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Results for “Ovulation”

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At least 19 recordsLinked to original sources

PubMed1979

[Mechanisms of ovulation in mammalian females].

The aim of this review was to briefly recapitulate the most important mechanisms involved in ovulation in the Mammals. The rabbit served as a model for the study of reflex ovulation. The triggering of ovulation by coitus was shown to be dependent on the activation of the hypothalamo-pituitary axis by sensory signals of multiple origin. The fundamental aspects of the hormonal and nervous machinery that governs spontaneous ovulation have been envisaged. The timing of LH ovulatory release and the mechanisms of action of this hormone at the ovarian level have been defined. Evidence was given that steroid hormones from ovarian and/or adrenal origin could evoke or modulate ovulatory processes. The structures responsible for both the tonic and clonic secretion of LH in subprimate and in primate mammals have been localized in the hypothalamus. The nervous endocrine mechanisms involving interactions between LHRH, neurotransmitters, prostaglandins and steroid hormones have been elucidated. Short loop feed back effects of pituitary hormones were shown to control LHRH secretion. Several examples were given attesting that the limbic system, the thalamus and the neocortex on one hand, and the environmental factors, on the other hand, were capable of modulating the activity of the hypothalamic structures implicated in the control of either ovulation or estrous rhythm regulation. An unitarian conception of the ovulatory mechanisms, based on the fact that coital-induced ovulation and estrogen-induced ovulation could occur in spontaneous and reflex ovulators respectively, has been proposed.

Adrenal Cortex↗

PubMed1979

Chemical inducers of ovulation: comparative results.

Chemical inducers of ovulation are frequently used to reestablish a normal hypothalamic-ovarian function in the sterile woman. At present, several types are available and it is useful to evaluate comparatively their efficacy. In this paper we present our results in 396 cases treated with some of these drugs. Clomiphene citrate was administered to 307 patient. Ovulation was obtained in 85.99% and pregnancy in 35.50%. There were 16 abortions (14.68%) among the 109 pregnancies obtained. Cisclomiphene was used in 11 cases. The ovulation rate was 81.81%, with 54.5% of pregnancies. Thirty-eight patients were treated with Cyclophenil. Ovulation was obtained in 71.05% of the cases and pregnancy in 23.68%. In forty cases Tamoxifen was administered: the ovulation rate was 95% and the pregnancy rate was 35%, but the abortion rate was 35%. Tolerance was good with all medications. They had similar adverse side effects (mild and rare). None produced overstimulation. With Cyclophenil and specially with Tamoxifen the cycles were longer. The incidence of abortion in the 131 pregnancies obtained was 14.68% with Clomiphene; none with Cisclomiphene; 11.11% with Cyclophenil, and 35.10% with Tamoxifen. We conclude that Clomiphene is the drug which gives the best results at present.

Anovulation↗

PubMed1979

The stimulatory effect of 5HT and the role of the paraventricular nucleus on PMS induced ovulation in the immature rat.

Immature rats can be induced to ovulate with pregnant mare serum (PMS) as long as they weigh over 60 g. In the rats weighing less than 60 g 5-hydroxytryptamine (5HT)-60 micrograms/rat intraventricularly or 2 micrograms/rat in the paraventricular nucleus (PVN)-stimulated ovulation. Injections into several other hypothalamic nuclei were ineffective. In rats weighing greater than 60 g, lesions of the PVN or injection of 10 micrograms/rat p-chlorophenylalanine into the PVN inhibited ovulation. The hypothalamic levels of 5HT and 5-hydroxy indole acetic acid (5HIAA) were generally lower in the afternoon and evening in the less than 60 g when compared with the greater than 60 g rats. It is possible that increased 5HT activity is required to stimulate ovulation and that its site of action is the PVN.

Animals↗

PubMedDate not supplied

The value of simple tests in the detection of human ovulation.

Cervical mucus viscosity (CMV) and fern test (FT), leukocyte alkaline phosphatase (LAP) activity, basal body temperature (BBT) and serum luteinizing hormone (LH) levels were determined during 31 normal menstrual cycles of 29 volunteers. The day of the serum LH surge was taken as a reference point in evaluating the reliability and sensitivity in predicting ovulation of the other tests studied. Serum LH surge was accompanied by a sudden decrease in CMV, an increase in LAP activity, a gradual increase in FT and biphasic changes of BBT. In about 95% of cycles studied, the lowest values of CMV and peak values of LAP activity appeared on the day of the serum LH surge or one day before or one day after. The lowest point of the BBT coincided with the LH surge in only 26% of cycles. In 53% of cycles, the span was greater than one day before or after the LH peak. The FT corresponded to the LH surge in only 33% of the cycles, while in an additional 33% the preovulatory FT response occurred more than one day before or after the LH surge. The results indicate that CMV and LAP tests are rapid, simple and reliable for monitoring follicular maturation and the timing of ovulation when carried out daily, and may be of value in monitoring treatment during the induction of ovulation.

Alkaline Phosphatase↗

PubMed1977

Augmentative effect of ascorbic acid upon induction of human ovulation in clomiphene-ineffective anovulatory women.

The effect of the administration of 1-ascorbic acid, either alone or combined with clomiphene, upon induction of human ovulation was investigated in clomiphene-inffective anovulatory women. Oral administration of daily 400 mg of ascorbic acid induced ovulation in two out of five habitually anovulatory cycles and in one out of eight first-grade amenorrhea cases, and was ineffective in all six second-grade hypothalamic amenorrhea cases. Combined administration of ascorbic acid with 5 days of clomiphene induced ovulation in five out of five habitually anovulatory cycles, in 10 out of 17 first-grade hypothalamic amenorrhea cases, and in two out of nine second-grade hypothalamic amenorrhea cases. Pregnancy was established in eight out of 18 sterile, habitually-anovulatory or first-grade amenorrheic women with the combined ascorbic acid-clomiphene therapy, and in one out of five sterile, habitually anovulatory women with ascorbic acid therapy alone. Since administration of ascorbic acid induced no changed in blood FSH, LH, and amount of cervical mucus, and it is well established that LH decreases dose-dependency of the ascorbic acid content in the rat ovaries, the possible site of action of ascorbic acid seems to be at the ovarian level.

Administration, Oral↗

PubMed1977

Ovulation timing by a radioreceptor assay for human luteinizing hormone.

Since predetermination of ovulation would be helpful in treatment of sterility, a quick, sensitive, and specific radioreceptor assay (RRA) for measurement of actual LH concentrations in human serum has been developed. Using partially purified membrane receptors from bovine testes, our assay system enabled precise measurement of LH within 4 hours. The detection limit of the present method is 0.78 ng LER 960/ml serum. The method was used to detect ovulation during four observation cycles each in eleven women who were undergoing treatment for infertility, such as recommended intercourse or artificial insemination because of reduced fertility of their husbands. In all women ovulations could be predicted by LH surge and were verified by laparoscopy within 36 hours. Insemination was carried out at the time of the characteristic increase of LH values around mid-cycle. Pregnancy occurred in three women during the observation period.

Adult↗

PubMed2026

A network of steroid receptor transcription factors regulates ovarian chromatin remodeling in the transition to ovulation.

Steroid receptors are transcription factors activated by progesterone, androgen, and glucocorticoid that bind the same canonical DNA sequence to modulate genome function in response to steroid hormones. However, the mechanisms defining unique physiological roles of these conserved receptors within the same tissue context, including the ovary, remain elusive. Here, we describe the dynamic association between each steroid receptor cistrome in the mouse ovary responding to the hormonal switch from follicle development to ovulation and generate chromatin conformation maps to define steroid receptor roles in promoter-enhancer interactions and gene transcription. Ovulatory hormones trigger progesterone receptor (PGR) and glucocorticoid receptor (NR3C1 [also known as GR]) binding to novel chromatin sites, promoting transcriptional activation of genes that are required for ovulation, whereas AR-chromatin interactions and androgen receptor (AR)-associated genes are repressed. Integration of genomic and transcriptomic data illustrates two parallel modes of PGR-mediated gene activation. Unique cooperation between PGR and GR enables their recruitment to previously inaccessible promoters, increasing histone acetylation, chromatin accessibility, and transcription activation, with PGR being the indispensable component of this transcriptional complex. Alternatively, PGR tethered to enhancers interacting with preaccessible, AR/GR-bound promoters induces gene activation. Our findings illustrate the multifaceted steroid receptor interactions that translate progressive change in steroid environments to collectively reprogram granulosa cell genome function to switch from follicle development to ovulation.

Journal Article↗

PubMed1977

Ovulation induction with human menopausal gonadotrophins: an evaluation of a variable daily dosage regimen.

Human menopausal gonadotrophins (HMG) were used together with human chorionic gonadotrophin (HCG) in 19 women and 39 treatment cycles in an attempt to induce ovulation. Daily 24 hours urinary total estrogen excretion rates were measured and HMG daily dosage was varied according to levels obtained. HCG injections were timed to coincide with an estimated urinary total estrogen excretion rate of 100-150 g per 24 hours. Thirty-one ovulatory cycles occurred (79%) and there were nine pregnancies (23%) of which five were multiple. Eleven cycles were complicated by hyperstimulation (25.6%) of which six were severe. The variable HMG dosage regimen was found to offer no advantages when compared with our standard daily dosage regimen. A rapid rise of estrogen excretion occurred in over 80% of hyperstimulation cycles, including all severe ones, and it was found that this rise could occur after the last dosage of HMG had been given. Because of this, it is proposed that HCG injections be delayed until 48 hours after the last injection of HMG. The finding of a value for the last available 24 hour urinary total estrogen excretion of less than 150 microgram can be taken as an indicator that hyperstimulation is unlikely to occur, and that HCG can safely be given. No indication was found that such a procedure would diminish ovulation or pregnancy rates.

Chorionic Gonadotropin↗

PubMed1978

Correlation between in vivo inhibition of gonadotropin release induced by LH-RH and the blockade of ovulation by synthetic analogues of LH-RH.

Several antagonists of LH-RH were examined for their anti-LH/FSH releasing activities in an immature male rat assay and for their ability to block ovulation. The in vivo inhibition of the release of LH and FSH induced by LH-RH over a 4-h period of time and the antiovulatory activity of these analogues were parallel to each other. The analogues that exhibited at least a 95% inhibition of LH and 77% of FSH release at 1 h and 75% and 40% of FSH release at 4 h in immature male rats, gave high blockade of ovulation. [D-Phe2, D-Trp3, D-Phe6]-LH-RH was the most potent analogue of the series and it seems to be active in men.

Amino Acid Sequence↗

PubMed1977