Can the Presence of Ovarian Corpus Luteum Modify the Hormonal Composition of Follicular Fluid in Mares?

Abstract

The hypothesis of this study was to investigate if the presence of corpus luteum (CL) in one ovary could modify the hormonal content of follicular fluid (FF) in the follicles. Sixty ovaries were taken after the slaughter of 30 clinically healthy mares. In relation to the sizes, the follicles were classified into three different categories, as small (20–30 mm), medium (31–40 mm) and large (≥41 mm). Blood samples were collected from the jugular vein of mares before their slaughter, and then the FF samplings were extracted from each single follicle. The ovaries that were collected were classified into two groups, according to the presence (CL-bearing) or absence (non-CL-bearing) of CL. The serum and FF samples were analysed for progesterone (P4), oestradiol-17β (E2), testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA). Intrafollicular P4 concentrations in large follicles of CL-bearing groups were lower than for non-CL-bearing ones. Intrafollicular E2 concentrations increased with the increase of the follicle diameter in both groups, CL-bearing and non-CL-bearing. However, in the FF with a large and medium follicle size, E2 concentrations were significantly higher in non-CL-bearing groups than in CL-bearing groups. T and A4 significantly increased in the large and medium follicle sizes when compared to the small follicle sizes in both groups, but higher concentrations in the non-CL-bearing group were obtained. Intrafollicular DHEA significantly decreased with the increase of the follicular diameter in both groups. Steroid hormones in FF dynamically changed, according to the presence or not of CL in the ovary. This study brings new knowledge on the role of the CL in the follicular hormonal composition in mares.

The Roles of the miRNAome and Transcriptome in the Ovine Ovary Reveal Poor Efficiency in Juvenile Superovulation

“…The cyclic activity of the ovary is mainly influenced by reproductive hormones [ 48 , 49 ]; under the stimulation of FSH and LH, the follicles undergo primary, secondary, and antral stages, and only a few of them reach the pre-ovulatory stage [ 50 ]. After superovulation treatment in the present study, we found that there was no significant difference in the concentrations of FSH and LH in jugular vein serum between lambs and adult sheep.…”

Lipid metabolites, interleukin-6 and oxidative stress markers in follicular fluid and their association with serum concentrations in mares

“…All year round, the maturation rate of equine oocytes was directly correlated with follicle size (Hinrichs and Schmidt, 2000). The follicular development in mares influences the follicular metabolites, electrolytes (Satué et al 2019) and steroid hormones (Satué et al 2020). Interestingly, FF components, related to the oocytes developmental competence, have been clearly described in cows (Annes et al 2019), camels (El-Shahat et al 2018, goats (Junior et al 2018), and sows (Bertoldo et al 2013).…”

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“…Furthermore, steroid hormones in follicular fluid dynamically change according to the presence or not of CL in the ovary of mares. Satué et al (2020) found in the follicular fluid of large and medium follicle sizes, E2 concentrations were significantly higher than in non-CL groups. Also, testosterone and androstenedione were significantly increased in larger follicles in the non-CL groups; also, intrafollicular Effect of exogenous progestogen treatment was confirmed on P4 plasma concentration produced by CLs, at D8 after ovulation, and on the average diameter of the pre-ovulatory follicle.…”