTR...
Effects of progesterone (P₄) and mifepristone (RU 486) on binding
of oxytocin (OT) to its ovine uterine receptor (OTR) were studied in two
experiments. Two additional experiments were conducted to evaluate
specific binding sites for P4 in endometrial plasma membranes. In Exp.
1, ovariectomized ewes were injected with estradiol-17β (E₂)...
Feeding conjugated linoleic acids (CLA) improves reproductive performance in dairy cows; however, the molecular mechanisms by which CLA improves reproduction are not well understood. Therefore, we evaluated whether the CLA isomers, trans-10, cis-12 CLA and cis-9, trans-11 CLA altered synthesis of steroidogenic hormones in bovine luteal cells by measuring concentrations...