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Ovarian Response (ovarian + response)

Distribution by Scientific Domains

Medical Sciences	85%

Selected Abstracts

Endocrine and Ovarian Responses to Prolonged Adrenal Stimulation at the Time of Induced Corpus Luteum Regression

REPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2006
G Gabai
Contents The endocrine and ovarian responses to prolonged adrenal stimulation at the time of corpus luteum (CL) regression were studied in non-lactating non-pregnant Friesian cows. Cows were synchronized with two cloprostenol (PG) injections 11 days apart (second PG referred as time 0). Experiment 1 was carried out on five animals in two phases with a resting period in between. Between ,48 and 84 h, animals received 12 injections of either saline (CTR) or adrenocorticotrophic hormone (ACTH) agonist (Synacthen; SYN) every 12 h. Cortisol (C), progesterone (P4), oestradiol (E2) and LH were analysed in the blood samples collected every 8,12 h between days ,3 and 4. Pulsatile LH release was studied 4 h before and 4 h after naloxone administration beginning at 96 h. Experiment 2 was carried out on four cows in a cross-over experimental design (two phases, with a resting period in between). Treatments were performed by administering either saline (CTR) or Synacthen (SYN) every 12 h between ,36 and 24 h. The concentrations of C, P4 and E2 were measured in blood plasma every 4,12 h from days ,3 to 3, then every day from days 5 to 9. In both experiments, ovaries were examined by ultrasonography every 1,3 days. ACTH administration induced a significant increase (p < 0.001) of plasma C lasting for 7 days (experiment 1), and for 3,4 days (experiment 2). Plasma C returned to baseline levels within 6 days (expt 1) or 36 h (expt 2) after treatment interruption. During the SYN phase, LH pre-ovulatory surge was not detectable. During the CTR phase, naloxone administration induced a significant increase (p < 0.05) of average LH concentrations that was not evident during the SYN phase. The dominant follicle development was retarded and mean plasma E2 concentrations were significantly lower during the SYN phase (p < 0.01). Luteolysis was completed within 2 days. However, P4 decline between 0 and 4 h was slower (p < 0.01) during the SYN phase. Our results indicate that, under prolonged adrenal stimulation, follicular development is delayed and LH release is impaired, which are independent of CL function. [source]

Testosterone response to GnRH in a female songbird varies with stage of reproduction: implications for adult behaviour and maternal effects

FUNCTIONAL ECOLOGY, Issue 4 2007
JODIE M. JAWOR
Summary 1Despite considerable recent interest in plasma and yolk testosterone (T) in female birds, relatively little is known about environmental regulation of female T, individual variation in female T or the relationship between plasma and yolk T. 2In breeding females of a wild population of dark-eyed junco (Junco hyemalis), we assessed variation in the responsiveness of the hypothalamo-pituitary-gonadal (HPG) axis to a challenge with gonadotropin-releasing hormone (GnRH) by measuring circulating T before and 30 min after a standardized injection of GnRH. We asked whether response to challenge varied seasonally or with stage of reproduction and whether it was repeatable within individuals or related to T deposited in eggs. 3Initial and post-challenge levels of T were measured using enzyme immunoassay. In a subset of these females, luteinising hormone (LH) was measured using radioimmunoassay (RIA). In addition, eggs were collected from nests of 15 females that had received a GnRH challenge, and yolk T was measured using RIA. 4During most of the breeding season, plasma T did not increase in response to GnRH. GnRH consistently caused increases in plasma T only during the 7 days before oviposition, when females were rapidly depositing yolk in eggs but had not yet begun to lay them. Among a small subset of females we found a positive correlation between the magnitude of this increase in plasma T in response to GnRH during egg development and the amount of T deposited in the yolk of eggs collected at a later time. 5These results suggest that ovarian response to GnRH-induced increases in LH is greatest when females are actively depositing yolk into eggs. Factors that stimulate the release of GnRH during egg formation may result in higher levels of plasma T which could influence adult female behaviour. Further, because plasma T was correlated with later yolk T, factors that stimulate GnRH release may also lead to higher levels of yolk T potentially influencing offspring development or behaviour. [source]

Estrogen administration during superovulation increases oocyte quality and expressions of vascular endothelial growth factor and nitric oxide synthase in the ovary

JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 4 2010
Choong-Sik Ha
Abstract Aims:, This study investigated whether estrogen administration during superovulation enhances oocyte quality using a mice model. We also investigated whether this estrogen treatment regulates the expressions of angiogenic factors, such as vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS), in the ovary. Method:, Female mice were co-injected with various doses of estrogen (1 µM, 10 µM and 100 µM) and pregnant mare serum gonadotrophin during superovulation, followed by human chorionic gonadotrophin injection 48 hours later. Then they were mated with individual males. After 18 hours, zygotes were flushed and cultured to blastocyst. The expression of VEGF and eNOS in the ovary was examined using Western blot and immunohistochemistry. The control group was superovulated without estrogen. Results:, Both numbers of ovulated zygotes and the rate of embryo development to blastocyst were significantly increased in the 1-µM estrogen dose compared to the control group. VEGF and eNOS expressions were stimulated by estrogen treatment. In particular, VEGF expression was significantly increased at 1-µM estrogen concentration, whereas, eNOS expression was significantly increased in all estrogen concentrations compared to controls. Conclusions:, The study showed that estrogen co-injection during superovulation increased the ovarian response, embryo developmental competence and expressions of VEGF and eNOS in the ovary. [source]

The influence of body weight on response to ovulation induction with gonadotrophins in 335 women with World Health Organization group II anovulatory infertility

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 10 2006
AH Balen
Objective, To assess the influence of body weight on the outcome of ovulation induction in women with World Health Organization (WHO) group II anovulatory infertility. Design, The combined results of two studies in which either a highly purified urinary follicle-stimulating hormone or highly purified urinary menotrophin were compared with recombinant follicle-stimulating hormone. Setting, Thirty-six fertility clinics. Population, A total of 335 women with WHO group II anovulatory infertility failing to ovulate or conceive on clomifene citrate. Methods, Ovarian stimulation using a low-dose step-up protocol. Main outcome measures, The effects of body weight on ovarian response, ovulation rate and pregnancy rate after one treatment cycle. Results, With increasing body mass index (BMI), a higher threshold dose of gonadotrophins was required and there were more days of stimulation; yet, despite a greater concentration of antral follicles, there were fewer intermediate and large follicles. There was no difference in the rates of ovulation and clinical pregnancy in relation to body weight. Conclusions, Body weight affects gonadotrophin requirements but not overall outcome of ovulation induction in women with anovulatory polycystic ovary syndrome and a BMI of less than 35 kg/m2. [source]

Anti-Müllerian hormone (AMH) in female reproduction: is measurement of circulating AMH a useful tool?

CLINICAL ENDOCRINOLOGY, Issue 6 2006
A. La Marca
Summary Anti-Müllerian hormone (AMH) is a dimeric glycoprotein, a member of the transforming growth factor (TGF) superfamily. It is produced exclusively in the gonads and is involved in the regulation of follicular growth and development. In the ovary AMH is produced by the granulosa cells of early developing follicles and seems to be able to inhibit the initiation of primordial follicle growth and FSH-induced follicle growth. As AMH is largely expressed throughout folliculogenesis, from the primary follicular stage towards the antral stage, serum levels of AMH may represent both the quantity and quality of the ovarian follicle pool. Compared to other ovarian tests, AMH seems to be the best marker reflecting the decline of reproductive age. AMH measurement could be useful in the prediction of the menopausal transition. It could also be used to predict poor ovarian response and possibly the prognosis of in vitro fertilization (IVF) cycles. AMH has been shown to be a good surrogate marker for polycystic ovary syndrome (PCOS). Finally, its use as a marker for granulosa cell tumours has been proposed. A clearer understanding of its role in ovarian physiology may help clinicians to find a role for AMH measurement in the field of reproductive medicine. [source]

FSH and ovarian response: spontaneous recovery of pituitary,ovarian activity during the pill-free period vs. exogenous recombinant FSH during high-dose combined oral contraceptives

CLINICAL ENDOCRINOLOGY, Issue 4 2002
A. M. Van Heusden
Summary ojbective Compare spontaneous recovery of pituitary,ovarian activity during the pill-free period following the correct use of low-dose oral contraceptives and subsequent ovarian function during the administration of exogenous recombinant FSH (recFSH) after switching to continued Lyndiol® (2·5 mg lynestrenol + 0·05 mg ethinyl-oestradiol) medication. design Prospective, randomized, group-comparative, single-centre study. Following the monitoring of the pill-free period (week 1) and subsequent treatment with Lyndiol® (for a total of 5 weeks), all subjects were randomly allocated to one of four groups receiving daily FSH injections for 1 week [75, 150, 225 IU recFSH or 150 IU purified urinary FSH (uFSH)] during the fourth week of Lyndiol® use. patients Thirty-six healthy volunteers aged 18,39 years, prestudy oral contraceptive use for at least 3 months, cycle length between 24 and 35 days. measurements Serum FSH, LH and oestradiol (E2) concentrations as well as transvaginal ultrasound assessment of the number and diameter of follicles > 2 mm were used to monitor pituitary ovarian function. results At the start of the pill-free period following the prestudy contraceptive medication, 67% of the women presented with LH and FSH levels < 1 IU/l and only one follicle > 10 mm was observed. Initial levels of LH and FSH correlated (P < 0·05) with the extent of pituitary,ovarian activity during the pill-free period. At the end of the pill-free period a follicle > 10 mm had emerged in one subject only. During the first 3 days of Lyndiol® use, seven women (19%) eventually showed at least one follicle > 10 mm. During combined exogenous FSH and Lyndiol® administration, LH levels remained completely suppressed (, 0·5 IU/l) in all women studied. FSH levels and number and size of follicles increased with increasing doses of exogenous FSH in a dose-dependent manner. E2 levels remained low in all groups (< 150 pmol/l). During the week following FSH administration, FSH levels and E2 levels decreased gradually while the number of follicles > 10 mm still increased. conclusions We have confirmed that dominant follicles > 10 mm are present at the end of the pill-free period and during the first days after resumption of pill intake. Once follicles > 10 mm arose at the end of the pill-free period, continued use of Lyndiol® did not reduce follicle diameters. One week of Lyndiol® reduces pituitary,ovarian activity to levels observed after 3 weeks of low-dose pills. FSH administration during Lyndiol® resulted in dose-dependent follicle growth despite extremely low LH levels. E2 secretion (56 ± 51 pmol/l) occurred to a limited and variable extent along with extremely low serum LH concentrations. Recovery of pituitary,ovarian activity at the end of the pill-free period is comparable to FSH levels and follicle dynamics following 7 days of 75,150 IU/l recFSH. [source]