Corpus luteum: composition and function

Daytime Variation in Serum Progesterone During the Mid-Luteal Phase in Women Undergoing In Vitro Fertilization Treatment

OBJECTIVE

To investigate whether mid-luteal serum progesterone (P₄) exhibits significant fluctuations during a 12-h daytime period in women undergoing in vitro fertilization (IVF) and to explore whether the extent of these fluctuations could impact the interpretation of luteal progesterone levels in a clinical setting.

DESIGN

Explorative pilot study.

SETTING

Public hospital-based fertility unit.

PATIENTS

Ten women undergoing IVF treatment.

INTERVENTION

Seven days after oocyte pick-up, patients underwent frequent repeated blood sampling (every 60 min for 12 h and during two of these hours, every 15 min). Serum samples were analyzed for progesterone, estradiol, and luteinizing hormone (LH).

MAIN OUTCOME MEASURES

Daytime fluctuations in s-progesterone and s-estradiol.

RESULTS

There was a significant positive correlation between median P₄ levels and the magnitude of P₄ variations-women with median P₄ < 60 nmol/l had clinically stable P₄ levels throughout the day, while patients with median P₄ > 250 nmol/l exhibited periodic P₄ peaks of several hundred nanomoles per liter. These endogenous P₄ fluctuations were observed irrespective of the type of stimulation protocol or mode of triggering of final oocyte maturation and despite the fact that LH was under the detection limit at the time of measurement. Simultaneously, large fluctuations were seen in s-estradiol.

CONCLUSION

Monitoring of early to mid-luteal P₄ levels in IVF cycles may be valuable in the planning of individualized luteal phase support in the attempt to increase reproductive outcomes. The prerequisite for luteal phase monitoring is, however, that the validity of a single measured P₄ value is reliable. We show for the first time, that a single P₄ measurement in the low progesterone patient quite accurately reflects the corpus luteum function and that the measurement can be used to detect IVF patients with a need of additional exogenous luteal P₄ administration.

Endocrinological actions of Unkei-to, a herbal medicine, and its clinical usefulness in anovulatory and/or infertile women

Kampo medicine (Chinese herbal medicine) has been reported to be effective in the treatment of pituitary-ovarian dysfunction in young women and in the treatment of undefined symptoms in perimenopausal women. It has been considered that both the diagnosis and treatment of ovulatory failure in adolescent girls or young women are necessary for the sake of future fertile capacity. However, treatment for the above patients is not easy as steroid hormones and strong stimulators of ovulation should not be recommended because of the several side-effects it causes. Furthermore, young women, especially teenagers, seem to be reluctant to visit gynecology clinics. A number of herbal medicines have been used for many centuries in China and Japan for the treatment of menstrual disorders and infertility. In general, the traditional Chinese herbal prescriptions are rather inexpensive and safe with little side-effects, and have properties for normalizing biological balances. Unkei-to is known to stimulate the synthesis and release of gonadotropins in the rat pituitary. In humans, Unkei-to is known to be effective in various menstrual disorders, abnormal uterine bleeding, and infertility. In the treatment of ovulatory failure, recent dynamic studies have revealed the mechanism by which Unkei-to stimulates the diencephalon-pituitary-ovarian axis in humans. In this paper, we critically review the clinical data available (to date) in order to assess the efficacy of Unkei-to in inducing ovulation in several types of ovulatory disturbances. (Reprod Med Biol 2003; 2: 45-61).

Successful pregnancy after transient ovarian failure following treatment of symptomatic leiomyomata

OBJECTIVE

To report a case of transient ovarian failure after treatment of symptomatic leiomyomata and review other iatrogenic causes of transient ovarian failure.

DESIGN

Case report and literature review.

SETTING

University-affiliated private practice.

PATIENT(S)

A 35-year-old woman with symptomatic leiomyomata.

INTERVENTION(S)

Bilateral uterine artery embolization with subsequent abdominal myomectomy to treat unchanged regular heavy menstrual flow.

MAIN OUTCOME MEASURE(S)

Ovarian function.

RESULT(S)

Because medical therapy failed to control her menorrhagia, the patient proceeded with uterine artery embolization. She had persistent menorrhagia after bilateral uterine artery embolization and underwent exploratory laparotomy and myomectomy. After surgery, she had amenorrhea, hot flushes, and elevated FSH levels for 3 months. Ovarian function recovered after a short course of oral contraceptives, and the patient conceived without assistance.

CONCLUSION(S)

Several interventions can affect normal ovarian function and can lead to permanent or transient ovarian failure. Possible causes of transient ovarian failure are radioactive iodine treatment, radiation, chemotherapy, pelvic surgery, stress, and uterine artery embolization. Before these interventions are applied, the possibility of ovarian failure and available preventive measures should be discussed with the patient.

Intratumoral aromatase in human breast, endometrial, and ovarian malignancies

In human estrogen-dependent neoplasms such as breast, endometrioid endometrial, and surface epithelial-stromal ovarian carcinomas, intratumoral aromatase is considered to play important roles in converting circulating androgens derived from adrenal cortex and/or ovary to estrogens, possibly in association with 17 beta-HSD type 1 and estrogen sulfatase. Analysis of intratumoral aromatase in these estrogen-dependent neoplasms is important not only in understanding the development and biological behavior of these tumors, but also in the clinical management of these patients, because suppression of intratumoral aromatase by newly developed aromatase inhibitors may provide new potentials in endocrine therapy of these patients.

Triptorelin acetate administration in early pregnancy: case reports and review of the literature

When using a long protocol with cycle day 23 gonadotrophin-releasing hormone agonists (GnRH-a) administration, an elevated estradiol level or a missed period 10-14 days after initiating pituitary downregulation should alert the physician to the possibility of a pregnancy. We report 4 pregnancies occurring during pituitary downregulation with Triptorelin acetate in 366 in-vitro fertilization (IVF) cycles resulting in 3 deliveries of 4 normal neonates at term and 1 first trimester abortion. This supports published data reporting a 1% spontaneous pregnancy incidence in women undergoing pituitary desensitization GnRH-a during the luteal phase prior to planned IVF treatment, a 15.9% abortion rate and a 1.7% malformation rate. Our cases together with other published data suggest that pregnancy outcome is not adversely affected by GnRH-a administration during the luteal phase of the conception cycle. However, long term follow-up of these babies is still lacking and the number of reported cases is too small adequately to rule out the possibility of any detrimental effect related GnRH-a administration in pregnancy.

Immunohistological localization and expression of alpha-actin in the baboon (Papio anubis) corpus luteum

We have recently shown the presence of E-cadherin and of alpha- and gamma-catenins in human and baboon corpora lutea. These are components of adherens junctions between cells. The cytoplasmic catenins link the cell membrane-associated cadherins to the actin-based cytoskeleton. This interaction is necessary for the functional activity of the E-cadherins. Our aim therefore was to determine the presence of alpha-actin in the baboon corpus luteum, to further establish whether the necessary components for E-cadherin activity are present in this tissue. An antibody specific for the smooth muscle isoform of actin, alpha-actin, was used for these studies. The results using immunohistochemistry show that (a) alpha-actin is present in steroidogenic cells of the active corpus luteum, theca externa of the corpus luteum, cells of the vasculature, and the tunica albuginea surrounding the ovary. The intensity of immunoreactivity for alpha-actin varied, with the cells of the vasculature reacting more intensely than the luteal cells. A difference in intensity of immunoreactivity was also observed among the luteal cells, with the inner granulosa cells showing stronger immunoreactivity than the peripheral theca lutein cells. There was no detectable immunoreactivity in the steroidogenic cells of the atretic corpus luteum. However, in both the active and atretic corpora lutea, alpha-actin-positive vascular cells were dispersed within the tissue. (b) Total alpha-actin (luteal and non-luteal), as determined by Western blot analyses, does not change during the luteal phase and subsequent corpus luteum demise (atretic corpora lutea). (c) hCG stimulated the expression of alpha-actin and progesterone secretion by the early luteal phase (LH surge + 1-5 days) and mid-luteal phase (LH surge + 6-10 days) cells in culture, but only progesterone in the late luteal phase (LH surge + 11-15 days). The data show that alpha-actin is present in luteal cells and that its expression is regulated by hCG, thus suggesting that E-cadherin may form functional adherens junctions in the corpus luteum.

Progesterone profiles in luteal-phase defects associated with recurrent spontaneous abortions

PURPOSE

Histologically documented luteal-phase defects (LPD) have been detected in 20-40% of women with recurrent spontaneous abortions. In 28 patients with recurrent spontaneous abortions, luteal-phase serum progesterone (P) levels (days 19, 21, 23, 25) and endometrial biopsies were evaluated.

METHODS

On the basis of endometrial biopsy findings, the patients were separated into two groups: Group 1, recurrent spontaneous abortions with LPDs (n = 18); and Group 2, recurrent spontaneous abortions with normal biopsies (n = 7). The data are shown in the table below.

CONCLUSIONS

This study demonstrated that the P values found in Group 1 were significantly lower than those in Group 2, almost throughout the luteal phase. The results also indicate a close relationship between the P profile in the luteal phase and endometrial biopsy.

Disturbance of follicular development and endocrine reactions induced by the antiovulatory effective progesterone antagonist Onapristone

The present study was undertaken to investigate whether inhibition of ovulation, which is known to occur after treatment with progesterone antagonists, is due to the effect of high levels of prolactin. Therefore, rats with 4-day cycles were treated with the antiprogestin, Onapristone (ON), once daily starting on the evening of estrus. It was detected that the profile of peripheral prolactin levels during the treatment with ON was not remarkably different from that found in the controls. Furthermore, bromocriptine, a prolactin antagonist, was not able to reverse the antiovulatory potency of ON. It is concluded that the antiovulatory effect of ON might not be related to changes in the level of prolactin. Nevertheless, prolactin levels remained high after the preovulatory surge. Thus, we cannot exclude the possibility that PRL plays a role in the induction of anovulatory cycles observed during long term treatment. In animals treated for the length of one cycle we found that the preovulatory LH surge decreased but it remains questionable whether this contributes to the inhibition of ovulation by ON. Interestingly, basal LH, androgen and estrogen levels were elevated. Accordingly, we favour the idea that LH stimulates the theca interstitial cells to produce excessive amounts of androgens which may be aromatized into estrogens. These high levels of androgens and estrogens may contribute to the antiovulatory mechanism of ON by disturbing physiological follicular development. In fact, a morphometrical analysis revealed an increase in the volume density of late tertiary follicles. The increased progesterone levels may also be related to high basal LH levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Increasing progesterone secretion and 3 beta-hydroxysteroid dehydrogenase activity of human cumulus cells and granulosa-lutein cells concurrent with successful fertilization of the corresponding oocyte

In many studies it has been documented that the induction of multiple follicular growth in humans results in an asynchrony between the degree of cumulus mucification, oocyte meiotic maturation, fertilizability, and follicular cell progesterone (P4) secretion. The present study was carried out on oocytes enclosed in fully mucified cumulus. Thus, oocyte fertilizability was correlated to human cumulus cell (hCC) and human granulosa-lutein (G-L) cell competence for P4 secretion in culture. In the G-L cells, P4 secretion and percentage of cells manifesting 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity increased concurrently with the period of culture. In the hCC, however, P4 secretion decreased concurrently with elongation of the culture period, whereas the percentage of 3 beta-HSD-positive cells increased. In hCC corresponding to the fertilized oocytes, P4 accumulation in culture medium was 1.9-fold (P < 0.001) and 1.6-fold (P < 0.02) higher on days 0-3 and 3-5 of culture, respectively, as compared to P4 accumulation in hCC of unfertilized oocytes. Also, in hCC corresponding to the fertilized oocytes, the degree of 3 beta-HSD activity was found to be significantly higher shortly after aspiration and after either 3 or 5 days, compared to hCC of unfertilized oocytes. In the G-L cells pooled from all follicles yielding mature cumulus-oocyte complexes, P4 accumulation and percentage of 3 beta-HSD-positive cells increased concurrently with the increase in percentage of fertilized eggs of each individual woman. These results indicate that in stimulated cycles, follicles yielding mature cumulus-oocyte complex, oocyte fertilizability, and G-L cell or hCC competence for P4 secretion are correlated and synchronous.

Functional pathology of human ovarian steroidogenesis: Normal cycling ovary and steroid-producing neoplasms

In human reproductive endocrinology and pathology, it is important to localize the sites of steroid hormone production to obtain a better understanding of steroid metabolism. Previous approaches, including morphological and biological studies, could not sufficiently demonstrate which cells produce what steroids in both normal and pathological human ovaries. Recent development of immunohistochemistry and in situ hybridization of the enzymes specifically involved in sex steroid biosynthesis made it possible to detect the expression of steroidogenic enzymes, and subsequently the sites of specific steroid production in diagnostic pathology materials. There are, however, some limitations in the approaches, including correlation of the findings with preoperative systemic hormonal manifestations in the patients with sex cord-stromal tumors of the ovary, and great care should be taken when interpreting results.

Temporal and spatial localization of steroidogenic enzymes in premenopausal human ovaries: in situ hybridization and immunohistochemical study

In situ hybridization and immunohistochemical localization of cytochrome P450 cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), cytochrome P450 17 alpha-hydroxylase (P450c17) and cytochrome P450 aromatase (P450arom) was performed in 50 morphologically normal human premenopausal ovaries, and correlated these findings with their endometrial phase. In general, mRNA expression of these enzymes examined by in situ hybridization were in good agreement with immunolocalization examined by immunohistochemistry. Expression of P450scc, 3 beta HSD and P450c17 was observed in large-sized preantral follicles, consisting of more than five layers of granulosa cells, preovulatory follicles, corpora lutea, and some degenerating corpora lutea and atretic follicles in all endometrial phases. Several follicles and/or corpora lutea positive for these enzymes were observed in the same ovary. Expression of P450arom was generally observed in only one follicle (antral or preovulatory follicle) or corpus luteum per case in mid proliferative to premenstrual phase, and was not observed in menstrual to early proliferative phase. These findings indicated that (1) expression of steroidogenic enzymes was associated with the continual human ovarian process including follicular development and atresia, and (2) especially, P450arom expression may occur only in a selected antral follicle and may have an important role in dominant follicular development.

Gonadotropin and ovarian hormone dynamics in luteal phase defects

Blood samples were obtained during early follicular, periovulatory, and luteal phases in four women with out-of-phase endometrial biopsy specimens and four normal controls. In the study cycle, follicular development was evaluated and a late luteal phase endometrial biopsy was performed in each subject. Area under the luteal phase progesterone curve positively correlated with degree of maturity of the endometrial biopsy. Peak serum estradiol, maximum follicular diameter, and both immunoactivity and bioactivity of the preovulatory luteinizing hormone and follicle-stimulating hormone surges were similar in the luteal phase defect cycles as compared with normal cycles. Likewise luteinizing hormone bioactivity in the luteal phase of the luteal phase defect cycles was similar to that of normals. These data show that the immunoactivity and bioactivity of periovulatory and luteal phase gonadotropins may be normal in luteal phase defect cycles.