Long-term effects of GnRH agonist, GnRH antagonist, and estrogen plus progesterone treatment on apoptosis related genes in rat ovary

Down-regulation of S100P induces apoptosis in endometrial epithelial cell during GnRH antagonist protocol

BACKGROUND

The gonadotropin-releasing hormone (GnRH) antagonist protocol for in vitro fertilization (IVF) often leads to lower pregnancy rates compared to the GnRH agonist protocol. Decreased endometrial receptivity is one reason for the lower success rate, but the mechanisms underlying this phenomenon remain poorly understood. The S100 calcium protein P (S100P) is a biomarker for endometrial receptivity. Both GnRH antagonist and S100P are involved in mediating cell apoptosis. However, the involvement of S100P in reduced endometrial receptivity during the GnRH antagonist protocol remains unclear.

METHODS

Endometrial tissue was collected at the time of implantation window from patients undergoing the GnRH agonist (GnRH-a) or GnRH antagonist (GnRH-ant) protocols, as well as from patients on their natural cycles. Endometrial cell apoptosis and expression levels of S100P, HOXA10, Bax, and Bcl-2 were assessed. Ishikawa cells were cultured to evaluate the effects that GnRH antagonist exposure or S100P up- or down- regulation had on apoptosis.

RESULTS

Endometrial tissue from patients in the GnRH-ant group showed elevated apoptosis and decreased expression of the anti-apoptotic marker Bcl-2. In addition, endometrial expression of S100P was significantly reduced in the GnRH-ant group, and expression of HOXA10 was lower. Immunofluorescence colocalization analysis revealed that S100P was mainly distributed in the epithelium. In vitro experiments showed that knockdown of S100P in Ishikawa cells induced apoptosis, decreased expression of Bcl-2, while overexpression of S100P caused the opposite effects and decreased expression of Bax. Furthermore, endometrial epithelial cells exposed to GnRH antagonist expressed lower levels of S100P and Bcl-2, increased expression of Bax, and had higher rates of apoptosis. The increased apoptosis induced by GnRH antagonist treatment could be rescued by overexpression of S100P.

CONCLUSIONS

We found that GnRH antagonist treatment induced endometrial epithelial cell apoptosis by down-regulating S100P, which was detrimental to endometrial receptivity. These results further define a mechanistic role for S100P in contributing to endometrial apoptosis during GnRH antagonist treatment, and suggest that S100P is a potential clinical target to improve the success of IVF using the GnRH antagonist protocol.

The effect of GnRH antagonist cetrorelix on Wnt signaling members in pubertal and adult mouse ovaries

Wide application of gonadotropin-releasing hormone (GnRH) agonists and antagonists for clinical purposes determines their effects on ovarian signaling pathways. Our study aimed to determine the localization, expression levels of Wnt signaling members in the pubertal and adult mouse ovary and the impact of GnRH antagonist cetrorelix on these signaling members. 0.5 mg/kg of cetrorelix was injected to 3-and 6-week-old mice for 2 weeks. At the end of injection, ovaries from 5 (5Ce)- to 8-week (8Ce)-old mice were embedded in paraffin for immunohistochemistry and homogenized for western blot to compare with control (5C-8C) and sham groups (5S-8S). WNT2 and WNT4 showed higher expression in thecal and stromal cells in adult mouse ovaries and only WNT4 expression was affected by cetrorelix. FZD1 was localized mainly in oocytes of pubertal ovaries and granulosa cells and oocytes of adult ovaries. FZD1 was reduced by cetrorelix in pubertal ovaries. FZD4 was abundantly localized in thecal and stromal cells of all groups and protein level was not affected by cetrorelix. LRP-6 was expressed mainly in oocytes and stromal cells of pubertal, oocytes of adult ovaries and its expression was reduced by cetrorelix in adult ovaries. CTNNB1 intensity in granulosa cells was the lowest in pubertal and the highest in adult ovaries and its expression was decreased by cetrorelix in adult ovaries. Cetrorelix affected the expression of specific members of the Wnt signaling depending on the developmental stage of mice, pointing out its possible interaction with gonadotropins during pubertal and adult stages.

Noradrenaline modulates the presence of gonadotropin-releasing hormone in ovary. The importance of its interrelation on the ovarian steroidogenesis and apoptosis on dioestrus II in rat

The aim of this work was to investigate if noradrenaline (NA), added in the coeliac ganglion -superior ovarian nerve- ovary system (CG-SON-O) and in ovary incubation, modifies the release of ovarian progesterone (P4), gonadotropin-releasing hormone (GnRH) and oestradiol (E2), and the expression of 3β-HSD and 20α-HSD and proapoptotic bax and antiapoptotic bcl-2 on dioestrus II in the rat. The CG-SON-O system and the ovary were removed and placed in one cuvette containing Krebs-Ringer solution (control groups), and NA was added to the ganglion compartment in the ex vivo system and in the ovary compartment in the ovary incubation (experimental groups). P4, GnRH and E2 were measured by RIA, and gene expression was measured by RT-PCR. In the ex-vivo system, the release of ovarian P4 and GnRH and the expression of 3β-HSD and bax decreased; E2 and bcl-2 increased, and the bax/bcl-2 ratio decreased. However, in the ovary incubation, P4, GnRH, the expression of 3β-HSD and bax increased; E2, the expression of 20α-HSD and bcl-2 decreased while the bax/bcl-2 ratio increased, thus favoring apoptosis. The peripheral nervous system protected the ovary from the apoptotic mechanisms while in the ovary incubation the effect was reverted. Our results indicate that NA regulates ovarian steroidogenesis and apoptosis by modulating GnRH release from the coeliac ganglion and ovary, being NA a possible generator of a GnRH-gonadotropins axis in the ovary. This work is expected to contribute with new evidence of the clinical importance of catecholamines and GnRH in therapy and prevention of ovarian pathologies.

Morphological and enzymatic changes caused by a long-term treatment of female rats with a low dose of gonadoliberin agonist and antagonist

Background

Long-term treatment with gonadoliberin analogs is used to block the hypothalamic-pituitary-gonadal axis. The use of these agents is generally considered to be safe; however, some observations suggest the possibility of adverse effects.

Material/Methods

We investigated whether a 3-months administration of a low dose (6 μg/kg b.w.) of dalarelin – a new agonist, and cetrorelix – a known antagonist of GnRH to female rats causes morphological changes in pituitary gland, ovaries, uterus and liver (HE and VG staining); effects on pituitary, hepatic and blood enzyme activities (histochemical and kinetic methods, respectively), and on the blood lipid profile (colorimetric methods); and to what extent these changes are reversible.

Results

Applying analogs effectively inhibited ovulation, affected the uterine endometrium and changed histological appearance of the liver (e.g., steatosis). They altered activities of marker enzymes of cellular respiration, gluconeogenesis and intracellular digestion in the liver and, partially in the pituitary gland, caused undesirable changes in the activities of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and creatine kinase, and a concentration of cholesterol HDL fraction and triglycerides in the blood. Both morphological and enzymatic effects were more evident after antagonist administration; changes in the blood lipid profile were more evident after agonist administration. In both analogs histological and enzymatic changes persisted a relatively long time after the discontinuation of the treatment.

Conclusions

The low dose of dalarelin and cetrorelix is sufficient to cause limited damage of hepatic cells and may modify the function of pituitary, ovaries, uterus and liver as well as other organs, even after discontinuation of the treatment.