Blood Concentrations Of Oestradiol Research Articles

Endocrine disruption and reproductive impairment of methylparaben in adult zebrafish.

Methylparaben (MeP) is one of the most frequently used preservatives in our daily products. However, it is becoming an aquatic pollutant of emerging concern. To reveal the endocrine disruption mechanism and reproductive impairment of MeP, the present study exposed adult zebrafish to 0, 1, 3, and 10μg/L (0, 6.6, 19.7, and 65.7nM) of MeP for 28 days. The results showed that subchronic exposure to 10μg/L of MeP significantly increased the gonadosomatic index in zebrafish. Spermatogenesis and oogenesis were blocked by MeP at concentrations as low as 1μg/L. Furthermore, parental exposure to MeP induced developmental deficits in offspring larvae, by increasing mortality, stimulating precocious hatching, and elevating heart rate. Blood concentrations of estradiol, testosterone, and 11-keto-testosterone were consistently lowered in MeP exposure groups. Transcriptional results evidenced that the disturbance in steroidogenesis and feedback regulation mechanisms along the hypothalamic-pituitary-gonadal axis underlay the imbalance of sex hormones. In line with the low estradiol level, hepatic production of vitellogenin (VTG) was significantly down-regulated, subsequently leading to a deficiency of VTG supply during oogenesis. To our knowledge, this is the first study to provide systemic insight about the antiestrogenic activity and reproductive toxicity of MeP.

Effect of acupuncture at acupoint of Shenshu (BL 23) on the bones of ovariectomized rats

OBJECTIVETo investigate the effect of acupuncture at acupoint of Shenshu (BL 23) in ovariectomized rats and sham-operated rats. METHODSFemale Sprague-Dawley rats were divided into the following four groups (n = 12 each): sham operation only (Sham), sham operation with acupuncture (Sham + ACP), ovariectomy only (OVX), and ovariectomy with acupuncture (OVX + ACP). Operations were performed at the 9th week of age. Acupuncture of Shenshu (BL 23) was started at the 11th week of age and conducted 3 times per week until the 26th week of age. RESULTSAmong ovariectomized rats, the acupuncture-treated rats had significantly lower body weights and cross-linked N-telopeptide of type 1 collagen levels in the urine after 3 weeks of acupuncture treatment, higher bone mineral density of the lumbar vertebra after 7 weeks, and smaller trabecular separation of the sixth lumbar vertebra, measured by micro-computed tomography, after 17 weeks than control rats. These effects were not observed in sham-operated rats. Blood concentrations of estradiol were significantly higher in the OVX + ACP group than in the untreated group. Acupuncture treatment increased plasma testosterone levels in sham-operated rats, while this increase was not observed in OVX rats. CONCLUSIONAcupuncture of Shenshu (BL 23) prevents bone loss and structural changes by suppressing bone resorption.

Night shift work and other determinants of estradiol, testosterone, and dehydroepiandrosterone sulfate among middle-aged nurses and midwives.

The aims of our study were to (i) investigate the association between rotating night shift work and blood concentrations of estradiol, testosterone and dehydroepiandrosterone sulfate (DHEAS) and (2) evaluate the role of their non-occupational determinants. A cross-sectional study was conducted on 345 premenopausal and 187 postmenopausal nurses and midwives (263 women working rotating night shifts and 269 women working during days). Data from in-person interviews were used, anthropometric measurements were performed, and body mass index (BMI) and waist- to-hip ratio were calculated. Morning blood and spot urine samples were collected. Multiple linear regression models were fitted with hormone concentrations as dependent variables, and night shift work characteristics and demographic, reproductive, lifestyle and anthropometric determinants as independent variables. Modification of the effect by chronotype was examined. Among postmenopausal women, we observed a statistically significant positive association between the total duration of night shift work >15 years and estradiol level (P<0.05 when compared to night work duration <5 years). Night shift work characteristics were significantly associated with estradiol among morning-type postmenopausal women. The well-established associations between hormones and their major determinants, such as age and BMI, were confirmed. The findings of our study imply that prolonged night shift work may be associated with increased estradiol levels among postmenopausal women, especially among the morning-type postmenopausal women.

Central genomic regulation of the expression of oestrous behaviour in dairy cows: a review

The expression of oestrous behaviour in Holstein Friesian dairy cows has progressively decreased over the past 50 years. Reduced oestrus expression is one of the factors contributing to the current suboptimal reproductive efficiency in dairy farming. Variation between and within cows in the expression of oestrous behaviour is associated with variation in peripheral blood oestradiol concentrations during oestrus. In addition, there is evidence for a priming role of progesterone for the full display of oestrous behaviour. A higher rate of metabolic clearance of ovarian steroids could be one of the factors leading to lower peripheral blood concentrations of oestradiol and progesterone in high-producing dairy cows. Oestradiol acts on the brain by genomic, non-genomic and growth factor-dependent mechanisms. A firm base of understanding of the ovarian steroid-driven central genomic regulation of female sexual behaviour has been obtained from studies on rodents. These studies have resulted in the definition of five modules of oestradiol-activated genes in the brain, referred to as the GAPPS modules. In a recent series of studies, gene expression in the anterior pituitary and four brain areas (amygdala, hippocampus, dorsal hypothalamus and ventral hypothalamus) in oestrous and luteal phase cows, respectively, has been measured, and the relation with oestrous behaviour of these cows was analysed. These studies identified a number of genes of which the expression was associated with the intensity of oestrous behaviour. These genes could be grouped according to the GAPPS modules, suggesting close similarity of the regulation of oestrous behaviour in cows and female sexual behaviour in rodents. A better understanding of the central genomic regulation of the expression of oestrous behaviour in dairy cows may in due time contribute to improved (genomic) selection strategies for appropriate oestrus expression in high-producing dairy cows.

Plasma concentrations of PGFM and uterine and ovarian responses in early lactation dairy cows fed omega-3 and omega-6 fatty acids

A total of 120 dairy cows were assigned randomly to three diets to determine the effects of omega-6 or omega-3 fatty acid (FA) supplementation on uterine diseases, ovarian responses, and blood concentrations of estradiol, progesterone, and PGFM in lactating Holstein dairy cows. Diets contained either protected palm oil (C), extruded linseed (L), or roasted whole soybeans (S), and they were fed from calving to Day 70 postpartum. Estrous cycles were synchronized and ovarian follicular development was monitored daily for an entire cycle. There were no differences among diets in the incidence of lameness, mastitis, or metritis, but the incidence of clinical endometritis was lower (P < 0.05) in cows fed S (0%) compared with cows fed C (28.2%) and L (20.5%). Uterine involution in cows fed S occurred 3.77 and 2.78 days earlier, respectively, than in those fed C and L. The PGFM response 60 minutes after an oxytocin challenge was highest for cows fed S and lowest for cows fed L. Mean plasma progesterone concentration on Day 15 of the synchronized cycle was higher in cows fed S (14.5 ng/mL) and L (15.0 ng/mL) than in those fed C (12.0 ng/mL). The ovulatory follicle on Day 21 of the estrous cycle (estrous = Day 0) was larger in cows fed S (16.1 ± 0.9 mm) and L (15.7 ± 0.7 mm) compared with cows fed C (13.2 ± 0.87 mm; P = 0.02) but there were no significant differences between cows fed diets S and L. The mean number of small and medium follicles and diameter of subordinate follicle were similar among diets. In conclusion, feeding a source of omega-6 FA can be a strategy to improve uterine health after calving, although a source of omega-3 FA such as L should be fed after uterine involution to decrease PGF2α secretion.

Estradiol and Progesterone Strongly Inhibit the Innate Immune Response of Mononuclear Cells in Newborns

Newborns are particularly susceptible to bacterial infections due to qualitative and quantitative deficiencies of the neonatal innate immune system. However, the mechanisms underlying these deficiencies are poorly understood. Given that fetuses are exposed to high concentrations of estradiol and progesterone during gestation and at time of delivery, we analyzed the effects of these hormones on the response of neonatal innate immune cells to endotoxin, bacterial lipopeptide, and Escherichia coli and group B Streptococcus, the two most common causes of early-onset neonatal sepsis. Here we show that at concentrations present in umbilical cord blood, estradiol and progesterone are as powerful as hydrocortisone for inhibition of cytokine production by cord blood mononuclear cells (CBMCs) and newborn monocytes. Interestingly, CBMCs and newborn monocytes are more sensitive to the effects of estradiol and progesterone than adult peripheral blood mononuclear cells and monocytes. This increased sensitivity is associated with higher expression levels of estrogen and membrane progesterone receptors but is independent of a downregulation of Toll-like receptor 2 (TLR2), TLR4, and myeloid differentiation primary response gene 88 in newborn cells. Estradiol and progesterone mediate their anti-inflammatory activity through inhibition of the NF-κB pathway but not the mitogen-activated protein kinase pathway in CBMCs. Altogether, these results suggest that elevated umbilical cord blood concentrations of estradiol and progesterone acting on mononuclear cells expressing high levels of steroid receptors contribute to impair innate immune responses in newborns. Therefore, intrauterine exposure to estradiol and progesterone may participate in increasing susceptibility to infection during the neonatal period.

Effect of carazolol on the oestrous behaviour and concentrations of luteinising hormone and steroids in lactating cows during the periovulatory period

Twelve multiparous, cycling, lactating Holstein-Friesian cows were synchronised with prostaglandin F2α and treated with either 2·5 mg carazolol or saline. There were no differences between the peripheral blood concentrations of...

Circulating estradiol and hypothalamic corticotrophin releasing hormone enhances along with time after ovariectomy in rats: Effects of electroacupuncture

Repeated electroacupuncture (EA) stimulation is known to enhance the circulating level of estrogen in the ovariectomized rats by stimulating the activity of the hypothalamus-pituitary-adrenal axis. To explore the mechanism of EA in promoting the homeostasis in ovariectomized rats, the hypothalamic CRH content and its mRNA expression as well as the circulating estradiol in the rats along with time after ovariectomy were detected. Female rats were divided into fourteen groups: 1 month after ovariectomy (OVX1M), OVX2M, OVX3M, OVX4M, OVX5M, OVX6M; intact 1 month (INT1M), INT2M, INT3M, INT4M, INT5M, INT6M; OVX1M with EA (OVX1M+EA) and intact 1 month with EA (INT1M+EA). The blood concentrations of estradiol (E2) and total contents of hypothalamic CRH were measured by radioimmunoassay. The expressions of CRHmRNA were semiquantified by RT-PCR. The results showed that the blood E(2) concentrations increased gradually along with time after ovariectomy in the rats. The level was higher in OVX1M+EA than those in OVX1M, 2M, 3M (p < 0.05), which was near to the level in OVX6M. The total content (ng/g tissue) of hypothalamic CRH and the CRHmRNA expressions in the OVX6M rats were higher than other groups (p < 0.05). The CRH content or mRNA expression in the OVX1M+EA increased significantly compared with that in OVX1M (p < 0.05), and it was close to the level in the OVX4M and OVX5M. The results suggested that the circulating E2 and hypothalamic CRH enhances along with time after ovariectomy in rats, and the EA stimulation might speedup the process.

Hormonal Effects of Soy in Premenopausal Women and Men

Over the past few years, there has been increasing interest in the possible hormonal effects of soy and soy isoflavone consumption in both women and men. Soy consumption has been suggested to exert potentially cancer-preventive effects in premenopausal women, such as increased menstrual cycle length and sex hormone-binding globulin levels and decreased estrogen levels. There has been some concern that consumption of phytoestrogens might exert adverse effects on men's fertility, such as lowered testosterone levels and semen quality. The studies in women have provided modest support for beneficial effects. One cross-sectional study showed serum estrogens to be inversely associated with soy intake. Seven soy intervention studies controlled for phase of menstrual cycle. These studies provided 32-200 mg/d of isoflavones and generally showed decreased midcycle plasma gonadotropins and trends toward increased menstrual cycle length and decreased blood concentrations of estradiol, progesterone and sex hormone-binding globulin. A few studies also showed decreased urinary estrogens and increased ratios of urinary 2-(OH) to 16alpha-(OH) and 2-(OH) to 4-(OH) estrogens. Soy and isoflavone consumption does not seem to affect the endometrium in premenopausal women, although there have been weak estrogenic effects reported in the breast. Thus, studies in women have mostly been consistent with beneficial effects, although the magnitude of the effects is quite small and of uncertain significance. Only three intervention studies reported hormonal effects of soy isoflavones in men. These recent studies in men consuming soyfoods or supplements containing 40--70 mg/d of soy isoflavones showed few effects on plasma hormones or semen quality. These data do not support concerns about effects on reproductive hormones and semen quality.

Blood concentrations of estradiol and sex hormone-binding globulin in relation to age at menarche in premenopausal British and Japanese women

In a cross-sectional study, serum estradiol (E2) and sex hormone-binding globulin (SHBG) concentrations were not significantly related to age at menarche in premenopausal British women in the luteal or follicular phases of the cycle. In Japanese subjects in the luteal phase, a marginally higher concentration of E2 was observed in those who had undergone an early rather than a late menarche. In British women, previous oral contraceptive users had significantly lower luteal phase E2 concentrations than never users.

Effects of 4-hydroxyandrostenedione and exogenous testosterone on blood concentrations of oestradiol and oviducal embryo transport in the rat.

The effect of decreasing oestrogen secretion on the oviducal migration of embryos was investigated in pregnant rats. The reduction of oestradiol production was achieved by administration of the aromatase inhibitor 4-hydroxy-4-androstene-3,17-dione (4-OH-A) at various times after coitus. When 4-OH-A was administered from days 2 to 5, nearly half the embryos were retained in the oviducts at midday on day 5 of pregnancy, in contrast with control animals in which all embryos were transferred to the uterus. Shorter treatments were less effective. The rate of secretion of oestradiol from the ovary on days 2-5 of pregnancy in control rats was low in the morning and high in the afternoon. Treatment with 4-OH-A from days 2 to 5 reduced the secretory surges of oestradiol in the afternoon by 77% without significantly changing the progesterone output. Systemic testosterone levels were significantly increased by this treatment. To assess whether changes in the transport of ova were due to an increase in testosterone concentrations the influence of exogenous testosterone on embryo transport and oestradiol production was tested. Testosterone administered by subdermal implants from days 2 or 3 to day 5 disturbed embryo transport in a manner similar to that of 4-OH-A. The longest period of testosterone administration decreased ovarian oestradiol production by 82% without changing the secretion of progesterone.(ABSTRACT TRUNCATED AT 250 WORDS)

The dynamic interaction between steroids and gonadotropins in the mammalian ovulatory cycle

The interrelationship between steroid hormone secretion and gonadotropin secretion during the human menstrual cycle is a set of complex interactions. The temporal relationship between estradiol and progesterone secretion, the preovulatory surge of gonadotropins and the time of ovulation, has been studied extensively. The median time interval between the first rise of estradiol, progesterone, LH and FSH, and ovulation has been estimated to be 82.5 hr, 7.8 hr, 32 hr and 21.1 hr, respectively. The median time interval between peak blood concentrations of estradiol, LH and FSH, and the time of ovulation is estimated to be 24, 16.5 and 15.3 hr. There is considerable individual variation in the above mentioned estimates. The rising levels of blood estradiol that are secreted by the maturing ovarian follicles appear to be the primary trigger for the surge of gonadotropins leading to ovulation. In the experimental animal, the estrogen effect takes place at the level of the hypothalamus in the release of LHRH and at the level of the pituitary in increasing its sensitivity to LHRH. There appears to be a good correlation between the nuclear translocation of occupied estrogen receptors in the hypothalamus and the pituitary and the manifestation of estrogen effects. In the human, a rise in progesterone begins to take place after the first rise in LH has occurred. Progesterone appears to have both a stimulatory and inhibitory effect on gonadotropin secretion in the experimental animal and the human. Thus it exerts a fine-tune modulatory influence of estrogen effects which include enhancement of the estradiol induced gonadotropin surge, and perhaps the initiation of the midcycle FSH surge in the human. The abrupt termination of the preovulatory gonadotropin surge is difficult to explain because the pituitary gland is not depleted of its gonadotropin content or its capacity to secrete gonadotropins. Preliminary results suggests that progesterone by exerting its inhibitory influence may be responsible for the termination of the gonadotropin surge. This hypothesis, however, needs careful confirmation. The effects of progesterone may be manifested at higher brain centers, the hypothalamus and the pituitary, and may involve not only the release of LHRH but also an alteration of the pulsatile pattern of release of LHRH. The recognition of these components, along with the presence and control of LHRH degrading enzymes in the hypothalamus and the pituitary, emphasize the complexity of the system and the need for further work to gain a better understanding of the steroidal regulation of gonadotropin secretion.

Delay of ovulation in rats with sodium pentobarbitone: apparent differences between rats with 4- or 5-day reproductive cycles.

In rats with 4- or 5-day reproductive cycles various responses to the blockade of ovulation with sodium pentobarbitone at pro-oestrus (or at pro-oestrus and on the next day) were compared. The blood concentrations of oestradiol decreased rapidly during the 24 h period after injection of sodium pentobarbitone at pro-oestrus in rats with 5-day cycles. In those with 4-day cycles this response took almost a day to develop. Injection of sodium pentobarbitone at pro-oestrus and on the next day interfered with ovulation of the present crop of large follicles in rats with 5-day cycles. In 4-day cyclic rats this procedure delayed ovulation of these follicles by 48 h. Receptive behaviour was absent on the day after the second injection of sodium pentobarbitone in rats with 5-day cycles; some receptivity was, however, induced by the injection of gonadotrophin. The latter injection resulted in the release of a low number of eggs; fertilization of these eggs, however, did not occur. In 4-day cyclic rats receptive behaviour was recorded on the day after the second injection of sodium pentobarbitone: fertilization of delayed ovulated eggs took place normally but pregnancy was seen only rarely. The results indicated clear differences in responses to blockade of ovulation with sodium pentobarbitone between rats with 4- or 5-day cycles. The differences most probably result from a more advanced 'age' of preovulatory follicles at pro-oestrus of 5-day cycles compared with those of 4-day cycles. Experimental delay of ovulation reveals ageing changes and the probable onset of atresia at an earlier time after blockade in 5-day cyclic than in 4-day cyclic rats.

Effect of natural oestrogens on tryptophan metabolism: evidence for interference of oestrogens with kynureninase.

Urinary excretion of metabolites of the tryptophan-nicotinic acid ribonucleotide pathway, urinary excretion of 4-pyridoxic acid and blood concentrations of oestradiol and pyridoxal phosphate were studied in groups of post-menopausal women before or during treatment with natural oestrogens, i.e. oestradiol and oestriol, before and after loading doses of 9800 mumol L-tryptophan or 700 mumol L-kynurenine sulphate. Natural oestrogens induced abnormalities of tryptophan metabolism similar to those induced by synthetic oestrogens, and there was a dose related increase in urinary excretion of metabolites of the tryptophan-nicotinic acid ribonucleotide pathway before the kynureninase step. The increase in urinary excretion of these metabolites also after a loading dose of 700 mumol L-kynurenine indicates an inhibitory effect of oestrogens on kynureninase in vivo. Evidence is presented that this inhibition is an effect mediated through decreased availability of vitamin B6, the coenzyme of kynureninase, although the possibility of a direct effect of oestrogens on kynureninase can not be excluded.