Ovarian hormones and sexual behavior in Macaca nemestrina.

Determined the concentrations of the ovarian steroids, estradiol and progesterone, in the systemic plasma of 8 female pigtailed macaques and the correlations with sexual behavior and measurements of perineal swelling during the intermenstrual period. Estradiol peaked the day before maximum swelling of the perineum at the end of the 20.7-day follicular phase. Maximum titers of progesterone were recorded during the middle of the 15.1-day luteal phase. None of the female sexual behaviors changed significantly during the ovarian cycle, although intromission rate and frequency of ejaculation by 7 males were higher during the follicular phase. The pattern of ovarian hormone secretion and copulation throughout the menstrual cycle was more like that reported for women than for other mammalian species. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correlation between menstrual cycle and cognitive performance in a chimpanzee (Pan troglodytes).

Extensive research on human subjects has tried to investigate whether there is a correlation between cognitive performance and the menstrual cycle. Less is known about the relationship between the menstrual cycle and task performance in other cognitive animals. We test whether the secretion of a sex hormone [luteinizing hormone(LH)] influences the performance of cognitive tasks by a female chimpanzee (Pan troglodytes) who is part of a long-term cognition research program. We focus on two cognitive tasks: an “easy task,” which consists of simple numerical ordering, and a “difficult task,” which combines numerical ordering with memorizing the numerals' spatial location. Data on the performance of these cognitive tasks, urine samples, and sexual swelling over six menstrual cycles showed that the chimpanzee's performance accuracy decreased and that the intertrial interval was longer during the LH-surge of the menstrual cycle, but only for the performance of the difficult task. These performance attributes seem to reflect a decrease in attention or motivation during ovulation. In summary, the cognitive performance of a chimpanzee was disturbed by hormonal changes despite her long-term experience in the tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Cyclic changes in genital organs and vaginal cytology in cynomolgus monkeys (Macaca fascicularis)

Vaginal cytology was evaluated weekly over 12 months in 20 adult female Cynomolgus monkeys (Macaca fascicularis). After sacrifice of the animals the histology of the ovaries, uterus and vagina were studied in different phases of the menstrual cycle. The cytological examination of the vaginal smears showed that the superficial cells increased in number towards the middle of the cycle and the number of intermediate cells declined gradually. Parabasal cells were observed mainly at the beginning of the cycle; they disappeared towards the middle of the menstrual cycle. During the early follicular phase, the cells were moderately separated from each other, and during the second half of the proliferative or follicular phase, the superficial cells appeared clumped together. Leucocytes were usually absent except for at the beginning of the cycle and in the last few days of the late secretory or luteal phase. The maturation index of the vaginal smears can be considered as a tool for distinguishing the different phases of the menstrual cycle. The microscopic examination of the genital organs showed that during the proliferative or follicular phase of the cycle, which corresponds to the development of the ovarian follicles, the uterus showed growth of endometrial glands, stroma and endothelial cell proliferation with capillary sprouts. Shortly after ovulation and parallel to the formation of the corpora lutea, the endometrium enters the secretory or luteal phase, which is characterized by coiling of endometrial glands, glandular secretion and the differentiation of the spiral artery. The most striking changes in the vagina, is the marked basal cell proliferation and thickening of the stratum granulosum during the follicular phase of the menstrual cycle. The histological changes observed in the vagina demonstrated a good correlation with the observation on cytological examination of the smears. The present study demonstrated that the process of angiogenesis in the uterus during the different phases of the menstrual cycle is a multiple phenomenon involving proliferation, maturation and differentiation.     

Ambulatory blood pressure changes in the menstrual cycle of hypertensive women. Significance of plasma renin activity values

Blood pressure (BP) changes during the menstrual cycle (MC) have not been studied in hypertensive women in relationship to changes in sex hormone levels and plasma renin activity (PRA). We therefore carried out 24 h ambulatory BP recordings and hormonal measurements in 34 hypertensive and 27 matched normotensive women during the follicular ovulatory and luteal phases of the menstrual cycle. Plasma renin activity was similar in the two groups and rose significantly during the luteal phase only in the hypertensives (P < .01). There were no differences in plasma estradiol or progesterone between the normotensives and hypertensives, but testosterone was higher in the hypertensives during the ovulatory (P < .01) and luteal (P < .001) phases. Blood pressure did not change in the normotensives throughout the cycle, but it increased in the hypertensives during ovulation (P < .01). When patients were divided according to mean menstrual cycle PRA, only those with relatively low PRA (< 2 ng/mL/h) had a significant BP rise during ovulation and it primarily occurred at night (P < .05). The results demonstrate that premenopausal hypertensive women have increased testosterone during ovulation and increased testosterone and PRA during the luteal phase of the cycle. Like normotensives, hypertensives with relatively high PRA exhibit no change in BP during the cycle, whereas those with relatively low PRA have a nighttime increase in BP during ovulation.     

Plasma testosterone and dihydrotestosterone in ovulatory and anovulatory cycles

Daily plasma testosterone (T) and dihydrotestosterone (DHT) as well as plasma lueteinizing hormone, plasma estradiol (E2) and plasma progestrone (P) were measured by radioimmunoassay in seven ovulatory cycles and in three anovulatory cycles. In ovulatory cycles, plasma T ranged from 110 to 637 pg. per milliliter, while plasma DNT ranged from 10 to 246 pg. per milliliter. There is an increase in the mean plasma T during the early follicular phase of the cycle with a fall on the day of ovulation. Plasma T levels rise again during the early luteal phase and drop during the late luteal phase of the cycle. Plasma E2 rises during the follicular phase with a preovulatory surge followed by a drop after ovulation and a subsequent secondary rise. Plasma P was less than 1 ng. per milliliter during the follicular phase and increased to above 5 ng. per milliliter after ovulation, reaching levels of 20 to 25 ng. per milliliter during the luteal phase. In anovulatory cycles, there is random fluctuation with no well-defined patterns. Plasma P remained below 1 ng. per milliliter throughout the cycle. The finding of maximum T levels prior to midcycle may reflect increased T production by the ovaries in response to increasing levels of follicle-stimulating hormone. There is little fluctuation in the levels of T during the menstrual cycle. These findings obviate the need for multiple plasma T estimations in the assessment of women with hirsutism, polycystic ovarian disease, and the testicular feminization syndrome.     

Sex hormones affect spatial abilities during the menstrual cycle.

The aim of this study was (a) to show that different measures of spatial cognition are modulated by the menstrual cycle and (b) to analyze which steroid is responsible for these cognitive alterations. The authors collected blood samples in 3-day intervals over 6 weeks from 12 young women with a regular menstrual cycle to analyze concentrations of estradiol, progesterone, testosterone, luteinizing hormone, and follicle-stimulating hormone. The performance on 3 spatial tests was measured during the menstrual and the midluteal phases. A significant cycle difference in spatial ability as tested by the Mental Rotation Test was found, with high scores during the menstrual phase and low scores during the midluteal phase. Testosterone had a strong and positive influence on mental rotation performance, whereas estradiol had a negative one. These results clearly indicate that testosterone and estradiol are able to modulate spatial cognition during the menstrual cycle. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in urologist and patient assessments of health related quality of life in men with prostate cancer: results of the CaPSURE database

Premenstrual syndrome (PMS) is characterized by distressing somatic and behavioral symptoms that develop after ovulation, reach a maximum during the premenstrual days, and disappear within 4 days after the onset of menstruation. Corpus luteum formation is necessary for the presence of symptoms, but the role of luteal hormones is unclear. The aim of this work was to investigate the relationship between sex hormone serum concentrations and premenstrual symptom severity in patients with PMS. Mental and physical symptoms were marked on a validated visual analog scale by 30 PMS patients every evening. Daily blood samples were taken in the luteal phase and in most of the follicular phase. Estradiol, progesterone, FSH, and LH were analyzed. Symptom severity was calculated as the number of negative symptoms expressed per day and as summarized scores of negative ratings. Based on premenstrual hormone concentrations and using the median split method, patients were divided into groups with high and low hormone levels. The pattern of expressed symptoms and summarized scores during the menstrual cycle was similar for the 2 groups. High concentration of luteal-phase estradiol and LH were related to the severity of negative premenstrual symptoms.     

Chronotropic competence in endurance trained heart transplant recipients: heart rate is not a limiting factor for exercise capacity

Soy isoflavones are hypothesized to be responsible for changes in hormone action associated with reduced breast cancer risk. To test this hypothesis, we studied the effects of isoflavone consumption in 14 premenopausal women. Isoflavones were consumed in soy protein powders and provided relative to body weight (control diet, 10 +/- 1.1; low isoflavone diet, 64 +/- 9.2; high isoflavone diet, 128 +/- 16 mg/day) for three menstrual cycles plus 9 days in a randomized cross-over design. During the last 6 weeks of each diet period, plasma was collected every other day for analysis of estrogens, progesterone, LH, and FSH. Diet effects were assessed during each of four distinctly defined menstrual cycle phases. Plasma from the early follicular phase was analyzed for androgens, cortisol, thyroid hormones, insulin, PRL, and sex hormone-binding globulin. The low isoflavone diet decreased LH (P = 0.009) and FSH (P = 0.04) levels during the periovulatory phase. The high isoflavone diet decreased free T3 (P = 0.02) and dehydroepiandrosterone sulfate (P = 0.02) levels during the early follicular phase and estrone levels during the midfollicular phase (P = 0.02). No other significant changes were observed in hormone concentrations or in the length of the menstrual cycle, follicular phase, or luteal phase. Endometrial biopsies performed in the luteal phase of cycle 3 of each diet period revealed no effect of isoflavone consumption on histological dating. These data suggest that effects on plasma hormones and the menstrual cycle are not likely to be the primary mechanisms by which isoflavones may prevent cancer in premenopausal women.     

Cyclic changes of cervical mucus enzymes related to the time of ovulation. I. Alkaline phosphatase

The concentration of alkaline phosphatase in cervical mucus was serially determined during a menstrual cycle in five normal ovulatory women and correlated with the time of ovulation as monitored by the basal body temperature and radioimmunoassay of serum lutenizing hormone (LH), progesterone, and estradiol. The activity of alkaline phosphatase decreased significantly at midcycle just prior to the LH surge and began to rise after ovulation. Self-detection of cervical mucus alkaline phosphatase may provide a practical method of ovulation prediction.     

Clinical investigation of the menstrual cycle. III. Clinical, endometrial, and endocrine aspects of luteal defect

This study was intended to correlate different clinical and biologic parameters to better define luteal insufficiency (LI) and to contribute to a better understanding of its origin. Endometrial patterns were used as the basis for classification of clinical cases. Of 328 outpatients with menstrual disorders and/or infertility, 88 were considered to have LI. Their cycles were compared with 79 normal cycles. Two different principal endometrial patterns of LI are described: pure LI, when the endometrium is more than 2 days out of phase; and LI with persistent estrogenic influence, when the histologic estrogenic stigmata are excessive during the luteal phase. Basal body temperature charts demonstrated menstrual cycle disturbances: either ovulation delay or a slow increase in temperature (longer than 2 days). Plasma steroid concentrations also demonstrated a perturbation of the entire menstrual cycle: progesterone levels were statistically significantly lower in LI than in normal cycles and this defect was worse when the estrogenic influence was persistent; the preovulatory estradiol peak was disturbed in all circumstances, as was the concentration of endometrial steroid receptors. These simultaneous abnormalities strongly suggest a central origin of LI.     

Sex-sensitive tasks in men and women: A search for performance fluctuations across the menstrual cycle.

This study validated 6 cognitive and motor-skill tasks as sex-sensitive and used them to investigate whether women's performance changed across the menstrual cycle. Three putative female-advantage tasks and 3 putative male-advantage tasks were administered twice, at 6-week intervals, to young college women and men. Counterbalanced for order, women received the tests once during menstruation and once during the midluteal phase. The midluteal phase was determined by projection from day of ovulation, as verified by ovulation detection kits, and by confirmation of subsequent menstruation. Results revealed a significant sex difference for 5 of the 6 tasks. However, there was no evidence that performances differed with menstrual cycle phase. These results from younger women, combined with previous results from older women, may help establish the boundaries for hormonal influences on cognitive and motor-skill behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synchronicity of frequently sampled, 24-h concentrations of circulating leptin, luteinizing hormone, and estradiol in healthy women

Leptin, an adipocyte hormone, is a trophic factor for the reproductive system; however, it is still unknown whether there is a dynamic relation between fluctuations in circulating leptin and hypothalamic-pituitary-ovarian (HPO) axis hormones. To test the hypothesis that fluctuations in plasma leptin concentrations are related to the levels of luteinizing hormone (LH) and estradiol, we sampled plasma from six healthy women every 7 min for 24 h during days 8-11 of the menstrual cycle. Cross-correlation analysis throughout the 24-h cycle revealed a relation between release patterns of leptin and LH, with a lag of 42-84 min but no significant cross-correlation between LH and estradiol. The ultradian fluctuations in leptin levels showed pattern synchrony with those of both LH and estradiol as determined by cross-approximate entropy (cross-ApEn). At night, as leptin levels rose to their peak, the pulsatility profiles of LH changed significantly and became synchronous with those of leptin. LH pulses were fewer, of longer duration, higher amplitude, and larger area than during the day. Moreover, the synchronicity of LH and leptin occurred late at night, at which time estradiol and leptin also exhibited significantly stronger pattern coupling than during the day. We propose that leptin may regulate the minute-to-minute oscillations in the levels of LH and estradiol, and that the nocturnal rise in leptin may determine the change in nocturnal LH profile in the mid-to-late follicular phase that precedes ovulation. This may explain the disruption of hypothalamic-pituitary-ovarian function that is characteristic of states of low leptin release, such as anorexia nervosa and cachexia.     

Expression of pS2, c-erbB-2, and cathepsin D during the menstrual cycle in human breast cancers

BACKGROUND: Many studies have addressed the effect of the timing of surgery for breast cancer relative to menstrual cycle phase, with conflicting results. Explanations for the possibility that survival could be altered by the appropriate timing of breast cancer surgery in humans remain speculative. METHODS: We examined the expression of three estrogen related proteins (c-erbB-2, cathepsin D, pS2) in the breast tumors from 69 premenopausal women sampled in different phases of the menstrual cycle. Data on S-phase fraction and hormone receptor expression were also analyzed. Immunohistochemical assays were used to measure the proteins of interest. S-phase fraction was determined by flow cytometry. Analyses were performed based on fraction of cells staining positive for the protein, density of stain, and a histoscore that combined both fraction of positive cells and density. RESULTS: We found no differences in c-erbB-2, cathepsin D, hormone receptor, or S-phase levels in tumors sampled in the follicular versus luteal phase, or perimenstrual versus periovulatory phase. The exception was pS2, which was expressed at greater levels during the luteal than during the follicular phase of the cycle (p < 0.01); but there was no difference in pS2 expression when the patients were classified as periovulatory versus perimenstrual. CONCLUSIONS: Our findings do not support a variation in c-erbB-2, cathepsin D, S-phase fraction, or receptor expression as an explanation for the differences in breast cancer prognosis when surgery is timed by menstrual cycle phase. The finding that pS2 (an indicator of hormone sensitivity, and possibly better prognosis) is expressed at higher levels in tumor samples during the luteal phase suggests that the biologic profile of breast tumors may vary with the menstrual cycle and that these variations deserve further study.     

Impaired steroidogenesis in the luteal phase of the reproductive cycle and during pregnancy in rhesus monkeys immunized with the beta-subunit of ovine luteinizing hormone

Monkeys immunized with the beta-subunit of ovine luteinizing hormone (oLH beta) develop antibodies which cross react with rhesus chorionic gonadotropin (rhCG) and luteinizing hormone (rhLH). Immunization causes shortened menstrual cycles and reduced fertility. Fertility can be restored by administration of medroxyprogesterone acetate (MPA) during the first 5 weeks of pregnancy. In the present study, we have measured the effects of circulating oLH beta-antibodies on peripheral estradiol, progesterone and 17 alpha OH-progesterone (17OH-P) concentrations throughout the menstrual cycle and during gestation in monkeys which became pregnant following MPA-treatment. Progesterone concentrations were markedly reduced during the luteal phase in cycling animals and the luteal phase of the cycle was significantly shorter as compared to non-immunized controls. Concentrations of estradiol and 17OH-P in the peripheral circulation were not affected by the oLH beta-antibodies. In immunized monkeys which became pregnant following MPA-treatment, progesterone and 17OH-P levels were consistently lower and estradiol concentrations were increased during the second and third trimesters. Our results show that circulating antibodies to oLH beta have multiple endocrinological effects. Corpus luteum function is impaired in cycling monkeys and during the early part of pregnancy. In addition, the pattern of steroid secretion remains abnormal in pregnant monkeys even after the luteal-placental shift.     

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)     

ADRF differential cross polarization spectroscopy of synthetic calcium phosphates and bone mineral

BACKGROUND: Gender-dependent differences in cytochrome P450 activity, drug metabolism, drug elimination, and their clinical consequences are increasingly apparent. P450 3A4 is the most abundant P450 isoform in the human liver and is responsible for metabolizing a vast and diverse assortment of therapeutic agents, including opioids, benzodiazepines, and local anesthetics. P450, 3A4 activity is higher in women, influenced by steroid hormone levels, and is speculated to vary during the menstrual cycle. This investigation tested the hypothesis that P450 3A4 activity varies during the menstrual cycle. Alfentanil clearance was used as a metabolic probe for P450 3A4 activity. METHODS: Alfentanil (20 micrograms/kg bolus) was administered to nine nonsmoking, nonpregnant female volunteers (age, 26 +/- 5 yr) with normal menstrual cycles on three separate occasions during the same menstrual cycle: days 2 (menstrual phase), 13 (estrogen peak), and 21 (progesterone peak). Venous plasma alfentanil concentrations were determined by gas chromatography-mass spectrometry. Alfentanil clearance was determined by noncompartmental methods and by a three-compartment model with both pooled population and two-stage analysis. RESULTS: There was no significant difference in any measure of alfentanil clearance. Noncompartmental clearances (mean +/- SD) were 3.62 +/- 0.76, 3.81 +/- 0.96, and 3.60 +/- 0.84 ml/kg/ min, respectively, on days 2, 13, and 21 of the menstrual cycle. CONCLUSIONS: Alfentanil clearances were not different on menstrual cycle days 2, 13, and 21, strongly suggesting no change in P450 3A4 activity. Menstrual cycle differences in alfentanil clearances do not contribute to interindividual variability in alfentanil disposition in women. If other P450 3A4 substrates are comparable, then menstrual cycle variability in their metabolism may not be a consideration in dosing or in the design of pharmacokinetic investigations.     

Plasma and urinary catecholamines during the human ovulatory cycle

We measured plasma catecholamine concentrations and urinary catecholamine excretion during the ovulatory cycle in six healthy women. Plasma norepinephrine was consistently at its lowest during the follicular phase of the cycle. Plasma norepinephrine began to increase about 2 days before ovulation and continued to increase after ovulation, so that the average luteal phase NE concentration was significantly higher than the average follicular phase concentration (217 versus 143 pg/ml, p less than 0.001). Urinary norepinephrine excretion showed a similar but attenuated pattern. The results suggest that sympathetic neural activity changes with the phase of the ovulatory cycle. Cyclic patterning of plasma norepinephrine is one of many factors which should be considered in the design and analysis of studies which use plasma norepinephrine as an indicator of sympathetic neural activity in human disease states.     

Human endometrial perfusion after tubal occlusion

We examined variations in human endometrial microvascular perfusion across one menstrual cycle in women who had undergone tubal ligation and did not report unusual menstruation. Endometrial red blood cell flux was monitored by laser Doppler fluxmetry via a fibreoptic probe atraumatically inserted transvaginally into the uterus of each of 13 conscious volunteers. The observations obtained have been compared with those previously reported from a matched control group of women [B.J. Gannon et al., Hum. Reprod., 12, 132-139 (1997)]. Women who had undergone tubal occlusion for sterilization exhibited greater endometrial perfusion during menstruation (cycle days 0-5), at the time of ovulation (cycle days 13-16) and in the late secretory phase (cycle days 23-28) than occurred in controls. In addition, vasomotion in the study group was lower than that in controls in the early and late secretory phase (cycle days 17-22 and 23-28). Tubal occlusion appeared to alter endometrial perfusion. It is possible that the reported menstrual changes in women following tubal ligation are a consequence of altered endometrial perfusion; a possible causative relationship is discussed.     

Recombinant human inhibin-A administered early in the menstrual cycle alters concurrent pituitary and follicular, plus subsequent luteal, function in rhesus monkeys

Inhibin, a suppressor of pituitary FSH secretion in nonprimate species, may also act in the ovary to regulate follicular development. To examine whether inhibin has similar actions in primates, female rhesus monkeys (n = 3/treatment), exhibiting regular menstrual cycles, received sc injections of either vehicle or 60 micrograms/kg recombinant human inhibin-A at 0800 and 1600 h for 5 days beginning at menses. The vehicle-treated monkeys displayed menstrual cycles of normal length, with the follicular (11.3 +/- 2.5 days, mean +/- SE) and luteal (16.3 +/- 2.5 days) phases demarcated by midcycle peaks in serum estradiol (E) and bioactive LH. After the first inhibin injection, levels of immunoreactive inhibin A peaked at 10 ng/mL within 1 h and returned to baseline (< 0.1 ng/mL) before the second injection 8 h later. Although serum E and LH did not change, bioactive FSH decreased (to 66% of pretreatment levels, P < 0.05) within 8 h. Within 1 day, circulating bioactive FSH was less (P < 0.05) in inhibin-treated monkeys, compared with controls. By 2-3 days, serum E levels were also markedly (P < 0.05) reduced in inhibin-treated animals, whereas bioactive LH rose 3-fold (P < 0.05). After inhibin treatment, the midcycle rises in serum E and LH were delayed; hence, the follicular phase was prolonged (15.0 +/- 2.6 days, P < 0.05), compared with controls. Although the patterns and levels of serum LH circulating during the subsequent luteal phase seemed comparable in both groups, mean progesterone levels were suppressed to 2-3 ng/mL (P < 0.05) during the midluteal phase in inhibin-treated monkeys. However, the length of the luteal phase in inhibin-treated cycles (13.0 +/- 2.6 days) was not significantly altered. We conclude that exogenous inhibin rapidly diminishes pituitary FSH secretion in female monkeys during the early follicular phase of the menstrual cycle. This action, and/or other actions directly on the ovary, leads to subsequent effects on follicular steroidogenesis and pituitary LH secretion that culminate in an aberrant ovarian cycle characterized by an insufficient luteal phase. The study identifies, for the first time, possible activities and roles of inhibin during the ovarian cycle in primates.     

alpha-Tocopherol concentrations in plasma but not in lipoproteins fluctuate during the menstrual cycle in healthy premenopausal women

Because premenopausal women experience cyclic fluctuations of plasma carotenoids and their lipoprotein carriers, it was hypothesized that plasma alpha-tocopherol (A-T) fluctuates by phase of the menstrual cycle. Twelve free-living women, with a confirmed ovulatory cycle, were given a controlled diet for two consecutive menstrual cycles. Blood was drawn during the menses, early follicular, late follicular and luteal phases to simultaneously measure serum hormones, plasma lipoproteins and A-T concentrations, and A-T distribution in the lipoprotein fractions. Plasma A-T concentrations were significantly lower during menses than during the luteal phase by approximately 12% in each controlled diet cycle (P < 0.001). Adjustment for serum cholesterol and triglyceride concentrations did not alter these findings. The distributions of A-T in lipoprotein cholesterol fractions were not significantly different by menstrual phase. From 61 to 62% of A-T was concentrated in the LDL fraction, with another 9-14% in HDL2, 17-22% in HDL3 and the remaining 6-8% in VLDL+ IDL. There were no significant differences in lipoprotein cholesterol fractions by menstrual phase, except for a significant increase (P = 0.03) in HDL2 cholesterol from the early follicular to the late follicular phase. Spearman rank correlations from data during the second controlled diet month showed A-T in HDL2 in the late follicular phase was positively correlated with HDL cholesterol in the early follicular (r = 0.88), late follicular (r = 0.86) and luteal phases (r = 0.86) and with luteal apolipoprotein (ApoA-1) level (r = 0.90), and luteal HDL2 cholesterol (r = 0.83). A-T in HDL3 in the early follicular phase was negatively correlated with HDL2 cholesterol (r = -0.96) and ApoA-1 (r = -0.85), whereas luteal A-T in HDL3 was correlated with luteal HDL3 cholesterol (r = -0.79). Late follicular A-T in VLDL was positively correlated with early follicular HDL3 cholesterol and late follicular HDL3 cholesterol (r = 0.83). Fluctuations of A-T concentrations by phase of the menstrual cycle should be taken into consideration in future research concerning premenopausal women and the risk of chronic disease.