Mid-menstrual Cycle Research Articles

Ovarian prorenin.

We review here recent evidence that the ovaries synthesize and secrete prorenin and we explore the possible reasons why prorenin, and not active renin, is formed almost exclusively in this extra-renal site. Very high concentrations of prorenin are present in the human ovary in the fluid inside mature follicles. This ovarian prorenin appears to be secreted into the circulation since plasma prorenin increases in normal women for two to three days at mid-menstrual cycle, at the time of ovulation. No change in plasma active renin occurs at this time. Plasma prorenin increases much more at mid-cycle in women whose ovaries have been hyperstimulated with gonadotropins. Their mid-cycle increment in plasma prorenin (after hCG) is directly related to the number of ovarian follicles. Plasma prorenin also increases markedly (10-fold) in pregnant women within two weeks after conception, in parallel with the rise in endogenous hCG. The ovaries are the apparent source of the increase in plasma prorenin during pregnancy since no such increase occurred in a woman with ovarian failure who conceived after receiving a donor egg. These results suggest that the ovaries synthesize and secrete prorenin in response to stimulation by gonadotropic hormones. Future studies will investigate the potential role of ovarian prorenin in human reproductive function. We postulate the existence of a prorenin receptor which activates prorenin and, in consequence, activates a local renin-angiotensin system. The functioning of this system may be regulated by changes in prorenin and its receptor.

Propranolol pharmacokinetics during the menstrual cycle.

The pharmacokinetics of propranolol during menstruation and in the mid menstrual cycle have been studied in nine young women taking a single 80 mg tablet on each occasion. There were wide between-individual differences in the serum concentration at any given time (4-5 fold at peak concentrations) but the serum concentration time curves within individuals showed only mild variations. The differences between the average pharmacokinetic parameter estimates for the group did not differ significantly between the two periods of study.

Do particles translocate from the vagina to the oviducts and beyond?

To investigate whether particles deposited in the vagina translocate to the oviducts, 0.3 ml of a 4% bone black suspension was deposited in the posterior vaginal fornix of each of five cynomolgus monkeys ( Macaca fascicularis) during their mid-menstrual cycle. Simultaneously, each animal received 10 units of oxytocin by intramuscular injection. The oviducts of three animals were removed 1 hr after administration of the bone black, while those of the remaining two animals were removed 72 hr after dosing. The removed oviducts were flushed with Hank's solution and then with collagenase solution. The solutions were collected in clean vials and filtered. The filters were examined for bone black particles by light microscopy, as were filters through which solution blanks (negative controls) had been passed. Particles resembling bone black were found on all filters. There were no appreciable differences in the numbers or shape of these particles between the solution-blank filters and the oviduct-flush filters. The particles on both the solution-blank filters and on the oviduct-flush filters probably originated from environmental contamination by ubiquitous carbon particles. While these results suggested that no translocation took place, translocation could not be ruled out with certainty in the absence of quantitative analyses. A more definitive pilot study was then conducted with two dosed monkeys and one control, using talc labelled by neutron activation to circumvent the problem of environmental contamination. γ-Ray analysis of tissue and peritoneal lavage samples for the radionuclides 46Sc, 59Fe and 60Co indicated that no measurable quantities (i.e. > 0.5 μg) of talc translocated from the deposition site in the vagina to the uterine cavity and beyond.

Episodic secretory patterns of immunoreactive luteinizing hormone-releasing hormone (IR-LH-RH) in the systemic circulation of normal women throughout the menstrual cycle

Using established radioimmunoassays for measuring plasma luteinizing hormone-releasing hormone (LH-RH) and serum gonadotropins, we studied the secretory dynamics of these hormones in eight normal ovulatory women during different phases of their menstrual cycle. All of the women demonstrated evidence of pulsatile immunoreactive LH-RH (IR-LH-RH) release throughout the cycle, with IR-LH-RH concentrations fluctuating between 0.5 and 35 pg/ml in the systemic circulation. Analysis of IR-LH-RH episodic secretions revealed a significant increase of both mean IR-LH-RH concentrations (P less than 0.001) and pulse frequency (P less than 0.05) during the periovulatory period. Furthermore, plasma IR-LH-RH titers in five normal women studied during the morning and night at mid-menstrual cycle fluctuated markedly, with slightly greater episodic discharges observed during the night than in the morning (P less than 0.05) and no significant change in pulse frequency.

The influence of oral contraceptives on the metabolism of methaqualone in man.

1 Oral contraceptives were shown to suppress the mid-cycle increase in methaqualone metabolism observed in premenopausal women not receiving oral contraceptive therapy. No women were identified in whom this suppression was not observed. 2 Combined oestrogen-progestogen contraceptives produced the effect in all nine women studied. The effect was also observed in one woman who was receiving progestogen-only contraceptives. 3 The effect of the combined contraceptives was observed within one month of the commencement of the contraceptive therapy. 4 The results emphasise the need to monitor the effect of the menstrual cycle in women not receiving oral contraceptive therapy when the effects of such therapy is studied. 5 These effects are more likely to be the consequence of an inhibition of hormonal control of hepatic metabolic activity by the synthetic steroids than they are to simple inhibition of hepatic metabolism.

Temperature and heat flow variations during the menstrual cycle: Breasts and extremeties

1. 1. The mid-menstrual cycle breast temperature ( T Br) peak in women earlier described by Nassar & Smith (1975) has been more closely evaluated and compared with menstrual cycle variations in other peripheral regions. 2. 2. Alignment of the T Br, heat flow and conductance data by the day of the T Br peak showed a significant rise and fall in these three variables, the peak occurring 2–4 days prior to the estimated day of ovulation and the nadir usually within 1 day of estimated ovulation. The relative changes in these data during the mid-cycle peak proved significant and distinguished it from other cyclic variations or elevations later in the cycle. This phenomenon was not found to occur at peripheral areas of the arm, thigh, calves and forehead. 3. 3. Rectal temperature ( T Re) remained stable at the time of the T Br peak, with a slight elevation following estimated ovulation. 4. 4. Progesterone assays clearly indicated the occurrence of ovulation in 70% of the subjects studied. 5. 5. It is noted that the T Br pattern very closely resembles that of plasma oestradiol levels established for humans during the menstrual cycle, and it is hypothesized that the breast thermal response is due to cyclic changes in oestrogen levels leading to an increase in blood flow to that area.

Influence of environmental chemicals on drug therapy in humans: studies with contraceptive steroids.

The effects have been studied of various environmental factors on the variability in response to oral contraceptive steroid therapy in women. Ten- to thirty-fold variations in plasma concentrations of norethisterone, L-norgestrel and ethinyloestradiol have been shown in samples taken 12 h after administration of oral contraceptives in mid-menstrual cycle. Factors shown to be responsible for this variation include passage into the enterohepatic circulation, a variable first-pass effect, and changes in metabolism in the gut wall or liver due to diet, disease, smoking or administration of drugs. Phenobarbitone and the antibiotic rifampicin increase both oestrogen and progestogen metabolism in women and in experimental animals by increasing hepatic and gut wall metabolism. In animals, other antibiotics (ampicillin, neomycin and lincomycin) suppress the gut flora that normally hydrolyse steroid conjugates excreted in bile; enterohepatic circulation or oral contraceptive steroids is thus reduced and their plasma concentrations lowered by up to 90%. In the human, ampicillin has a variable but less dramatic effect on elimination of oral contraceptives. Samples of gut wall mucosa obtained from patients with coeliac disease are defective in their ability to metabolize oral contraceptives. Cigarette smokers eliminate ethinyloestradiol more rapidly than non-smokers; an increased production of reactive steroid metabolites may thus be a cause of vascular disease in women who smoke and take contraceptive steroids.

Mittelschmerz. Sonographic demonstration

Ultrasonography of the pelvis at mid-menstrual cycle in normal women has demonstrated small quantities of free fluid in 40% of cycles. Two thirds of the cycles associated with pain had ultrasonically demonstrated fluid at ovulation. These sonographic findings at Mittelschmerz confirm the physiological trauma of ovulation.

Lack of fluctuation in growth hormone secretion during early sleep in early and midmenstrual cycle.

ABSTRACT To evaluate the influence of varying estrogen levels on nocturnal growth hormone (GH) secretion, sleep-induced GH secretion was evaluated in 5 women at midcycle and during the period of active menstrual bleeding. GH secretion varied from woman to woman, but no consistent difference in GH secretion was observed at different times of the menstrual cycle. The data show that nocturnal GH secretion is not altered by physiologic variations of estrogen levels.

Episodic release of luteinizing hormone at mid-menstrual cycle in normal adult women.

Twelve normal women with regularly recurring menstrual periods had electrophysiological recording performed and indwelling venous catheters inserted during 1–4 consecutive nights of sleep at mid-menstrual cycle. Four of these subjects were also studied during daytime waking activity. Plasma samples were collected at frequent intervals in order to study the temporal aspects of LH secretion. LH was measured by double-antibody radioimmunoassay. All subjects demonstrated episodic secretion of LH at a frequency (for major episodes) which resembled that of the human REM-non-REM sleep cycle. However, there was no correlation of plasma LH values with the stages of sleep. In addition, no difference in LH concentration was found between sleep and waking. During the LH surge, episodic secretion of LH continued and was superimposed on a rising baseline. Two subjects, who were studied sequentially before and during the LH surge, demonstrated sudden elevations of plasma LH concentration in the latter part of the sleep ...

Peri-menstrual sexual behavior among rhesus monkeys.

During a behavioral study of free-ranging rhesus monkeys, non-pregnant females were observed to show sexual behavior both at mid-menstrual cycle and peri-menstrually. The basis of the dual estrous periods appears to be dual maxima in estrogen secretion. Peri-menstrual estrus may be an evolutionary vestige from a tupaiid-type sexual cycle. The occurrence of sexual behavior proximal to menstruation forces a redefinition of the term ‛es-trus.’