Temporal interrelationships among luteolysis, FSH and LH concentrations and follicle deviation in mares.
Abstract: The effect of altered LH concentrations on the deviation in growth rates between the 2 largest follicles was studied in pony mares. The progestational phase was shortened by administration of PGF2alpha on Day 10 (Day 0=ovulation; n=9) or lengthened by daily administration of 100 mg of progesterone on Days 10 to 30 (n=11; controls, n=10). All follicles > or = 5 mm were ablated on Day 10 in all groups to initiate a new follicular wave. The interovulatory interval was not altered by the PGF2alpha treatment despite a 4-day earlier decrease in progesterone concentrations. Time required for growth of the follicles of the new wave apparently delayed the interval to ovulation after luteolysis. The FSH concentrations of the first post-ablation FSH surge were not different among groups. A second FSH surge with an associated follicular wave began by Day 22 in 7 of 11 mares in the progesterone group and in 0 of 19 mares in the other groups, indicating reduced functional competence of the largest follicle. A prolonged elevation in LH concentrations began on the mean day of wave emergence (Day 11) in the prostaglandin group (19.2 +/- 2.2 vs 9.0 +/- 0.7 ng/mL in controls; P<0.05), an average of 4 d before an increase in the controls. Concentrations of LH in the progesterone group initially increased until Day 14 and then decreased so that by Day 18 the concentrations were lower (P<0.05) than in the control group (12.9 +/- 1.6 vs 20.2 +/- 2.6 ng/mL). Neither the early and prolonged increase nor the early decrease in LH concentrations altered the growth profile of the second-largest follicle, suggesting that LH was not involved in the initiation of deviation. However, the early decrease in LH concentrations in the progesterone group was followed by a smaller (P<0.05) diameter of the largest follicle by Day 20 (26.9 +/- 1.7 mm) than the controls (30.3 +/- 1.7 mm), suggesting that LH was necessary for continued growth of the largest follicle after deviation.
Publication Date: 2000-03-24 PubMed ID: 10730980DOI: 10.1016/S0093-691X(00)00240-5Google Scholar: Lookup
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- Clinical Trial
- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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This study examines how changing LH (Luteinizing Hormone) concentrations affect the growth rates of the two largest follicles in pony mares, specifically during the progestational phase. The study showed that neither an early increase nor decrease in LH levels alter the growth profile of the second-largest follicle, indicating that LH is not involved in the initiation of growth deviation; however, an early decrease in LH levels correlated with a smaller diameter of the largest follicle, suggesting that LH is necessary for the continued growth of the largest follicle post-deviation.
Methodology of the Study
- The researchers studied the impact of altered LH concentrations on the growth deviation between the two largest follicles in pony mares.
- The progestational phase was controlled: in some cases shortened with the administration of PGF2alpha on day 10 (Day 0 being the day of ovulation), while in others it was lengthened with a daily administration of progesterone on days 10 to 30. All follicles 5mm in size were ablated on day 10 to trigger a new follicle growth wave.
- The resultant changes in interovulatory interval, FSH and LH concentrations, and growth deviation of the follicles were then recorded and analyzed.
Key Findings
- Even if the progestational phase was reduced, the interovulatory interval was not affected by the PGF2alpha treatment despite a 4-day earlier drop in progesterone concentrations.
- The initiation of a new follicular wave appeared to delay the interval to ovulation post-luteolysis.
- FSH concentrations following the first post-ablation surge were consistent across all groups, showing no effect of alteration in the LH levels on this surge.
- A significant portion of the mares in the progesterone group experienced a second FSH surge associated with a new follicular wave, suggesting the functional competence of the largest follicle was reduced.
- Neither an early and prolonged increase nor an early decrease in LH concentrations appear to alter the growth profile of the second-largest follicle. This suggests that LH may not play a significant role in initiating deviation in follicle growth rates.
- An early drop in LH concentrations in the progesterone group corresponded with a smaller diameter of the largest follicle, suggesting that LH may be necessary for continued growth of the largest follicle post deviation.
Cite This Article
APA
Gastal EL, Gastal MO, Nogueira GP, Bergfelt DR, Ginther OJ.
(2000).
Temporal interrelationships among luteolysis, FSH and LH concentrations and follicle deviation in mares.
Theriogenology, 53(4), 925-940.
https://doi.org/10.1016/S0093-691X(00)00240-5 Publication
Researcher Affiliations
- Animal Health and Biomedical Sciences, University of Wisconsin, Madison 53706, USA.
MeSH Terms
- Animals
- Corpus Luteum / physiology
- Dinoprost / administration & dosage
- Female
- Follicle Stimulating Hormone / blood
- Horses / physiology
- Luteinizing Hormone / blood
- Ovarian Follicle / physiology
- Ovulation
- Progesterone / administration & dosage
- Progesterone / blood
- Time Factors
Citations
This article has been cited 3 times.- Segabinazzi LGTM, Gilbert RO, Ambrosia RL, Bergfelt DR, Samper JC, Peterson EW, French HM. Structural and Functional Dynamics of the Ovary and Uterus during the Estrous Cycle in Donkeys in the Eastern Caribbean. Animals (Basel) 2022 Dec 24;13(1).
- Ginther OJ, Beg MA, Gastal EL, Gastal MO, Baerwald AR, Pierson RA. Systemic concentrations of hormones during the development of follicular waves in mares and women: a comparative study. Reproduction 2005 Sep;130(3):379-88.
- Ginther OJ, Gastal EL, Gastal MO, Bergfelt DR, Baerwald AR, Pierson RA. Comparative study of the dynamics of follicular waves in mares and women. Biol Reprod 2004 Oct;71(4):1195-201.
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