Endometrial glandular proliferation and estrogen receptor content during the normal menstrual cycle

The 5' untranslated region of an RNA molecule is thought to play an important role in the regulation of translation. Following a recent report that a single nucleotide is sufficient to act in this role in the unicellular organism Giardia, we show that this is also the case for a mammalian in vitro system. These results also demonstrate that an RNA can initiate translation from a start codon where an ideal translational consensus sequence is impossible.     

Serum levels of the pregnancy zone protein during the normal menstrual cycle

pregnancy zone protein (PZ), low polar estrogen, progesteorne, luteinizing hormone, and follicle stimulating hormone levels during normal menstrual cycles were studied. Serum samples were taken from 12 healthy women of different ages throughout their menstrual cycle. PZ levels showed no significant pattern and no statistically significant association was shown between PZ levels and any of the hormones. PZ levels were higher in older women and varied within each women's cycle. The study results indicate that peak estrogen levels during the menstrual cycle are not sufficient in duration or magnitude to cause increased serum levels of PZ.     

Sleep and the menstrual cycle.

To evaluate changes in sleep across the phases of the menstrual cycle, sleep-wake diaries were completed by 32 healthy women twice daily for 2 menstrual cycles. There was a significant increase in sleep onset latency and a significant decrease in sleep efficiency and sleep quality during the luteal phase. This increase in sleep disturbance was observed in the entire sample and was not related to the severity of other premenstrual symptoms. However, women having increased severity of other premenstrual symptoms reported greater luteal increase in daytime sleepiness. Thus, although menstruating women are likely to show increased sleep disturbance during the luteal phase, those with other, more severe premenstrual symptoms are more likely to experience a luteal increase in daytime sleepiness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endocrine regulation of the menstrual cycle

Physiological data concerning the serum concentrations and the pituitary content of varian steroids and gonadotropins, respectively, are reviewed. On the basis of these physiological data results from experimental studies are critically evaluated as far as their significance for the understanding of the physiology of the cycle is concerned. Data from the literatur and results from own studies are incorporated in a concept of the endocrine regulation of the human menstrual cycle.     

Women, alcohol and the menstrual cycle

This review presents evidence which implicates a role for menstrual cycle phase in the response of pre-menopausal women to moderate alcohol intake. It is concluded that the majority of published studies have suffered from poor methodological design and have employed inadequate means of cycle phase identification. Contradictory and ill-founded findings have been reported. The best evidence to date suggests that women eliminate alcohol more rapidly during the mid-luteal phase of the cycle. This finding needs to be substantiated by further studies.     

Substrate oxidation at rest and during exercise: effects of menstrual cycle phase and diet composition

The estrogen hormones have been shown to be highly glycogenic as well as lipolytic in nature. It is unknown whether the metabolic actions of estrogens impact upon energy metabolism during exercise. The composition of prior diet, however, does affect exercise energy metabolism. This study examined the influence of menstrual cycle phase (mid-follicular [FP; low estrogen] vs. mid-luteal [LP; high estrogen]) and diet composition on the rate of substrate oxidation for carbohydrate (CHO) and lipid at rest and during various intensities of physical exercise. Nine subjects completed an experimental session under four different menstrual cycle-diet conditions: 1) FP following a 3-day high CHO diet [75% total caloric intake], 2) FP following a 3-day low CHO diet [35% total caloric intake], 3) LP following a 3-day high CHO diet, and 4) LP following a 3-day low CHO diet. In each of the experimental sessions substrate oxidation was determined at rest and during cycle ergometer exercise at intensities of 30, 50, and 70% VO2max, respectively. Statistically significant (p < 0.05) interaction effects on substrate oxidation due to the menstrual cycle phase and diet conditions were found at rest and during 30%-50% exercise. In general, CHO oxidation was lowest and lipid oxidation highest in the LP under a low CHO diet condition.     

The regulation mechanism of the female menstrual cycle

The hormonal patterns during menstrual cycle, which consist of cyclic alterations in gonadotropins, estradiol, and progesterone, are controlled by hypothalamic-pituitary-ovarian feedback mechanism. GnRH produced in hypothalamus acts on the pituitary cells to secrete FSH and LH, which stimulate the follicular development. The developed follicles secrete estradiol, progesterone, inhibin, activin, and follistatin. Estradiol and progesterone, at different concentrations and/or ratios, either positively or negatively control the feedback of hypothalamic-pituitary axis in regulating the secretion of GnRH, FSH and LH. Inhibin and follistatin selectively suppress, whereas activin enhances the secretion of FSH in the pituitary. Recently, various additional factors produced by the ovary have been identified to contribute to the follicular development by paracrine and/or autocrine regulation as well as to feedback on hypothalamic-pituitary unit.     

Tobacco withdrawal in women and menstrual cycle phase.

Because negative mood is a characteristic of both tobacco withdrawal and menstrual discomfort, withdrawal may vary by menstrual cycle phase. Tobacco withdrawal, mood, and menstrual discomfort were assessed in premenopausal women who quit smoking during either the follicular (Days 1–14 postmenstrual onset; n?=?41) or luteal (Day 15 or longer postmenstrual onset; n?=?37) phase of the menstrual cycle and maintained biochemically verified smoking abstinence during the postquit week. Women quitting during the luteal phase reported significantly greater increases in tobacco withdrawal and self-reported depressive symptoms than women quitting during the follicular phase. These results indicate that selecting a quit-smoking day early in the follicular phase may attenuate withdrawal and negative affect in premenopausal female smokers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of the menstrual cycle on dressing behavior in the cold

The purpose of the present study was to determine the effect of the menstrual cycle on dressing behavior in cold exposure. Rectal and skin temperatures, temperature sensation and metabolic rate were measured in seven women during the luteal (L) and the follicular (F) phases of the menstrual cycle, as was their dressing behavior in these two phases. The subjects were instructed to dress so as to feel comfortable when the ambient temperature was decreased from 30 degrees C to 15 degrees C (07:00-09:00). Most subjects dressed more quickly and with thicker clothing in the L phase. They felt cooler in the L phase during the last 30 min of the temperature fall. Rectal and skin temperatures showed significant differences between L and F phases and metabolic rate was significantly higher in the L phase. The results can be interpreted in terms of the establishment of a higher set-point in core temperature during the L phase.     

Changes in cognitive task performance across the menstrual cycle.

Examined the effect on cognitive tests of menstrual-cycle-related changes in estrogen in 87 undergraduates. The estrogen peak was expected to facilitate performance of 4 "automatized" tasks and to impair performance of "perceptual-restructuring" tasks, compared with performance in the postovulatory phase when progesterone is thought to counteract the action of estrogen. Daily basal body temperature (BBT) records suggested that 21 Ss did not ovulate in the cycle(s) studied. No main effect of Day 10 of the cycle vs Day 20 occurred for any task in the 66 Ss who did appear to ovulate. However, the magnitude of predicted shifts in performance was significantly correlated with proximity of the "Day 10" testing day to the lowest BBT, the presumed preovulatory estrogen peak; and to the "Day 20" proximity to the highest BBT, the presumed progesterone peak. Ss tested 3 or fewer days before the thermal nadir and on or after the thermal peak had the predicted significant changes on 3 of the 4 tasks. Results support the hypotheses and indicate that precise timing is essential to demonstrate the phenomena. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of post-coital contraceptive methods on the endometrium and the menstrual cycle

STUDY OBJECTIVE: To evaluate the effect of treatment with ethinylesteradiol-levonorgestrel or danazol on ovarian function, gonadotrophin release and endometrial development during the time when a pregnancy may occur following unprotected intercourse. METHODS: Women with regular menstrual cycles were followed during one control, one treatment and one follow-up month. The women obtained either a combination of 0.5 mg levonorgestrel and 0.1 mg ethinylestradiol (Yuzpe regimen: n = 16) or 600 mg danazol orally and repeated after 12 hours (n = 16). The treatment was administered on either cycle day (cd) 12 or day LH +2. An endometrial biopsy was obtained once on cd LH +6 to +8 in the subjects treated on cd LH +2 both in control and treatment cycles, and morphometric analysis was performed. The concentrations of LH, pregnandiol (P2G), and estrone (EIG) glucuronide were followed daily in morning urine during control and treatment cycles. RESULTS: Following treatment with the Yuzpe regimen on cd 12 the LH surge was either undetectable (three subjects), postponed to cd 16 to 22 (three subjects) or cd 38 to 39 (two subjects) with lower P2G and LH levels than in the control cycle. Following preovulatory treatment with danazol, no LH peak could be detected in four subjects and in the remaining four subjects the LH peak varied between cd 13 and cd 24. The mean area under the curve for LH was significantly lower, the levels of EIG were slightly higher and the P2G levels were unaffected in comparison with the control cycle. Neither of the two treatments administered on cd LH +2 affected the hormonal pattern and only a discreet effect on the development of the endometrium was seen after the EE/LNG treatment. CONCLUSION: The findings indicate that the contraceptive effect of postcoital treatment with EE/LNG and danazol is mainly due to an inhibition or delay of ovulation and insufficient corpus luteum function. The direct effect on the endometrium is limited, if any.     

Immunolocalization of inhibin and activin subunits in human endometrium across the menstrual cycle

Inhibin/activin alphaC/alphaN and betaA subunits were localized immunohistochemically in the human endometrium throughout the menstrual cycle using an affinity-purified sheep polyclonal antibody raised against the alphaC/alphaN subunit and an affinity-purified rabbit polyclonal antibody raised against the betaA subunit. The betaB subunit was below the level of detection in all human endometrial samples tested. Immunoreactive inhibin alphaC/alphaN subunit was localized in the luminal epithelium, glandular epithelium, stromal tissues and vascular endothelium with no significant variation across the normal menstrual cycle. Immunoreactive betaA subunit, common to inhibin A and activins AA and AB was localized in the luminal and glandular epithelium and in migratory cells while the endometrial stromal cells, decidua, vascular smooth muscle and endothelium were devoid of immunoreactivity. A significant variation of immunoreactive betaA subunit was observed in glandular and luminal epithelium across the normal menstrual cycle. In proliferative endometrium, only a very low level of betaA immunostaining was seen in luminal and glandular epithelium, while the luminal epithelial staining increased significantly in the early secretory phase and remained relatively constant over the rest of the menstrual cycle. A progressive increase in betaA immunoreactivity was observed also in the glandular epithelium during the secretory phase reaching a maximum in the late secretory phases, and decreasing at menstruation. Co-localization studies on serial sections suggested that the migratory cells expressing strong betaA immunoreactivity were macrophages and neutrophils but not eosinophils or mast cells. Thus, cells within the human endometrium are capable of expressing inhibin/activin molecules in vivo. The variation in the pattern of secretion of the betaA subunit across the menstrual cycle suggests that activin peptides may have a physiological role in endometrial function.     

The timing of breast cancer surgery during the menstrual cycle

A number of recent studies have suggested that survival among premenopausal women after primary treatment of breast cancer may be affected by the estimated hormonal milieu at the time of surgery, especially in those with axillary lymph node metastases. The concept has created considerable controversy and has resulted in the publication of many negative reports. However, several biological mechanisms have been suggested for the observed survival advantage. These include cyclical patterns of immune function, as well as cell division and cell death, that correlate with hormonal fluctuations of the menstrual cycle. Comparisons among studies of timing have been complicated by differences in menstrual cycle divisions, variability in the sources of study populations, limited availability of menstrual history data, and changes over the past 2 decades in primary and adjuvant breast cancer therapy. Several recent publications have been enhanced by the availability of serum collected at the time of surgery that enables accurate measurement of the hormonal milieu. In these studies, the likelihood of misclassification by menstrual cycle phase is reduced, and dependence on recalled menstrual history is eliminated. High progesterone levels have been associated with improved survival. These findings have encouraged some to suggest that perioperative administration of progesterone or tamoxifen (Nolvadex) may provide a preventive avenue comparable to scheduling surgery during the luteal phase. Further multidisciplinary studies are needed, however, to clarify the influence of the naturally occurring or medically induced hormonal milieu at the time of breast cancer surgery on survival in premenopausal women.     

Ethnic differences in the length of the menstrual cycle during the postmenarcheal period

In 1989, 125 African-American and 123 European-American girls aged 12-14 years were enrolled in a 2-year study in which they maintained a menstrual calendar, recording the date and amount of menstrual bleeding. Weight, exercise, and stress during the previous week were recorded at the start of each menstrual cycle. Although only minor ethnic differences were observed in expected cycle length (29.3 vs. 28.8 days for European-American and African-American girls, respectively), more prominent differences were observed in the between-subjects standard deviation of cycle length (2.9 vs. 2.2 days, respectively) and in the odds of having a cycle longer than 45 days (odds ratio=1.86, 95% confidence interval 1.17-2.97) for European-American compared with African-American girls. Low weight for height and high levels of exercise increased the probability of having a cycle longer than 45 days and decreased expected cycle length of 13- to 45-day cycles. Additional investigation of potential ethnic differences in menstrual cycle characteristics is warranted.