Experimental studies on the positive feedback effect of progesterone, 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone on the pituitary release of LH and FSH in the human female. The estrogen priming of the progesterone feedback on pituitary gonadotropins in the eugonadal woman

Adrenocorticotropic hormone elicits gonadotropin secretion in premenopausal women

STUDY QUESTION

Does adrenocorticotropic hormone (ACTH) induce gonadotropin release in premenopausal women?

SUMMARY ANSWER

Administration of ACTH stimulates gonadotropin release, most likely by stimulation of the production of cortisol, in premenopausal women.

WHAT IS KNOWN ALREADY

In animal models, acute activation of the hypothalamic-pituitary-adrenal (HPA) axis has been shown to induce gonadotropin release in the presence of sufficiently high estrogen levels. However, it is unknown whether the HPA axis has a similar influence on gonadotropin release in humans.

STUDY DESIGN, SIZE, DURATION

This study had a mixed factorial design. A total of 60 healthy female participants participated in the experimental study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study sample comprised three distinct hormonal-based populations according to their levels of progesterone (PROG) and estradiol (E2): (i) low-PROG-low-E2, (ii) low-PROG-high-E2 and (iii) high-PROG-high-E2 women. A low dose (1 µg) of ACTH was administered to all study participants. Serum steroid and gonadotropin concentrations were measured prior to, and at 30 and 90 minutes after, intravenous ACTH administration.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean serum cortisol levels increased significantly following ACTH administration in all groups (P < 0.001). Similarly, the serum levels of 17-OH-PROG, androstenedione, dehydroepiandrosterone and testosterone increased significantly in all groups (P < 0.01). The low-PROG-high-E2 and high-PROG-high-E2 groups exhibited a significant increase in LH and FSH levels (P < 0.001), whereas the low-PROG-low-E2 group demonstrated blunted LH and FSH responses to ACTH administration (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

Testing was performed during the luteal phase of the natural menstrual cycle. Testing during the follicular phase might have elicited premature, or more pronounced, LH surges in response to ACTH administration.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest a novel mechanism by which the adrenal cortex functions as a mediator of gonadotropin release. These findings contribute to a greater understanding of the influence of acute stress on reproductive endocrinology.

STUDY FUNDING/COMPETING INTERESTS

Funding was received from the Erasmus University Medical Center. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

EudraCT Number 2012-005640-14.

The progesterone positive feedback effect in women after ovariectomy

Various ovarian substances regulate the secretion of gonadotrophins during the menstrual cycle, but there are still several unclarified issues. The aim of this study was to investigate the positive feedback effect of progesterone during the immediate period following ovariectomy. Experiments were performed in 12 normally cycling women (aged 39-49 years). Following abdominal hysterectomy plus bilateral ovariectomy performed on cycle day 3 (day 0), the women received either estradiol via skin patches (days 0-7, n = 6, group 1) or estradiol as above plus vaginal progesterone (days 1-7, n = 6, group 2). Serum estradiol values increased similarly in the two groups. After the operation, serum progesterone levels decreased significantly in group 1, while in group 2 they remained stable becoming higher than in group 1 (p < 0.05). An LH and an FSH surge occurred in group 2 with the values after the peak returning to the pre-surge baseline. In contrast, in group 1 LH and FSH levels following an initial decrease, increased gradually until the end of the experiment. These results demonstrate that, despite a variable response to estrogens, the positive feedback effect of progesterone remained intact immediately after ovariectomy in women. It is suggested that it is the combining action of estradiol and progesterone that can ensure the expression of a positive feedback mechanism in women.

Distribution and metabolism of 20 alpha-hydroxylated progestins in the female rat

The C21 steroids, progesterone and 20 alpha-hydroxy-4-pregnen-3-one (20 alpha-DHP) play pivotal roles in the initiation, timing and maintenance of ovulatory function and pregnancy in female mammals. They also have growth factor and central nervous system (CNS) effects; some of these are non-genomic effects mediated through 5 alpha-reduced and 3 alpha-hydroxylated derivatives. These studies examined the in vivo uptake and conversion of 20 alpha-DHP in selected CNS sites and peripheral tissues after injection of [(3)H]-20 alpha-DHP. The effects of steroid mass, time after injection, and ovariectomy, adrenalectomy and estradiol treatment were assessed in the pineal gland, preoptic area of the hypothalamus (POA), medial basal hypothalamus (MBH), midbrain, cerebellum, cerebral cortex, anterior pituitary (AP), uterus and skeletal muscle. Tissue extracts were analyzed by scintillation counting and chromatography to quantify and localize 20 alpha-DHP and its 5 alpha-reduced derivatives. Injection of increasing mass of [(3)H]-20 alpha-DHP to ovariectomized/adrenalectomized (ovx/adx) rats results in a linear increase in (3)H-steroid 10 min post injection in all tissues. (3)H-steroid content increases with time over 1 h post injection in the pineal, AP and uterus. Tissue differences in (3)H-steroid level are observed with higher levels in pineal, MBH, POA, AP and midbrain than in cerebral cortex and cerebellum, and in uterus, ovary and adrenal than in muscle. Ovariectomy, adrenalectomy and estradiol treatment affect (3)H-steroid levels in a tissue dependent manner, and the metabolites of 20 alpha-DHP in MBH and AP differ between groups. The findings demonstrate that target tissues, including areas of the CNS, are able to selectively take up and retain 20 alpha-DHP, and also support a physiological role for this progestin and its metabolites in modulation of CNS and reproductive functions.

From physiology to clinics--20 years of experience with pulsatile GnRH

The physiological and the pathophysiological basis of unvariant pulsatile administration of gonadotrophin-releasing hormone (GnRH) as well as the clinical results are reviewed. Pulsatile administration of GnRH not only proved to be a very effective treatment mode but also became an important tool for research in the central control of pituitary and ovarian function under normal and disease conditions.

Vaginal progesterone administration in physiological doses normalizes raised luteinizing hormone levels in patients with polycystic ovarian syndrome

A raised luteinizing hormone (LH) level is a typical finding in the polycystic ovarian syndrome (PCOS). This inappropriate elevation of LH is thought to interfere with normal follicular development and ovulation. The resulting chronic anovulation is associated with the absence of the luteal phase increase in secretion of progesterone and inhibin. Progesterone can exert both a positive and negative feedback action on LH secretion, but inhibition is thought to occur following prolonged exposure to progesterone. Therefore, the aim of this study was to see if exogenously administered progesterone in physiological doses would normalize circulating LH concentrations in patients with PCOS. Vaginal progesterone was administered twice daily in a dose of 100 mg, at 12 h intervals, to ten women with PCOS. Serum samples were taken on alternate days for radioimmunoassay of follicle stimulating hormone (FSH), LH, estradiol, progesterone and inhibin. To determine the effect of progesterone on LH secretory dynamics in PCOS, LH pulse studies were carried out prior to treatment, and on day 10 of progesterone administration in four of the ten subjects. Mean serum progesterone concentrations reached 51 nmol/l by 4 days after exogenous progesterone treatment, and remained in the mid-luteal phase range, as established in 12 normal cycles, during the use of the vaginal suppository. The mean serum LH concentration had fallen significantly (p < or = 0.01) after 8 days of treatment, and continued to fall progressively until the end of progesterone administration. Serum LH concentrations had fallen into the normal follicular phase range by 14 days (mean 5.5, range 3.4-10.9 IU/l; normal follicular phase range 1.8-10.0 IU/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of 20 alpha-dihydroxyprogesterone on the estrogen-induced bioactive luteinizing hormone surge in ovariectomized monkeys

Progestins facilitate estrogen induction of the preovulatory luteinizing hormone (LH) surge. A biologically weaker progestin, 20 alpha-dihydroxyprogesterone, is reportedly increased at midcycle, but the importance of 20 alpha-dihydroxyprogesterone in regulating LH release has not been systematically studied. We therefore evaluated the effect of 2 doses of 20 alpha-dihydroxyprogesterone on the bioactive LH surge onset in ovariectomized monkeys. Chronically cannulated monkeys (n = 10) received estradiol (E2) benzoate (50 micrograms/kg) with and without subsequent 20 alpha-dihydroxyprogesterone injections (50 micrograms/kg, n = 3 and 100 micrograms/kg, n = 3). Blood was collected every 15 minutes over preselected intervals and the plasma assayed for bioactive LH and gonadal steroids. Low-dose 20 alpha-dihydroxyprogesterone administration resulted in periovulatory peripheral 20 alpha-dihydroxyprogesterone levels and did not advance the bioactive LH surge onset. In contrast, high-dose 20 alpha-dihydroxyprogesterone resulted in supraphysiological 20 alpha-dihydroxyprogesterone levels, slight increases in progesterone levels, and significant advancement of the surge over E2 benzoate treatment alone. We conclude that periovulatory levels of 20 alpha-dihydroxyprogesterone do not play a role in modulating the estrogen-induced bioactive LH surge.

Premature luteinizing hormone surges in menopausal gonadotropin-stimulated cycles in monkeys: lack of initiation by progesterone

The occurrence of spontaneous luteinizing hormone (LH) surges in women receiving human menopausal gonadotropins (hMG) for in vitro fertilization-embryo transfer is a significant clinical problem. One hypothetical mechanism is that premature progesterone (P) secretion occurring in the high estradiol (E2) milieu produced by hMG triggers the spontaneous LH surge. To investigate this possibility, 11 rhesus and cynomolgus monkeys were stimulated with hMG. At maximal ovarian stimulation, monkeys were injected with 15 micrograms/kg P (n = 3), 30 micrograms/kg P (n = 3), or 1,000 IU human chorionic gonadotropin (hCG) (n = 5; controls). Blood for E2, P, and LH was drawn twice daily in the periovulatory period and daily before and after this period. Laparoscopy was performed after P or hCG injection. In the 6 monkeys receiving P, no LH surges were detected. Further, postinjection P profiles and laparoscopy showed no evidence of ovulation. Controls demonstrated laparoscopic and hormonal evidence of ovulation. These findings suggest that P does not trigger LH surges in hMG-stimulated cycles.

Positive and negative feed-back effect of progesterone on luteinizing hormone secretion in post-menopausal women

Progesterone is known to exert a biphasic feedback effect on luteinizing hormone (LH) secretion in animals and it has been demonstrated that this effect is dependent upon both duration of exposure to progesterone and the dose administered. In this paper we sought to determine whether a similar biphasic effect exists in humans. The pattern of LH secretion was assessed in six healthy oestrogen treated post-menopausal women before and after they were given progesterone (50 mg/day) for 1 and 7 days. Progesterone treatment for 1 day resulted in a significant elevation in the basal serum LH concentration and in individual LH pulse amplitude with no change in LH pulse frequency. In contrast, progesterone treatment for 7 days increased LH pulse amplitude with no change in basal serum LH concentrations and a significant reduction in LH pulse frequency. We concluded that firstly, progesterone does exert a biphasic feedback effect on LH secretion and that the nature of this effect is determined by the duration of exposure to the progesterone stimulus. Secondly, as LH pulsatility has been shown to be an accurate indicator of GnRH pulsatility, that the reduction in LH pulse frequency after a long exposure to progesterone is due to a hypothalamic effect of progesterone whereas the positive feedback effect may be the result of a pituitary or hypothalamic action.

Effect of high dose exogenous oestrogen on midcycle luteinizing hormone surge in human spontaneous cycles

Induction of multiple follicular development in women results in supraphysiological serum oestradiol (E2) levels and marked reduction of the endogenous LH surge. To examine whether high serum E2 levels at midcycle can suppress gonadotrophin secretion during the LH surge, five normally ovulating women were given an intramuscular injection of 10 mg oestradiol benzoate 6-42 h before the expected endogenous LH surge. The results were compared with the preceding untreated control cycle. Serum E2 levels at the onset of the LH surge (mean +/- SEM) were significantly higher in the oestrogen-treated cycles (13,600 +/- 1963 pmol/l) than in the control cycles (1012 +/- 116 pmol/l) (P less than 0.001). The duration of the LH surge (64.8 +/- 2.2 h) and LH peak levels (136 +/- 9.6 mIU/ml) in the oestrogen treated cycles were similar to those in the control cycles (61.2 +/- 3.9 and 119 +/- 9.4 mIU/ml respectively) (mean +/- SEM). The cycle day on which the LH surge started and the size of the dominant follicle, as assessed by ultrasound, did not differ significantly between the two groups of cycles. These results show that in spontaneous cycles the endogenous LH surge is neither reduced nor amplified by the induction of supraphysiological serum E2 levels during the immediate pre-ovulatory stage.

Case report. Successive pregnancies in a patient with premature ovarian failure

A woman, age 28 yr, visited the gynecological endocrine clinic for oligomenorrhea and primary infertility. Serum FSH and LH levels were high and estrogen concentrations were subnormal. In spite of the presence of high and sustained gonadotropin concentrations, resumption of ovarian function with evident ovulation resulted in the first pregnancy after clomiphene therapy. Four years later the patient did not respond to clomiphene but intramuscular progesterone was effective in induction of ovulation, followed by the second pregnancy. The effect of progesterone on hypergonadotropic ovarian failure is discussed.

The effect of danazol on gonadotropin secretion during the follicular phase of the menstrual cycle

The effects of danazol on pulsatile luteinizing hormone (LH) release, basal LH and follicle-stimulating hormone serum levels, gonadotropin release induced by estradiol (E2) and gonadotropin-releasing hormone were examined in five eugonadal women. Danazol administration resulted in a significant suppression of follicle-stimulating hormone serum levels. LH concentrations and LH pulse frequency appeared to be reduced, but these changes did not reach statistical significance. The pituitary response to exogenous gonadotropin-releasing hormone was not altered. The stimulatory effect of E2 on LH secretion was completely abolished in one subject, severely diminished in three subjects, and unchanged in one subject. In addition, the time course of this response was altered. Serum prolactin concentrations were lowered, whereas basal E2 and progesterone levels did not seem to be affected.

Studies on ovarian and adrenal steroids at different phases of the menstrual cycle. 1. Dynamic changes during the periovulatory period

In order to assess the periovulatory interrelationships between the plasma levels of estradiol, estrone, 17-hydroxyprogesterone, progesterone, cortisol and biologically active lutropin (LH), peripheral blood samples withdrawn from 12 normally menstruating women at 07.00, 15.00 and 23.00 h. during seven days of the midcycle period were analyzed. The estradiol peak varied between 0.86 and 1.50 nmol/l; it preceded the LH peak in 11 subjects and occurred simultaneously with it in 1 case. Although the peak levels of estradiol were significantly higher than those associated with the LH peak, there was no significant difference between the estradiol levels at the LH peak and those found during the 32-hour period prior to the LH peak. Calculation of the estradiol to estrone ratios revealed the existence of two groups of subjects with significantly different ratios. In one group the estradiol levels were significantly lower and those of estrone significantly higher than in the other group. No difference was found between these two groups concerning the other hormonal indices measured. No significant variation was found in the estradiol, estrone and LH levels during the day; however, there was a significant overnight increase in their levels during 3 to 4 days preceding the day of the LH peak. A significant rise in 17-hydroxyprogesterone levels occurred 8 h. before the earliest rise in LH and progesterone levels; on the other hand, in none of the subjects did the first rise in progesterone levels precede the first significant elevation of LH levels.

Plasma levels of FSH and LH in patients with gonadal dysgenesis during sequential estrogen and progestogen therapy

We describe the plasma levels of FSH and LH in ten patients with gonadal dysgenesis during treatment with a low dosage sequential estrogen-progestogen preparation. The daily dose of mestranol ranged from 12.5--50 microgram. Norethisterone was administered from day 16 onwards, the dose ranging between 0.75 and 1.5 mg. It was shown that 25 microgram mestranol was effective in lowering the elevated FSH levels significantly (alpha < 0.001). LH levels remained unaffected. The combination of 25 microgram mestranol and 1 mg norethisterone produced an increase of FSH and LH within 12 h, maximum levels being reached within 36 h after which there was a progressive decline. Low doses of estrogen and progestogen appeared capable of evoking physiological hypothalamic and pituitary responses in patients with gonadal dysgenesis. The doses employed were sufficient to induce breast development, growth of sexual hair, and withdrawal bleeding and were probably not high enough to induce rapid bone maturation and consequent stunting of growth.

The mechanism of action of a new low-dosed combined oral contraceptive

The effect of a new low-dosed combined oral contraceptive (OC) containing 37.5 microgram ethinyl estradiol and 0.75 mg lynestrenol (Ovoresta M) upon gonadotropin release and follicular activity was studied in two groups of normally cyclic women. When the administration of the OC was started on day 1 of the cycle, the normal pattern of gonadotropin secretion was disrupted, and the midcycle LH and FSH peak was abolished. The mean level of LH and FSH was somewhat lower than in normal cycles, but the difference was not significant. In one case, serum estradiol rose to the level of the normal cycle indicating follicular activity. Even though there was a rise in serum estradiol to normal values when the OC was started on day 10 of the cycle (in 4/5), both the midcycle LH and FSH surge and ovulation were suppressed (in 3/4). The pituitary response to 100 microgram LH-RH on day 21 was impaired. The LH-response correlated significantly with the serum estradiol concentration. In summary, the low-dosed OC exerts its effect by interfering with follicular ripening and inhibiting the preovulatory LH surge.

The impairment of progesterone-induced pituitary release of prolactin and gonadotropin in patients with hypothalamic chronic anovulation

Sequential administrations of progessively increasing amounts of estradiol benzoate (EB) for five days followed by 10 mg. of progesterone (P) elicited a prompt pituitary release of luteinizing hormone, follicle-stimulating hormone, and prolactin in normal women during the early follicular phase but not in women with normogonadotropic hypothalamic chronic anovulation with or without associated hyperprolactinemia. Since hypothalamic dopamine functions as an inhibitor for the secretion of both prolactin and gonadotropin, we postulate that sequential EB-P stimulation for simultaneous release of gonadotropin and prolactin may be mediated by a reduction of hypothalamic dopamine in response to progesterone. The failure of patients with hypothalamic chronic anovulation to respond to this sequential ovarian steroid feedback demonstrated in this study may indicate the presence of dopaminergic dysfunction and that this test may prove to be useful in delineating hypothalamic function in amenorrhea patients.