Roles of Estradiol and Gonadotropin-Releasing Hormone in Controlling Negative and Positive Feedback Associated with the Luteinizing Hormone Surge in Ovariectomized Pigs1

Britt, J.H.; Esbenshade, K. L.; Ziȩcik, Adam J.

doi:10.1095/biolreprod45.3.478

Cited by 35 publications

(27 citation statements)

References 31 publications

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“…However, exogenous EB administration between Days 11 and 14 or 15 of the estrous cycle could prolong CL function and the interestrous interval to more than 60 days [13,14]. The peripheral estradiol-17β levels are elevated for 96 h after a single treatment of EB in ovariectomized pigs [29], but there is no significant difference in the plasma estradiol-17β concentrations between EB-treated and control pigs at 9 days after the treatment [30]. In the present study, the plasma concentrations of estradiol-17β in the pseudopregnant gilts after a single treatment of EDP were significantly higher until Day 29 (17 days after the EDP treatment) than those in the cyclic pigs.…”

Section: Discussionmentioning

confidence: 98%

Estrus Synchronization with Pseudopregnant Gilts Induced by a Single Treatment of Estradiol Dipropionate

Noguchi

Yoshioka

Suzuki

et al. 2010

Journal of Reproduction and Development

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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 PGF2α 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-17β level was significantly higher in the EDP-treated gilts than in the control gilts until Day 29. In experiment 2, PGF2α 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 PGF2α treatment was observed in 83% of the pseudopregnant gilts. The interval from the day of the first PGF2α 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 PGF2α treatment. The farrowing rate and average litter size did not differ between the PGF2α-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 PGF2α to EDP-induced pseudopregnant pigs is available for estrus synchronization programs in cyclic pigs. Key words: Estradiol dipropionate, Estrus control, Pig, Pseudopregnancy (J. Reprod. Dev. 56: [421][422][423][424][425][426][427] 2010) t is desirable to have female pigs in estrus at certain times to provide maximum use of intensive pork production facilities. Application of estrus synchronization programs enhances economic performance in the swine industry by reducing the labor required to detect estrus, facilitating the use of artificial insemination (AI) and assisting in batch farrowing. Therefore, being able to control the time of estrus in a breeding herd results in decreased reproductive efforts and costs.Artificially shortening or extending the luteal phase is important for control of the interestrous interval in cyclic animals. The corpus luteum (CL) of the cycling pig generally exhibits resistance to prostaglandin F2α (PGF2α)-induced luteolysis prior to Day 12 of the estrous cycle [1][2][3]. Consequently, multiple administrations of PGF2α in the early luteal phase are required to induce luteolysis of the functional CL and shorten the estrous cycle [2,3]. In contrast to the CL before Day 12 of the estrous cycle, the CL of the pregnant pig easily reacts to exogenous administration of PGF2α [4,5], and prompt estrus can be induced between 4 and 7 days after PGF2α treatment; however, exogenous administration of PGF2α is associated with abortion in pregnant pigs [4,6].In pigs, two phases of ...

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Section: Discussionmentioning

confidence: 98%

Estrus Synchronization with Pseudopregnant Gilts Induced by a Single Treatment of Estradiol Dipropionate

Noguchi

Yoshioka

Suzuki

et al. 2010

Journal of Reproduction and Development

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“…Intact sows in estrous stage (n ¼ 3) and EB-treated OVX sows (n ¼ 3) were used to confirm that the current EB treatment mimics the preovulatory level of circulating estrogens to induce LH surge, as previously reported [21]. For blood sampling, a 16-gauge jugular catheter (Medicut; Nippon Sherwood Medical Industries, Tokyo, Japan) was inserted through the auricular vein into the jugular vein in the animals at least 1 wk before the sampling.…”

Section: Blood Sampling and Lh Assaymentioning

confidence: 99%

Molecular Characterization and Estrogen Regulation of Hypothalamic KISS1 Gene in the Pig1

Tomikawa¹,

Homma²,

Tajima³

et al. 2010

Biology of Reproduction

105

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Kisspeptin-GPR54 signaling plays an essential role in normal reproduction in mammals via stimulation of gonadotropin secretion. Here, we cloned the porcine KISS1 cDNA from the hypothalamic tissue and investigated the effect of estrogen on the distribution and numbers of KISS1 mRNA-expressing cells in the porcine hypothalamus. The full length of the cDNA was 857 bp encoding the kisspeptin of 54 amino acids, with the C-terminal active motif designated kisspeptin-10 being identical to that of mouse, rat, cattle, and sheep. In situ hybridization analysis revealed that KISS1-positive cell populations were mainly distributed in the hypothalamic periventricular nucleus (PeN) and arcuate nucleus (ARC). KISS1 expression in the PeN of ovariectomized (OVX) pigs was significantly upregulated by estradiol benzoate (EB) treatment. On the other hand, KISS1-expressing cells were abundantly distributed throughout the ARC in both OVX and OVX with EB animals. The number of KISS1-expressing neurons was significantly lowered by EB treatment only in the most caudal part of the ARC, but other ARC populations were not affected. The present study thus suggests that the PeN kisspeptin neurons could be responsible for the estrogen positive feedback regulation to induce gonadotropin-releasing hormone/luteinizing hormone (GnRH/LH) surge in the pig. In addition, the caudal ARC kisspeptin neurons could be involved in the estrogen negative feedback regulation of GnRH/LH release. This is the first report of identification of porcine KISS1 gene and of estrogen regulation of KISS1 expression in the porcine brain, which may be helpful for better understanding of the role of kisspeptin in reproduction of the pig.

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“…Ten primiparous crossbred sows (Landrace x Large White) weighing 167 18 kg on Day 1 of lactation were fitted with indwelling vena cava catheters [15] 24 h prior to expected parturition (114 days gestation). Litter size was adjusted to 9-11 piglets at parturition.…”

Section: Animals and Experimental Proceduresmentioning

confidence: 99%

Agonist-Induced Release of Gonadotropin-Releasing Hormone, Luteinizing Hormone, and Follicle-Stimulating Hormone and their Associations with Basal Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone throughout Lactation in Sows

Sesti

Britt

1993

Biology of Reproduction

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Our working hypothesis was that the normal increase in basal secretion of LH and FSH during lactation in sows is paralleled by an increase in readily releasable pools of GnRH, LH, and FSH. Sows fitted with indwelling catheters and nursing 9-11 piglets were sampled on Days 1, 7, 14, and 21 (primiparous sows; n = 10; experiment 1) or Days 7 and 21 (multiparous sows; n = 10; experiment 2) of lactation. On each day, blood was collected at 10-min intervals for 2 h before one member of a pair of sows was infused (i.v.) with saline (n = 5) and the other with the neuroexcitatory amino acid N-methyl-DL-aspartic acid (NMA; 10 mg/kg b.w.) to measure readily releasable GnRH as estimated by LH release. Two hours later, each sow that had received saline was given GnRH (100 micrograms, i.v.) for estimation of releasable pools of pituitary LH and FSH. Responses to NMA and GnRH were estimated by area under the curve (ng.ml-1.min) of serum LH profiles for 1 h (NMA group) or 2 h (GnRH group) after treatment. Basal LH secretion in primiparous sows decreased from Day 1 to Day 7 and then returned to Day 1 values by Day 21. Similarly, in multiparous sows, basal LH was lower on Day 7 than on Day 21. Basal FSH secretion increased linearly as lactation progressed in primiparous and multiparous sows.(ABSTRACT TRUNCATED AT 250 WORDS)

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Roles of Estradiol and Gonadotropin-Releasing Hormone in Controlling Negative and Positive Feedback Associated with the Luteinizing Hormone Surge in Ovariectomized Pigs1

Cited by 35 publications

References 31 publications

Estrus Synchronization with Pseudopregnant Gilts Induced by a Single Treatment of Estradiol Dipropionate

Estrus Synchronization with Pseudopregnant Gilts Induced by a Single Treatment of Estradiol Dipropionate

Molecular Characterization and Estrogen Regulation of Hypothalamic KISS1 Gene in the Pig1

Agonist-Induced Release of Gonadotropin-Releasing Hormone, Luteinizing Hormone, and Follicle-Stimulating Hormone and their Associations with Basal Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone throughout Lactation in Sows

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