Estrus synchronization with pseudopregnant gilts induced by a single treatment of estradiol dipropionate.
ABSTRACT The aims of this study were to determine whether a single treatment of estradiol dipropionate (EDP) could induce pseudopregnancy in gilts and to determine the effectiveness of PGF(2alpha) treatment on estrus synchronization in EDP-induced pseudopregnant gilts. In experiment 1, gilts were treated with 20 mg of EDP (n=11) or vehicle (n=5) on Day 12 (Day 0=onset of estrus). Establishment of pseudopregnancy was defined as a lack of estrus and maintenance of the plasma progesterone concentration above 1 ng/ml between Days 12 and 36. Nine of 11 gilts (82%) treated with EDP became pseudopregnant. The plasma estradiol-17beta level was significantly higher in the EDP-treated gilts than in the control gilts until Day 29. In experiment 2, PGF(2alpha) was administered twice with a 24-h interval from Day 36 in pseudopregnant gilts (n=6) or Day 10 in cyclic gilts (control; n=5). Estrus after PGF(2alpha) treatment was observed in 83% of the pseudopregnant gilts. The interval from the day of the first PGF(2alpha) treatment to the onset of estrus and the peak of the LH surge was significantly shorter in the pseudopregnant gilts than in the control gilts. In experiment 3, six pseudopregnant gilts were bred by artificial insemination at the estrus after PGF(2alpha) treatment. The farrowing rate and average litter size did not differ between the PGF(2alpha)-treated pseudopregnant and cyclic gilts. These results indicate that a single treatment of EDP on Day 12 of the estrous cycle can induce pseudopregnancy in pigs and that a convenient protocol for administering PGF(2alpha) to EDP-induced pseudopregnant pigs is available for estrus synchronization programs in cyclic pigs.
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ABSTRACT: Endometrial and conceptus tissues were obtained on Days 10.5, 11, 12, 16 and 25 of pregnancy and Day 25 of pseudopregnancy of gilts and incubated for 6 h in Minimal Essential Medium (5 ml) containing 35 ng [3H]progesterone. Metabolism of [3H]progesterone to oestrone, oestradiol and oestriol was determined by gas and high-pressure liquid chromatography and successive recrystallizations with unlabelled standards. Conceptuses collected between Days 10.5 and 12 were spherical, tubular or filamentous and incubated with 500 mg endometrium and [3H]progesterone. Production of oestrone by spherical conceptuses was not detected, but was 44-47 pg/tubular conceptus and 21 pg/filamentous conceptus. A similar trend was observed for oestradiol. Conceptus tissues from Days 16 and 25 (chorion) were most active in producing oestrone (123 and 520 pg/mg tissue, respectively) and oestradiol (277 and 876 pg/mg tissue, respectively). Endometrial oestrogen production was less than that for conceptus tissue for oestrone and oestradiol on Days 16 and 25 of gestation. Coincubations of endometrium and conceptus tissues had lower oestrogen production than conceptus alone. Endometrium from Day 25 of pseudopregnancy metabolized [3H]progesterone to several non-polar metabolites, but no oestrogens were detected. An unidentified phenolic metabolite of [3H]progesterone was detected in higher quantities than either oestrone or oestradiol; 445 to 461 pg/conceptus at the tubular stage. These results indicate temporal changes in the conversion of [3H]progesterone to oestrogens by conceptus and endometrial tissue from pregnant gilts, but not endometrium from pseudopregnant gilts.J Reprod Fertil 10/1985; 75(1):69-78.
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ABSTRACT: Morphological evidence suggests that LHRH may be secreted into cerebrospinal fluid (CSF), but only in the rhesus monkey has CSF LHRH been found to reflect changes occurring in the LHRH neuroendocrine system. This study investigated whether LHRH is detectable in ovine CSF and, if so, whether its release profile correlates with peripheral LH profiles during pulse and surge conditions. A polyethylene catheter was threaded through a stainless steel guide cannula previously implanted into the third ventricle of an ovariectomized ewe, which enabled continuous CSF withdrawal on repeated occasions. The first experiment (n = 3) showed that peripheral LH concentrations were unaffected by CSF removal at rates of 12, 30, 50, and 100 microliters/min, and the second (n = 4) established that CSF LHRH secretion was pulsatile, with considerable variation in pulse amplitude (6.3 +/- 1.8 pg/ml; range, 1.3-18.7 pg/ml). In the third experiment (n = 6), an endogenous LH surge was induced after progesterone withdrawal and 17 beta-estradiol administration. Although CSF LHRH (15.3 +/- 1.3 h) and peripheral LH (14.8 +/- 1.0 h) surges occurred simultaneously, CSF LHRH concentrations were greater than half-maximal levels for longer (11.0 +/- 0.6 h; P < 0.005) than LH concentrations (6.0 +/- 0.4 h). This is the first study in sheep to reveal the presence of LHRH in CSF and show that it expresses dynamic and longer term changes coincident with peripheral LH fluctuations. CSF LHRH analysis also permits repeated sampling from individuals and, therefore, long term within-individual comparisons.Endocrinology 09/1995; 136(8):3230-7. · 4.72 Impact Factor
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ABSTRACT: Treatment of gilts with 5 mg oestradiol benzoate on Day 9.5, 11, 12.5, 14, 15.5 or Days 14-16 resulted in an interoestrous interval of about 30 days. Administration of oestradiol benzoate daily from Days 11 to 15 or two periods of treatment on Days 11 and 14 to 16 resulted in prolonging CL function beyond 60 days from the pre-treatment oestrus. Endometrial secretory response to oestrogen stimulation, based on the ability of oestrogen to release calcium and uterine protein into the lumen appears to occur after Day 10 of the oestrous cycle. The results suggest that maintenance of prolonged CL function appears to require two periods of oestrogen stimulation. The first period occurs on Day 11 when the endometrium has become responsive to oestrogen stimulation followed by a second prolonged increase in oestrogen stimulation after Day 14. These findings accord with the normal patterns of oestrogen released by pig blastocysts during early pregnancy.J Reprod Fertil 02/1987; 79(1):163-72.