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Effects of age on follicle and hormone dynamics during the oestrous cycle in mares.
Abstract: The effects of age (young: 5-6 years; intermediate: 10-14 years; old: > or =18 years) on follicle and hormone dynamics during an interovulatory interval (IOI; n = 46) and on preovulatory oocytes and concentrations of follicular fluid factors (n = 44) were studied in mares. Old mares were not approaching senescence, as indicated by regular lengths of the IOI (19-27 days) during the period May-October. The IOI was 1 day longer (P < 0.05) in the old group than in the two younger groups and was associated with a slower (P < 0.05) growth rate of the ovulatory follicle. The old group had diminished follicle activity, as indicated by significantly smaller and fewer follicles. Concentrations of FSH did not differ among age groups, except that the maximum concentration was greater (P < 0.05) in the old group. Concentrations of LH were greater (age x day interaction; P < 0.03) in the young group throughout the ovulatory LH surge and may have played a role in a shorter (P < 0.05) interval from maximum diameter of the preovulatory follicle to ovulation. Maximum circulating concentrations of oestradiol during the preovulatory surge were greatest (P < 0.05) in the young group. No effects of age were detected on oocyte morphology. Concentrations of ovarian steroids in preovulatory follicular fluid were not affected by the age of the mares, but concentrations of free insulin-like growth factor-1 were greater (P < 0.05) in the old group. The results indicate the importance of considering the potential confounding effects of age in experimental protocols and for considering age in the development of theriogenology programmes.
Publication Date: 2008-11-15 PubMed ID: 19007560DOI: 10.1071/rd08121Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research conducted investigates the effect of age on follicle and hormone dynamics throughout the oestrus cycle in mares. It found that age can indeed alter follicle activity and some hormone concentrations, and emphasizes the need to consider age in related experimental protocols and theriogenology programs.
Objective of Research
The main objective of the research was to discern the influence of different age groups (5-6 years, 10-14 years, and 18 or more years) on follicle and hormone dynamics during an interovulatory interval (IOI) in mares. This involved studying follicular fluid factors, preovulatory oocytes, follicle activity and hormone concentrations in relation to the menstrual cycle.
Follicle Activity
- The results revealed that the IOI in older mares, who were not nearing senescence, was one day longer when compared to younger age groups.
- This elongated IOI in the older group was linked to a slower growth rate of the ovulatory follicle.
- Additionally, mares from the older group also demonstrated a significant decrease in follicle activity, evident by fewer and smaller follicles.
Hormone Concentrations
- The study found no differences in FSH (Follicle Stimulating Hormone) concentrations among the three age groups, apart from a higher maximum concentration in the older group.
- Levels of LH (Luteinising Hormone) were consistently higher in the younger groups during the ovulatory LH surge. This might have contributed to a shorter interval between the attainment of maximum diameter of the preovulatory follicle and ovulation.
- Circulating concentrations of oestradiol during the preovulatory surge were highest in the mares from the younger group.
Oocyte Morphology and Ovarian Steroids
- Age did not seem to affect oocyte morphology, showing no notable differences among the three groups.
- Concentrations of ovarian steroids in the follicular fluid did not appear to be influenced by the age of the mares.
- The prominent difference was in the concentration of free insulin-like growth factor-1 (IGF-1), which was significantly higher in the older mares.
Implications of Research
The research findings underscore the necessity of taking age into consideration in experimental protocols. This awareness of age’s influence is also useful in the development of theriogenology programs, as different age groups may require different therapeutic approaches due to alterations in follicle dynamics and hormonal behavior influenced by age.
Cite This Article
APA
Ginther OJ, Gastal MO, Gastal EL, Jacob JC, Siddiqui MA, Beg MA.
(2008).
Effects of age on follicle and hormone dynamics during the oestrous cycle in mares.
Reprod Fertil Dev, 20(8), 955-963.
https://doi.org/10.1071/rd08121 Publication
Researcher Affiliations
- Eutheria Foundation, Cross Plains, WI 53528, USA. ginther@svm.vetmed.wisc.edu
MeSH Terms
- Aging / physiology
- Animals
- Estradiol / metabolism
- Estrous Cycle / physiology
- Female
- Follicle Stimulating Hormone / metabolism
- Follicular Fluid / metabolism
- Horses / physiology
- Insulin-Like Growth Factor I / metabolism
- Luteinizing Hormone / metabolism
- Oogenesis / physiology
- Ovarian Follicle / physiology
- Ovulation / physiology
- Progesterone / metabolism
Citations
This article has been cited 2 times.- Hyde KA, Aguiar FLN, Alves BG, Alves KA, Gastal GDA, Gastal MO, Gastal EL. Preantral follicle population and distribution in the horse ovary. Reprod Fertil 2022 Apr 1;3(2):90-102.
- Yang C, Liu Q, Chen Y, Wang X, Ran Z, Fang F, Xiong J, Liu G, Li X, Yang L, He C. Melatonin delays ovarian aging in mice by slowing down the exhaustion of ovarian reserve. Commun Biol 2021 May 6;4(1):534.
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