Effects of gonadotropin-releasing hormone agonist on steroidogenesis in the rat ovary

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.

Delayed puberty in spontaneously hypertensive rats involves a primary ovarian failure independent of the hypothalamic KiSS-1/GPR54/GnRH system

Spontaneously hypertensive (SH) rats, extensively used as experimental models of essential human hypertension, display important alterations in the neuroendocrine reproductive axis, which manifest as markedly delayed puberty onset in females but whose basis remains largely unknown. We analyze herein in female SH rats: 1) possible alterations in the expression and function of KiSS-1/GPR54 and GnRH/GnRH-receptor systems, 2) the integrity of feedback mechanisms governing the hypothalamic-pituitary-ovarian axis, and 3) the control of ovarian function by gonadotropins. Our data demonstrate that, despite overtly delayed puberty, no significant decrease in hypothalamic KiSS-1, GPR54, or GnRH mRNA levels was detected in this strain. Likewise, in vivo gonadotropin responses to ovariectomy and systemic kisspeptin-10 or GnRH administration, as well as in vitro gonadotropin responses to GnRH, were fully preserved in SH rats. Moreover, circulating LH levels were grossly conserved during prepubertal maturation, whereas FSH levels were even enhanced from d 20 postpartum onwards. In striking contrast, ovarian weight and hormone (progesterone and testosterone) responses to human chorionic gonadotropin (CG) in vitro were profoundly decreased in SH rats, with impaired follicular development and delayed ovulation at puberty. Such reduced hormonal responses to human CG could not be attributed to changes in LH/CG or FSH-receptor mRNA expression but might be linked to blunted P450scc, 3beta-hydroxy steroid dehydrogenase, and aromatase mRNA levels in ovaries from SH rats. In conclusion, our results indicate that the expression and function of KiSS-1/GPR54 and GnRH/GnRH-receptor systems is normal in SH rats, whereas ovarian development, steroidogenesis, and responsiveness to gonadotropins are strongly compromised.

Massive ascites and hydrothorax after leuprolide acetate administration in a down-regulated woman undergoing assisted reproduction

OBJECTIVE

To present an atypical case of massive ascites and hydrothorax after leuprolide acetate administration in a down-regulated woman undergoing assisted reproduction.

DESIGN

Case report.

SETTING

Centre for Reproductive Medicine, Department of Obstetrics, Gynaecology, and Neonatology, University of Parma, Parma, Italy.

PATIENT(S)

A 41-year-old, nulliparous, white woman who developed massive ascites and hydrothorax after administration of 0.50 mg/day of subcutaneous leuprolide acetate, beginning at the midluteal phase.

INTERVENTION(S)

Down-regulation with the gonadotropin-releasing hormone analogue was discontinued, and therapy was started with furosemide 50 mg/day for 10 days.

MAIN OUTCOME MEASURE(S)

Successful medical reduction of ascites and hydrothorax.

RESULT(S)

Resolution of symptoms.

CONCLUSION(S)

A comprehensive MEDLINE search revealed this to be the first reported case of massive ascites and hydrothorax after leuprolide acetate administration (0.5 mg daily) in a down-regulated woman undergoing assisted reproduction. This case can be explained by an increase in capillary permeability, which resulted in a rapid fluid shift from the intravascular space into the third space. We believe that ascites in our patient resulted from an increase in estradiol in the ovaries, due to a direct action of the gonadotropin-releasing hormone analogue on the corresponding ovarian receptors in the first few days after the start of therapy.

Comparative analysis of different puberty inhibiting mechanisms of two GnRH agonists and the GnRH antagonist cetrorelix using a female rat model

GnRH agonists are the established treatment of precocious puberty caused by premature stimulation of gonadotropin secretion. It has been reported that after an initial stimulation ("flare-up") they reduce LH secretion by desensitization of pituitary GnRH receptors. Little has been published about the use of GnRH antagonists such as cetrorelix to control the onset of puberty and whether they are potentially advantageous compared with GnRH agonists. We conducted two multigroup experiments (12 and 10 d, respectively) treating prepubertal/peripubertal female rats with either the GnRH agonist triptorelin or buserelin and compared them with rats treated with the GnRH antagonist cetrorelix and controls to assess the effects on pubertal progress and serum hormones. In the second experiment, the effects of buserelin and cetrorelix on gene expression of the GnRH receptor, LH-beta, FSH-beta, and the alpha subunit genes in the pituitary were also investigated. Cetrorelix, triptorelin, and buserelin retarded the onset of puberty as determined by delayed vaginal opening, lower ovarian weights, and lower serum estradiol levels. However, although LH and FSH levels were stimulated by both agonists, they were inhibited by cetrorelix. In the cetrorelix versus buserelin experiment, pituitary gene expression of the GnRH receptor and LH-beta subunit were significantly lower in cetrorelix treated rats compared with controls whereas buserelin had little effect. Expression of FSH-beta and alpha subunit were stimulated by buserelin but not by cetrorelix. Even though all three of these GnRH analogues inhibited gonadal development and delayed the onset of puberty, the GnRH agonists had stimulating and inhibiting effects on the pituitary-gonadal axis whereas cetrorelix exerted only inhibiting effects. We conclude from this female rat model that cetrorelix may offer advantages for a more controlled medical treatment of precocious puberty compared with GnRH agonist treatment.

Effects of gonadotrophin-releasing hormone agonists on human ovarian steroid secretion in vivo and in vitro-results of a prospective, randomized in-vitro fertilization study

The aim of this prospective randomized study was to compare the effects of two gonadotrophin-releasing hormone (GnRH) agonists, buserelin and triptorelin, on human ovarian follicular steroidogenesis, oocyte fertilization and IVF treatment outcome. Ovulatory, healthy women undergoing IVF were treated either with human menopausal gonadotrophin (HMG) alone or with HMG and one of the two GnRH agonists. Serum and follicular fluid hormonal concentrations and cultures of luteinizing granulosa cells obtained during follicular aspiration were analysed. GnRH agonist treatment significantly affected steroidogenesis both in serum and follicular fluid. In follicular fluid, progesterone and oestradiol concentrations were significantly elevated while testosterone concentrations were significantly lower in the triptorelin group. The ratios of testosterone/progesterone, oestradiol/progesterone but not oestradiol/testosterone concentrations were significantly affected by GnRH agonist administration. Similarly, the steroidogenic activity of luteinizing granulosa cells in vitro was significantly decreased in women treated with GnRH agonists. Women treated with GnRH agonists had significantly more fertilized oocytes and cleaving embryos. The results indicate a marked effect of GnRH agonists on the pattern of ovarian follicular steroidogenesis that cannot be explained solely by changes in gonadotrophin concentrations.