Comparison of the patterns of androstenedione, progesterone, and estradiol during the human menstrual cycle

Motivational Factors Affecting fluctuations of Female Sexual Activity at Menstruation

The hypothesis was tested that pre-menstrual and post-menstrual increases in sexual activity are due to anticipation of deprivation and rebound following deprivation (Ford & Beach, 1951). Thirty-five married women completed daily questionnaires about their sexual activity for at least two menstrual cycles. Evidence supported the hypothesis that the post-menstrual peak in intercourse is a rebound phenomenon. There was less evidence to support the hypothesis that a pre-menstrual rise represents anticipation of deprivation. In addition, there was a tendency to increase autosexual activity during periods of sexual abstention, which may represent a compensation phenomenon.

Analysis of testosterone pulsatility in women with ovulatory menstrual cycles

OBJECTIVE: To evaluate the pattern of the pulsatile secretion of testosterone in normal menstrual cycle. METHODS: Eight healthy women with ovulatory menstrual cycles were enrolled. Blood samples were collected at ten-minute intervals for six hours, starting between 7 and 8 am, after a ten-hour fasting, in three phases: mid-follicular (Day 7), late follicular (Day 12) and mid-luteal phase (Day 21). Samples were assayed for testosterone, LH and the baseline also for SHBG. RESULTS: Testosterone pulse frequency, mean amplitude pulse, percentage of increment in pulse amplitude, mean duration of pulses and pulse interval were similar in the three phases. LH pulsatility was statistically different among the three phases (p < 0.001) representing normal ovulatory cycles. CONCLUSIONS: These data increase the knowledge about the testosterone secretion profile in the human menstrual cycle and can be used as a contribution to clinical investigation in both hyperandrogenism and androgen insufficiency syndrome.

Endocrine regulation of menstruation

In women, endometrial morphology and function undergo characteristic changes every menstrual cycle. These changes are crucial for perpetuation of the species and are orchestrated to prepare the endometrium for implantation of a conceptus. In the absence of pregnancy, the human endometrium is sloughed off at menstruation over a period of a few days. Tissue repair, growth, angiogenesis, differentiation, and receptivity ensue to prepare the endometrium for implantation in the next cycle. Ovarian sex steroids through interaction with different cognate nuclear receptors regulate the expression of a cascade of local factors within the endometrium that act in an autocrine/paracrine and even intracrine manner. Such interactions initiate complex events within the endometrium that are crucial for implantation and, in the absence thereof, normal menstruation. A clearer understanding of regulation of normal endometrial function will provide an insight into causes of menstrual dysfunction such as menorrhagia (heavy menstrual bleeding) and dysmenorrhea (painful periods). The molecular pathways that precipitate these pathologies remain largely undefined. Future research efforts to provide greater insight into these pathways will lead to the development of novel drugs that would target identified aberrations in expression and/or of local uterine factors that are crucial for normal endometrial function.

Roles of androgens in the development, growth, and carcinogenesis of the mammary gland

Androgens influence the development and growth of the mammary gland in women. Treatment of animals and cultured cells with androgens has either inhibitory or stimulatory effects on the proliferation of mammary epithelia and cancer cells; the mechanisms for these dual functions are still not very clear and are discussed in this review. Epidemiological data suggest that, similar to increased estrogens, elevated androgens in serum may be associated with the development of breast cancer. Experiments in rodents have also shown that simultaneous treatment of androgen and estrogen synergizes for mammary gland carcinogenesis. Similar synergistic effects of both hormones have been observed for carcinogenesis of the uterine myometrium of female animals and for carcinogenesis of the prostate and deferens of males. There are also clinical and experimental indications for a possible association of elevated levels of both androgens and estrogens with the development of ovarian and endometrial cancers. A hypothesis is thus proposed that concomitant elevation in both androgens and estrogens may confer a greater risk for tumorigenesis of the mammary gland, and probably other female reproductive tissues than an elevation of each hormone alone.

The endocrinology of menstruation--a role for the immune system

The human endometrium displays characteristic features, both structural and functional, across the menstrual cycle. It is the sex steroid hormones, oestrogen and progesterone, that drive the endometrium through the different phases of the cycle. Oestrogen and progesterone act sequentially to regulate cellular concentrations of their respective receptors, this interaction initiates gene transcription. Thereafter a cascade of local events prepares the endometrium for implantation, but in the absence of pregnancy, progesterone withdrawal leads to menstruation and cyclic repair. Withdrawal of progesterone from an oestrogen-progesterone primed endometrium is the initiating event for the cascade of molecular and cellular interactions that result in menstruation. Progesterone withdrawal first affects cells with progesterone receptors. Early events in the menstrual process are vasoconstriction and cytokine up-regulation. The activation of lytic mechanisms is a later event and involves cells that may lack progesterone receptors, for example, uterine leucocytes and epithelial cells. Hence progesterone withdrawal results in a local increase of inflammatory mediators and the enzymes responsible for tissue breakdown. The total complex of local factors implicated in normal menstrual and aberrant menstrual bleeding are yet to be fully defined.

Expression of size-polymorphic androgen receptor (AR) gene in ovarian endometriosis according to the number of cytosine, adenine, and guanine (CAG) repeats in AR alleles

An increase in androgen receptor (AR) caused by estrogen is recognized as one of the biological phenomena related to estrogen-induced growth in uterine endometrium. The A/B region of AR gene in X chromosome involves the cytosine, adenine, and guanine (CAG) repeats. Random X chromosome inactivation with AR alleles in individual cells occurs in females. Therefore, approximately either paternal or maternal single dominant polymorphic AR mRNA must be expressed in neoplastic tissue originated from monoclone. This prompted us to determine deviated number of CAG repeats in AR mRNA to understand clonality in ovarian endometriosis. In all cases of heterozygous AR alleles, although paternal and maternal AR mRNAs from normal eutopic uterine endometrium were consistently expressed as AR alleles, either paternal or maternal single dominant AR mRNA expression was found in an individual ovarian endometrioma. Therefore, an individual ovarian endometrioma might be formed from an independent monoclonal ovarian endometriotic endometrial cell after inactivation of either AR allele in X chromosome.

Biological implications of estrogen and androgen effects on androgen receptor and its mRNA levels in human uterine endometrium

It has been shown that some effects of testosterone are different from those of its 5 alpha-reduced metabolite, dihydrotestosterone. Briefly, activities of testosterone might be related to cellular differentiation, whereas dihydrotestosterone acts on cellular proliferation. The number of testosterone binding sites in the uterine endometrium was increased by estradiol dipropionate, and this increase was down-regulated by testosterone cypionate. Dihydrotestosterone-specific binding sites in the endometrium were not modulated by estradiol dipropionate and testosterone cypionate. The dissociation constants of the binding sites for testosterone and dihydrotestosterone were not altered by these steroids. Estradiol dipropionate with or without testosterone cypionate induced androgen receptor mRNA expression in the endometrium. In conclusion, testosterone might predominantly affect cellular differentiation in the endometrium.

Effects of Estradiol and Testosterone on the Synthesis, Expression and Degradation of Androgen Receptor in Human Uterine Endometrial Fibroblasts

The mechanism of known receptor-mediated androgen effects on the endometrial stroma was studied in endometrial fibroblasts derived from human uterus. 17beta-Estradiol (E) induced the expressions of androgen receptor (AR) mRNA, and predominantly increased the level of testosterone-binding sites (TBS) in uterine endometrial fibroblasts. The effect on the level of dihydrotestosterone-binding sites (DHTBS) was similar but smaller. This result suggests that the AR mRNA expressed might encode TBS, but probably not DHTBS. The TBS level increased by estrogen was down-regulated by testosterone (T) + E, but the AR mRNA expression increased by E was not down-regulated by E + T in the fibroblasts. Although the synthesis rate of AR was slightly increased (p < 0.05) by E alone or E + T, the degradation rate of AR was significantly accelerated (p < 0.05) by E + T in the fibroblasts. This result suggests that T might stimulate the metabolic rate of TBS, but does not inhibit the synthesis rate of AR mRNA to TBS in endometrial fibroblasts. Copyright 1995 S. Karger AG, Basel

The effect of estrogen and androgen on androgen receptors and mRNA levels in uterine leiomyoma, myometrium and endometrium of human subjects

This study was designed to show the effect of estrogen and androgen on the level of testosterone and dihydrotestosterone specific binding sites (TBS and DHTBS, respectively) and to clarify the implication of androgen receptor mRNA expression to TBS and DHTBS in human uterine tissues. Estrogen mainly induces the increase of TBS and androgen receptor mRNA in uterine endometrium and leiomyoma. TBS increased by estrogen are downregulated when testosterone is given along with estrogen, while androgen receptor mRNA increased by estrogen was not significantly altered by testosterone with estrogen in endometrium and leiomyoma. These results suggest that the androgen receptor mRNA determined might encode TBS and that testosterone may stimulate the metabolic rate of TBS, or inhibit the translation rate of androgen receptor mRNA to TBS. Furthermore, the biological character of leiomyoma is considered to be an endometrial type.

Adrenal and gonadal androgen secretion in normal females

Both the adrenal and the ovary contain the biosynthetic pathways necessary for androgen synthesis and secretion. The fetal ovary is not very active but the fetal adrenal is an important source of DHAS. However the secretion of DHAS declines markedly after birth and until puberty there is little androgen secretion by either the adrenal or the ovary. Post-pubertally, the adrenal secretes DHAS, DHA, delta 4-A and T from the reticularis and probably the fasciculata. This secretion is under ACTH control, at least in part, but apparently also under control of another pituitary polypeptide tentatively called 'adrenal androgen secretory hormone'. THe adrenal secretion rates are in the range of 7-14 mg/day for DHAS, 3-4 mg/day for DHA, 1-1.5 mg/day for delta 4-A and 50 micrograms/day for T. Androgen secretion from the ovary arises in part from the theca cells of the follicle, the corpus luteum and the stromal cells, under LH control, and will vary somewhat during the normal menstrual cycle. The ovarian secretion rate in the follicular phase is 1-2 mg/day for DHA, 1-1.5 mg/day for delta 4-A and about 50 micrograms/day for T. In the peri-ovulatory period the secretion rate of delta 4-A can rise to 3-3.5 mg/day but there appears to be little change in the secretion of DHA and T. The normal ovary does not secrete significant amounts of DHAS. In about 50% of post-menopausal women the ovaries continue to secrete some T but little delta 4-A or DHA.

Androstenedione, 17 beta-estradiol and progesterone plasma levels in gonadotropins induction of ovulation

A comparison of peripheral patterns of androstenedione (A), 17 beta-estradiol (E2) and progesterone (P) is reported in ten infertile women during HMG-HCG induction of ovulation, in order to assess the site of ovarian secretion of plasma A and the possible influence on conception. Evidence for both the follicular and luteal secretion of plasma A is suggested, in addition to the stromal and adrenal contributions, since a highly significant (p less than 0.001) correlation between A and E2 plasma levels was shown during the treatment. In three cycles of conception, plasma A showed a periovulatory peak and drop, followed by a luteal increase, all of which are characteristic of E2.

Plasma androgen levels during the menstrual cycle

Utilizing RIA methods, T, DHT, delta 4, and DHEA levels were determined daily during a complete cycle in 15 normal young women with apparently normal ovulatory cycles. T, DHT, and delta 4 levels showed statistically significant cyclical variations, with highest values in the periovulatory period and lowest values in early follicular and late luteal phase. DHEA levels showed random variations during the cycle. The failure to detect these variations by some authors may be related to the relatively large interindividual variation in plasma levels.

Growth hormone excess and sexual precocity in polyostotic fibrous dysplasia (McCune-Albright syndrome): evidence for abnormal hypothalamic function

A 5-5/12-year-old boy with gigantism and precocious puberty associated with the McCune-Albright syndrome is presented. Serum concentrations of growth hormone were extremely elevated (128-163 ng/ml) and were not suppressed by hyperglycemia or chlorpromazine. Serum LH (7.4 +/- 1.0 SD mIU/ml) and FSH (5.3 +/- 0.3 SD mIU/ml) concentrations were in the range observed in midpuberty. The secretion pattern of LH was episodic. The administration of estradiol suppressed the secretion of FSH and had an apparent positive feedback effect on release of LH. These findings are compatible with abnormal hypothalamic function as the mechanism for the endocrinopathies associated with the McCune-Albright syndrome.

Serum androstenedione levels during normal and human menopausal gonadotropin-induced human pregnancies

17-Hydroxyprogesterone (17-OHP) and androstenedione (A) were measured frequently during the first trimester of five human pregnancies. Two were normally conceived and three were HMG induced. Of the HMG induced, two showed signs of hyperstimulation and one did not. 17-OHP and A patterns were very similar in the HMG-induced pregnancies from about days 25 to 60, after which the 17-OHP levels continued to drop. The A remained fairly constant after that time. In the normally conceived pregnancies the 17-OHP showed its characteristic rise and fall from about days 25 to 60, but A remained relatively constant throughout this period of time. The pattern of A in normal pregnancies is in marked contrast to that observed in HMG-induced pregnancies. Results from HMG-induced pregnancied may not, therefore, be always applicable to normal ones.