Atretic preovulatory follicles could be precursors of ovarian lutein cysts in the pig

Ovarian cysts contribute to reduced reproductive performance in pigs. Unfortunately, the mechanism of lutein cysts formation remains unknown. Here, we compared the endocrine and molecular milieus of intact, healthy preovulatory follicles (PF), gonadotropin (eCG/hCG)-induced healthy and atretic-like PF, as well as gonadotropin-provoked and spontaneous ovarian cysts in gilts. Several endocrine and molecular indicators and microRNA were compared in walls of PF and cysts. Intact and healthy PF, showed high estradiol/androstendione and low progesterone levels associated with CYP17A1, HSD17B1, and CYP19A1 elevation and reduced StAR/HSD3B1 protein expression. In contrast, low estradiol/androstendione and high progesterone concentrations, accompanied by decreased CYP17A1, HSD17B1, CYP19A1 and increased HSD3B1 protein abundance, appeared in atretic-like PF, gonadotropin-induced and spontaneous cysts. High progesterone receptor (PGR) protein abundance was maintained in intact and healthy PF, while it dropped in atretic-like PF, gonadotropins-induced and spontaneous cysts. The atretic PF showed high level of TNFα compared to healthy PF. In conclusion, follicular lutein cysts could be recruited from atretic-like PF with lost estrogenic milieu and inability to ovulate. Ovulatory cascade was presumably disrupted by a low PGR and high TNFα levels associated with earlier luteinization of follicular walls. These results suggest a novel mechanism of lutein ovarian cysts development in pigs and, perhaps, other species.

Altrenogest affects the development and endocrine milieu of ovarian follicles in prepubertal and mature gilts†

Altrenogest with gonadotropins is commonly used to synchronize the estrous cycle, but it can also lead to follicular cyst formation, especially in prepubertal gilts. Here, we aimed to investigate how maturity and altrenogest treatment affect the development, endocrine milieu, and molecular control of ovarian follicles. Crossbred prepubertal and mature gilts were challenged or not (control) with altrenogest, and ovaries were collected in the morning on the first day of behavioral estrus. In prepubertal gilts, altrenogest decreased the percentage of primordial and atretic small follicles, but increased large antral follicles when compared with controls. In mature gilts, altrenogest reduced the percentage of primary follicles and elevated the total number of antral follicles. Maturity affected the estradiol level in the follicular fluid of preovulatory follicles, luteinizing hormone (LH)-stimulated cyclic adenosine monophosphate (cAMP) generation, and LH receptor messenger RNA (mRNA) expression in granulosa. Moreover, cytochrome P45017A1 (CYP17A1) mRNA levels in the theca layer were affected and correlated with follicular androstendione and estradiol concentration. Altrenogest negatively affected follicular fluid progesterone concentration and decreased levels of prostaglandin (PG) E2 in prepubertal gilts and PGF2alpha metabolite in mature gilts. LH-stimulated cAMP release in granulosa cells of mature gilts as well as human chorionic gonadotropin- and forskolin-induced cAMP were also affected. In addition, altrenogest downregulated CYP17A1 mRNA in the prepubertal theca layer and PGF2alpha synthase expression in the granulosa and theca layer of mature gilts. To the best of our knowledge, this is the first study to report multiple effects of maturity and altrenogest on the endocrine milieu and molecular regulations governing ovarian follicle development in gilts.

LH release by Cu and Ni salts and metal-GnRH complexes, in vitro

The present studies were undertaken to examine the effect of copper and nickel salts and their complexes with GnRH on LH release from the pig anterior pituitary cells in vitro. The potency of Cu-GnRH and Ni-GnRH binding to GnRH receptors with iodinated GnRH as a radioactive tracer was also verified. The incubation of pig pituitary cells with Cu and Ni acetate salts showed no effect of the studied ions on LH release at any concentration used. However, nickel salt at a lower dose (10(-10) and 10(-9) M) tended to decrease LH output. By contrast, the native GnRH as well as its metal complexes significantly stimulated LH release after three hours of treatment and Cu-GnRH was found to be the most effective. The results showed that Cu and Ni complexes with GnRH but not their acetate salts are effective in LH release from pig pituitary cells collected from adult female pigs.