Plasma Estradiol Research Articles

Administration of aromatase inhibitor MPV-2213ad to blue fox vixens (Vulpes lagopus) as a model for contraception in female dogs

The interest in non-surgical approaches to contraception and fertility control in female dogs has increased in recent years. In this study the effect of an aromatase inhibitor (finrozole) was evaluated in fur production animals, farmed blue fox vixens, as a model for contraception in bitches. A total of 80 vixens were divided into 4 groups, receiving orally placebo (A) or finrozole 0.5 mg/kg (B), 3.5 mg/kg (C) or 24.5 mg/kg (D) for 21 consecutive days beginning in the pre-ovulatory period of heat. Monitoring of the vixens included clinical signs of heat, measurement of vaginal electrical resistance (VER) as well as oestradiol and progesterone concentrations in plasma. The approximate relation of the start of treatment to ovulation varied from 11 days before to one day after ovulation provided that the LH peak occurred 0.5–2 days before the VER peak and ovulation was then estimated to occur 2 days after the LH peak. Seventy vixens were artificially inseminated within 8 h after a 50 Ω decline in vaginal electrical resistance was detected. Ten vixens were not inseminated. Pregnancy was confirmed by transabdominal ultrasound examination and birth of cubs was recorded. The pregnancy rates in the groups were 89.5% (A), 81.3% (B), 55.6% (C) and 52.9% (D). The average number of live born pups in the four groups was 9.4 (A), 7.0 (B), 5.8 (C), and 3.8 (D), respectively. No deleterious effects (for instance malformations) of finrozole on pups could be verified. The administration of finrozole did not have a significant effect on oestradiol parameters and VER values in vixens. Progesterone values were significantly higher in treatment groups compared with the placebo group. The results indicate that pregnancy could be avoided by finrozole provided that doses of ≥3.5 mg/kg were used and the treatment was initiated at least four days before the day of artificial insemination. This corresponds with two to six days before ovulation provided that the LH peak occurred 0.5–2 days before the VER peak and that ovulation then occurred in average 2 days after the LH peak.

The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness

Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin (PRL) levels, which is necessary for incubation and connected with changes in hypothalamic–pituitary–gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine (PCPA) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone (P4), testosterone (T), estradiol (E2), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [GnRH] I, luteinizing hormone [LH] ß, follicle-stimulating hormone [FSH] ß) and lactotrophic (vasoactive intestinal peptide [VIP], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LHß, and FSHß and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.

Estrogen Replacement Improves Mesenteric Arterial Relaxation in UC Davis Pre‐diabetic Rats: Possible Involvement of Estrogen Receptor Beta

The risk of cardiovascular diseases (CVD) is lower in premenopausal women compared to men, and this lower risk is related to the presumptive cardioprotective effects of female sex hormones, estrogen in particular. However, premenopausal women may lose this protection with the onset of menopause and/or when they become diabetic. Little is known about the vascular function in presence or absence of estrogen at the early stage of diabetes.The objective of this study was to investigate the effects of 17β‐estradiol (E2) replacement on mesenteric arterial (MA) function in ovariectomized (ovex) UC Davis type 2 diabetes mellitus (UCD‐T2DM) rats at the pre‐diabetic stage. MA were obtained from four groups of ovex rats implanted with a subcutaneous pellet for 45 days: (1) Control (Ctrl), ovex + placebo, (2) Ctrl, ovex + E2 (1.5mg/pellet), (3) pre‐diabetic, ovex + placebo, (4) pre‐diabetic, ovex + E2. Endothelium‐dependent vasodilation (EDV) to acetylcholine (ACh, 10−8 to 10−5 M) in MA were measured before and after indomethacin (Indo, 10μM), a cyclooxygenase (COX) inhibitor; followed by addition of L‐NAME (200μM), a nitric oxide synthase (NOS) inhibitor. The MA expression of estrogen receptors (ERs) and plasma E2 concentration were determined by Western blotting and ELISA assay, respectively.E2 treatment significantly increased plasma estradiol concentration in both Ctrl and Prediabetic groups. Analysis of ERs showed a higher expression of ER‐beta only in E2‐treated prediabetic group. ACh responses were similar in Ctrl groups, regardless of E2 replacement. ACh induced relaxation was, however, markedly reduced in MA of placebo treated pre‐diabetic group compared with other groups. Treatment of pre‐diabetic with E2 enhanced relaxation to the same level as those from Ctrl rats. Blocking of both COX and NOS completely abolished the relaxation responses to ACh in pre‐diabetic groups, regardless of E2 replacement, indicating no contribution of EDHF‐type relaxation in these groups. However, the added effect of L‐NAME, in presence of Indo, in blocking ACh‐mediated vasodilation was much more prominent in E2‐treated prediabetic group when compared with placebo treated group, indicating an enhanced role of NO. On the other hand, both NO and EDHF remained important for EDV in Ctrl groups. Addition of L‐NAME, however, caused a much smaller reduction of EDV in E2 treated than in placebo treated arteries, suggesting EDHF is the predominant mediator of mesenteric vasorelaxation in this groups.Here, we show that EDV is impaired at pre‐diabetic stage, may be due to loss of EDHF. E2 treatment restores EDV in MA of pre‐diabetic group, possibly via elevated contribution of NO‐mediated relaxation by increased E2 signaling (via ER beta) in this group. The role of ER alpha remains to be investigated.Support or Funding InformationSupported by NHLBI.

Disruptive effects of nonylphenol on reproductive hormones, antioxidant enzymes, and histology of liver, kidney and gonads in Caspian trout smolts

The endocrine-disrupting effect of pollutants such as alkylphenols has been considered a major concern during recent years. Although the effects of nonylphenol on the reproductive hormones of fish have been investigated in several studies, the effect of this endocrine disruptor on reproductive hormones of immature fish and salmonid smolts has been less addressed. The present work studied the effects of 1, 10 and 100 μg/l concentrations of nonylphenol on the levels of plasma reproductive hormones and liver antioxidant enzymes as well as on histopathology of reproductive and non-reproductive organs of male and female Caspian brown trout (Salmo trutta caspius) smolts after 21 days of exposure. The results of the present study showed that environmentally relevant concentrations of nonylphenol affected plasma levels of sex steroids; gonadotropins, phosphorus, estradiol to testosterone ratio, and also caused histopathological lesions in liver, kidney and testis tissues of immature Caspian brown trout during smolting. Nonylphenol significantly increased the levels of estradiol in plasma of both male and female smolts exposed to nonylphenol compared with the control groups. Exposure to nonylphenol decreased testosterone and FSH levels in both genders. It has also increased plasma levels of LH in females but did not affect LH levels in male fish. Liver SOD and CAT content was decreased in nonylphenol-exposed smolts. Therefore, the release of this economically valuable and endangered species into the rivers contaminated with nonylphenol should be avoided as it can have significant effects on the development and reproductive function of smolts.

U-Shaped Association of Plasma Testosterone, and no Association of Plasma Estradiol, with Incidence of Fractures in Men.

Whether androgens, distinct from estrogen, maintain bone health during male aging has implications for understanding osteoporosis. We assessed associations of different sex hormones with incidence of any bone fracture or hip fracture in older men. Analysis of 3307 community-dwelling men aged 76.8 ± 3.5 years, median follow-up period of 10.6 years. Plasma testosterone (T), dihydrotestosterone (DHT), and estradiol (E2) assayed by mass spectrometry, sex hormone-binding globulin (SHBG), and luteinizing hormone (LH) using immunoassay. Incident fractures determined via data linkage. We analyzed probability of fracture and performed Cox regression adjusted for age, medical comorbidities, and frailty. Incident fractures occurred in 330 men, including 144 hip fractures. Probability plots suggested nonlinear relationships between hormones and risk of any fracture and hip fracture, with higher risk at lower and higher plasma T, lower E2, higher SHBG, and higher LH. In fully adjusted models, there was a U-shaped association of plasma T with incidence of any fracture (Quartile 2 [Q2] versus Q1: fully adjusted hazard ratio [HR] = 0.69, 95% confidence interval [CI] 0.51-0.94, P = .020; Q3: HR 0.59, 95% CI 0.42-0.83, P = .002) and hip fracture (Q2 versus Q1: HR 0.60, 95% CI 0.37-0.93, P = .043; Q3: HR 0.52, 95% CI 0.31-0.88, P = .015). DHT, E2, and LH were not associated with fracture. Higher SHBG was associated with hip fracture (Q4 versus Q1: HR 1.76, 95% CI 1.05-2.96, P = .033). Midrange plasma T was associated with lower incidence of any fracture and hip fracture, and higher SHBG with increased risk of hip fracture. Circulating androgen rather than estrogen represents a biomarker for hormone effects on bone driving fracture risk.

LC-APCI+-MS/MS method for the analysis of ten hormones and two endocannabinoids in plasma and hair from the mice with different gut microbiota

The effect of gut microbiota on the activity of the HPA and HPG axes and ECS is a short-term or long-lasting process remains unclear in rodents. However, the extant studies focused only on its short-term effect on the HPA activity because there is lack of reliable biomarkers characterizing short-term activity of the HPG axis and ECS and long-term activities of the three endocrine systems. The endogenous levels of aldosterone (ALD), 11-dehydrocorticosterone (11-DHC), estradiol (E2), estrone (E1), androstenedione (A4), dihydrotestosterone (DHT), corticosterone (CORT), dehydroepiandrosterone (DHEA), testosterone (T), progesterone (P), N-arachidonoyl ethanoamide (AEA) and 1-arachydonoyl glycerol (1-AG) in hair and plasma are the potential long-term and short-term biomarkers of the three systems. This study aimed to develop the sensitive and selective methods for simultaneous quantitation of the twelve compounds in rodent’s hair and plasma. Then the methods were used to explore the differences in the hair levels of the twelve compounds between the mice in XZ group possibly having gut microbiota with more diversity and SPF group possibly having gut microbiota with less diversity and the inter-group differences in the plasma levels in the response to 1-h restraint stress. The methods were based on high performance liquid chromatography tandem mass spectrometry with atmospheric pressure chemical ionization in positive mode. The methods were adopted for 20 mg hair and 100 μL plasma, respectively. Hair samples were incubated in methanol at 40 ℃ for 24 h, and were performed by solid phase extraction. Plasma samples were implemented by liquid-liquid extraction with ethyl acetate. The methods showed limit of quantification at 0.06–1.3 pg/mg and 0.03-0.6 ng/mL and recovery ranging between 87.7–115.1 % and 86.1–114.6 % for all compounds in rodent’s hair and plasma, and the intra-day and inter-day coefficients of variation less than 15 %, and good freeze/thaw and short-term stability. The present methods also had good reliability as demonstrated by the sex difference in the testosterone levels in hair and plasma. The inter-group comparison revealed that the mice in XZ group showed significantly higher hair levels than those in SPF group for 1-AG and most of hormones except for T and P. The non-stressed female mice in SPF showed significantly higher plasma levels than those in XZ for AEA and most of hormones except for E2, A4, DHT, T and 1-AG, but there were no inter-group differences for the stressed mice except for DHEA and 11-DHC and for the non-stressed male mice. Additionally, the stressed mice showed significantly higher corticosterone level in plasma than controls for male and female mice in XZ and male mice in SPF, but it was not true for female mice in SPF.

The Effect of Different Doses of Zearalenone in Feed on the Bioavailability of Zearalenone and Alpha-Zearalenol, and the Concentrations of Estradiol and Testosterone in the Peripheral Blood of Pre-Pubertal Gilts

The objective of this study was to determine the effect of long-term (48 days), per os administration of specific zearalenone (ZEN) doses (20 and 40 μg ZEN/kg BW in experimental groups EI and EII, which were equivalent to 200% and 400% of the upper range limit of the no-observed-adverse-effect-level (NOAEL), respectively) on the bioavailability of ZEN and the rate of changes in estradiol and testosterone concentrations in the peripheral blood of pre-pubertal gilts. ZEN and α-ZEL levels were similar until day 28. After day 28, α-ZEL concentrations increased significantly in group EI, whereas a significant rise in ZEN levels was noted in group EII. The presence of estradiol in peripheral blood plasma was not observed until day 20 of the experiment. Spontaneous secretion of estradiol was minimal, and it was determined at very low levels of up to 10 pg/mL in EI and EII groups. Testosterone concentrations ranged from 4 to 9 ng/mL in all groups. A decrease in the concentrations of both analyzed hormones was reported in the last stage of the experiment. The results of the experiment indicate that: (i) The bioavailability of ZEN in peripheral blood has low diagnostic value, (ii) exposure to low doses of ZEN induces minor changes in the concentrations of the analyzed hormones, which could lead to situational supraphysiological hormone levels and changes in endogenous hormonal balance.

Alterations of estrous cycle, 3\u03b2 hydroxysteroid dehydrogenase activity and progesterone synthesis in female rats after exposure to hypobaric hypoxia

The underlying mechanism regulating hypoxia induced alteration in female steroid hormones is first time explored in this study. To understand the mechanistic approach, female Sprague- Dawley rats were exposed to acute and chronic hypobaric hypoxia (282 mm-Hg, ~7620 m, 6 hours, 3 and 7 days). Estrous cycle, body weight, plasma progesterone and estradiol levels, morphology, histology and two key steroidogenic enzymes: 3ß hydroxysteroid dehydrogenase (HSD) and 17ß HSD activity of ovary and adrenal gland were studied. A persistent diestrous phase and a significant decrease in body weight were found in chronic hypoxia groups. Histological study suggested degenerative changes in ovarian corpus luteum of 7 days chronic hypobaric hypoxia (7CHH) group and a declined percentage of adrenocortical cells in 3 days chronic hypobaric hypoxia (3CHH) and 7CHH groups. Plasma estradiol level was unaltered, but progesterone level was decreased significantly in all hypoxic groups. Ovarian 3ß HSD activity was decreased significantly with increasing days of hypoxic treatment along with a significantly low adrenal 3ß HSD activity in 7CHH. In conclusion, hypobaric hypoxia causes a state of low circulatory progesterone level in females likely due to the degenerative changes in the female ovarian and adrenal tissues together with low steroidogenic 3ß HSD enzyme activity.

Plasma estradiol-17β, cortisol, and insulin concentrations and serum biochemical parameters surrounding puberty in Japanese Black beef bulls with normal and abnormal semen

The associations of semen abnormalities with circulating hormones (estrogens, glucocorticoid, insulin) and common biochemical parameters are unclear in beef bulls. We compared plasma concentrations of estradiol-17β, cortisol, and insulin and serum biochemical parameters surrounding puberty in Japanese Black beef bulls (n = 96) with normal post-thaw or abnormal semen (fresh and frozen). Blood samples were collected monthly from 4 to 24 months of age (n = 50) for the assays of plasma estradiol, cortisol, and insulin and every 3 months from 6 to 21 months of age (n = 92) for the serum biochemical analyses. Semen was collected weekly from 12 months until at least 18 months of age. Fresh semen was evaluated for semen volume, sperm progressive motility, concentrations, and morphological defects. The normal fresh semen was frozen by a standard method and examined for post-thaw sperm motility and fertility, which were evaluated for rates of transferable embryos. Bulls were classified as having either normal fresh semen or abnormal fresh semen (when at least one of the above test items was abnormal for 6 months). The normal fresh semen was categorized as having either normal post-thaw semen or low fertility post-thaw semen. The abnormal fresh semen was categorized as having sperm morphological defects, low motility, or morphological defects plus low motility. Plasma cortisol concentrations in the abnormal fresh semen group were higher than those of the normal fresh semen group (p < 0.0001). Plasma estradiol-17β and insulin concentrations in the low-fertility post-thaw semen group were lower than those of the normal post-thaw semen group (p < 0.0001). Serum aspartate aminotransferase and magnesium concentrations were greater for the abnormal fresh semen group vs. the normal fresh semen group (p < 0.005). These results suggest that fresh semen abnormality in pubertal beef bulls might be associated with increased circulating aspartate aminotransferase, magnesium and cortisol. Low-fertility post-thaw semen could have been involved with the lower peripheral estradiol and insulin levels in beef bulls.

Plasma Estradiol and Testosterone Levels and Ischemic Stroke in Postmenopausal Women.

Background and Purpose- Although exogenous hormone therapy (HT) use has been associated with increased risk of ischemic stroke in postmenopausal women, it remains unknown whether sex hormone levels contribute to ischemic stroke risk. We aimed to estimate associations between plasma sex hormone levels and ischemic stroke risk, by HT status, in a nested case-control study of postmenopausal women from the NHS (Nurses' Health Study). Methods- Women with confirmed incident ischemic stroke (n=419) were matched with controls (n=419) by age, HT use, and other factors. Plasma estradiol and testosterone levels were measured using liquid chromatography tandem mass spectrometry; SHBG (sex hormone-binding globulin) was assayed by electrochemiluminescence immunoassay. Associations of total and free estradiol and testosterone, the estradiol/testosterone ratio, and SHBG with ischemic stroke were estimated using conditional logistic regressions stratified by HT status with adjustment for matching and cardiovascular risk factors. Results- Current HT users had different hormone profiles from never/past users. No clear linear trends were observed between estradiol (total or free) levels or the estradiol/testosterone ratio and ischemic stroke risk among either current users (Ptrend>0.1) or never/past users (Ptrend>0.6). For both current and never/past users, the associations between some of the sex hormones and ischemic stroke differed by body mass index categories (Pinteraction≤0.04). For women with a body mass index <25 kg/m2, a higher estradiol/testosterone ratio was associated with significantly elevated ischemic stroke risk among current users (Ptrend=0.01), and higher levels of total and free estradiol were significantly associated with higher ischemic stroke risk among never/past users (Ptrend≤0.04). Testosterone and SHBG were not associated with ischemic stroke in either current or never/past users. Conclusions- Our findings do not support a role of sex hormone levels in mediating ischemic stroke risk among postmenopausal women. Replications in additional larger studies are required.

3-(4-Methylbenzylidene) camphor induced reproduction toxicity and antiandrogenicity in Japanese medaka (Oryzias latipes)

To assess the toxic effects of 3-(4-Methylbenzylidene) camphor (4-MBC) at environmentally relevant concentrations on the reproduction and development of Japanese medaka (Oryzias latipes), adult paired medaka (F0) were exposed to 5, 50, and 500 μg/L 4-MBC for 28 d in the current study. The fecundity and fertility were significantly decreased at 500 μg/L 4-MBC (p < 0.05). Histological observations showed that spermatogenesis in F0 males was significantly inhibited at 50 and 500 μg/L 4-MBC, similar to the effects obtained with all treatments of plasma 11-ketotestosterone (p < 0.05). Moreover, the plasma vitellogenin and estradiol levels in F0 females were significantly increased at 5 μg/L 4-MBC (p < 0.05). All the transcripts of hypothalamic-pituitary-gonadal (HPG) axis-related genes tested in the brains and gonads of males were significantly increased at all treatments, similar to the effects obtained for erα, erβ and vtg in the livers and in contrast to those found for arα in the livers (p < 0.05). Equal numbers of embryos were exposed to tap water and 4-MBC solutions. Significantly increased times to hatching, decreased hatching rates and decreased body lengths at 14-day post-hatching (dph) were obtained at 500 μg/L 4-MBC treatment (p < 0.05). The cumulative death rates at 14 dph were significantly increased with all the treatments (p < 0.05). Therefore, our results showed that long-term exposure to 50 and 500 μg/L 4-MBC causes reproductive and developmental toxicity and thus provide new insight into antiandrogenicity and the mechanism of 4-MBC in Japanese medaka.

The relationship between steroid hormones and seasonal reproductive events in free-living female Pygmy Rattlesnakes, Sistrurus miliarius

Steroid hormones regulate reproductive investment and play a critical role in coordinating reproductive responses to both short and long-term environmental change. Laboratory studies typically examine the mechanistic relationships among steroids and reproductive processes under controlled conditions and may fail to identify any seasonal patterns in regulatory mechanisms exhibited by free-living organisms. In snakes, field studies describing the seasonal relationships among steroids and male reproduction are prevalent. However, comparatively less work has been conducted on free-living female snakes. To bridge this gap in knowledge, we described the seasonal patterns of estradiol (E2), corticosterone (cort), and plasma constituents (total protein, albumin, phosphorus, and glucose) in relation to the seasonal events of the reproductive cycle in free-living female pygmy rattlesnakes (Sistrurus miliarius). We predicted to observe elevated E2 and plasma constituents during the spring vitellogenenic season, and that E2 would also be elevated during the fall mating season. Additionally, we hypothesized that cort acts to mobilize resources to meet the energetic challenges experienced during reproduction. We, therefore, predicted that elevated cort would be associated with the vitellogenic season and summer pregnancy, and that cort would be positively associated with elevated E2 and plasma constituents. In S. miliarius, plasma estradiol was significantly elevated during both the fall mating and spring vitellogenic seasons. Elevated E2 was associated with significantly higher plasma total protein, albumin, and phosphorous in both seasons, but unrelated to plasma glucose. Corticosterone was not elevated in individuals with elevated E2. Additionally, cort was not related to plasma total protein, albumin, or phosphorus, but was positively related to plasma glucose. Corticosterone was elevated during late pregnancy compared to early pregnancy and postpartum, and also elevated in pregnant compared to non-reproductive females sampled in the field. Our results indicate that the mechanistic links between steroids and reproductive processes may be seasonally uncoupled and highlight the need for the continued study of the hormonal coordination of reproduction in free-living vertebrates with diverse life histories.

Administration of melatonin improves testicular blood flow, circulating hormones, and semen quality in Shiba goats

Despite the role of melatonin in the regulation of the sleep-wake cycle and seasonal-reproduction, the present study investigated, for the first time, the potential role of melatonin on testicular blood flow (TBF) in goats. Twelve sexually mature male Shiba goats were exposed to a single s.c. injection of either melatonin suspended in one ml of corn oil (melatonin group; 36 mg/goat; n = 5) or one ml of corn oil (control group; n = 7). Monitoring the changes in TBF was done one week before (W-1), at the time of injection (W0), and once a week for 8 weeks after injection using color-pulsed Doppler ultrasonography. Concentrations of FSH, LH, inhibin, testosterone (T), estradiol (E2), and insulin-like growth factor-1 (IGF-1) in plasma were determined by radioimmunoassay. Melatonin and nitric oxide (NO) concentrations were measured using enzyme immunoassay kits. Moreover, semen collection and evaluation of some sperm parameters were performed once a week. Results revealed decreases (P < 0.05) in the Doppler indices (resistive index, pulsatility index) of the testicular arteries from W2 till W6 in the melatonin group. FSH, LH, and inhibin concentrations did not change between the two groups, while T, E2, IGF-1, NO, and melatonin concentrations increased (P < 0.05) in the melatonin group compared to the control. Estradiol and NO concentrations increased (P < 0.05), coinciding with decreases in the values of Doppler indices. Notable (P < 0.05) improvements in most parameters of semen quality were seen in the melatonin group. In conclusion, melatonin induced a stimulatory effect on TBF in Shiba goats and possibly, it could be a potential to improve male goats fertility.

Characterization of the hypothalamo–pituitary–gonadal axis in low and high egg producing turkey hens

Variation in egg production exists in commercial turkey hens, with low egg producing hens (LEPH) costing more per egg produced than high egg producing hens (HEPH). Egg production correlates with ovulation frequency, which is governed by the hypothalamic–pituitary–gonadal (HPG) axis. Ovulation is stimulated by a preovulatory surge (PS) of progesterone and luteinizing hormone, triggered by gonadotropin releasing hormone release and inhibited by gonadotropin inhibiting hormone. Differences between LEPH and HEPH were characterized by determining HPG axis plasma hormone profiles and mRNA levels for key genes, both outside and inside of the PS (n = 3 per group). Data were analyzed with a 2-way ANOVA using the mixed models procedure of SAS. In the HPG axis, plasma progesterone levels were not affected by egg production level but were elevated during the PS. In contrast, plasma estradiol levels were higher in HEPH than in LEPH but were not associated with the PS. LEPH exhibited decreased gene expression associated with ovulation stimulation and increased gene expression associated with ovulation inhibition in the hypothalamus and pituitary. In ovarian follicle cells, LEPH displayed decreased gene expression associated with progesterone, androgen, and estradiol production in the F1 follicle granulosa cells, F5 theca interna cells, and small white follicle cells, respectively. Different degrees of stimulation and inhibition within all tissues of the HPG axis were noted between LEPH and HEPH turkey hens, with HEPH showing higher expression of genes related to ovulation and steroidogenesis.

Reproductive phase-dependent variation, sexually dimorphic expression and sex steroids-mediated transcriptional regulation of lep and lepr in lymphoid organs of Channa punctata

The reproductive phase-dependent and sex-related differential expression of leptin (lep) and its receptor (lepr) in primary and secondary lymphoid organs of a highly nutritive economically important Channa punctata preempts the involvement of sex steroids in modulating intra-immuno-leptin system. This hypothesis was strengthened when plasma testosterone (T) and estradiol (E2) levels in male and female fish of reproductively active spawning and quiescent phases were correlated with lep and lepr expression in their immune organs. Splenic lep and lepr showed a negative correlation with T in both male and female, while with E2 there was a positive correlation in male and negative in female C. punctata. In head kidney, a contrasting correlation was observed as compared to spleen. To validate the implication of sex steroids in regulating leptin system in immune organs, in vivo and in vitro experiments were performed with DHT and E2. Upon administration, lep and lepr expression in tissues of either sex was downregulated. In addition, in vitro results with either of the sex steroids exemplified their direct involvement. Overall, this study, for the first time, reports correlation between sex steroids and transcript expression of leptin system in immune organs of a seasonally breeding vertebrate.

Associations of fluoride exposure with sex steroid hormones among U.S. children and adolescents, NHANES 2013–2016

Fluoride mediated disruption of sex steroid hormones has been demonstrated in animals. However, evidence from humans was limited and contradictory, especially for children and adolescents. Based on data of the National Health and Nutrition Survey (NHANES) 2013–2016, a total of 3392 subjects aged 6–19 years were analyzed in this cross-sectional study. Both plasma and water fluoride levels were quantified electrometrically using the ion-specific electrode. Sex steroid hormones of total testosterone, estradiol and sex hormone-binding globulin (SHBG) were tested in serum. Percent changes and 95% confidence intervals (CIs) in sex steroid hormones associated with tertiles of fluoride levels (setting the first as reference) were estimated using adjusted linear regression models by stratification of gender and age. Compared with subjects at the first tertile of plasma fluoride, percent changes (95% CIs) in testosterone were −8.08% (−17.36%, 2.25%) and −21.65% (−30.44%, −11.75%) for the second and third tertiles, respectively (P trend <0.001). Male adolescents at the third tertile of plasma fluoride had decreased levels of testosterone (percent change = −21.09%, 95% CIs = −36.61% to −1.77%). Similar inverse associations were also found when investigating the relationships between plasma fluoride and estradiol. Besides, the data indicated decreased levels of SHBG associated with water and plasma fluoride among the male adolescents (percent change of the third tertile = −9.39%, 95% CIs = −17.25% to −0.78%) and female children (percent change of the second tertile = −10.78%, 95% CIs = −17.55% to −3.45%), respectively. The data indicated gender- and age-specific inverse associations of fluoride in plasma and water with sex steroid hormones of total testosterone, estradiol and SHBG in U.S. children and adolescents. Prospective cohort studies are warranted to confirm the causality.

Associations of plasma IGF1, IGFBP3 and estradiol with leucocyte telomere length, a marker of biological age, in men.

Effects of insulin-like growth factor 1 (IGF1) and its binding proteins (IGFBPs) on ageing, and their interaction with sex hormones, remain uncertain. We examined associations of plasma IGF1, IGFBP1, IGFBP3, estradiol and testosterone, with leucocyte telomere length (LTL), a marker of biological age, in 2999 community-dwelling men aged 70-84 years. Plasma IGF1, IGFBP1 and IGFBP3 measured using immunoassay, sex hormones using mass spectrometry. LTL measured by PCR, expressed as ratio of telomeric to single-copy control gene DNA (T/S ratio). Linear regression models adjusted for age and cardio-metabolic risk factors, median splits defined low/high groups. Mean age was 76.7 ± 3.2 years. IGF1 and IGFBP3 showed age-adjusted correlations with LTL (coefficient 0.59, P = 0.001 and 0.45, P = 0.013 respectively), IGFBP1 did not. In multivariable-adjusted models IGF1 and IGFBP3 (but not IGFBP1) were associated with LTL (T/S ratio 0.015 higher per 1 s.d. increase in IGF1, P = 0.007, and 0.011 per 1 s.d. IGFBP3, P = 0.049). IGF1 and estradiol were independently associated with longer telomeres (T/S ratio 0.012 higher per 1 s.d. increase in estradiol, P = 0.027, when included in model with IGF1). Testosterone was not associated with LTL. Men with both high IGF1 (>133 µg/L) and high estradiol (>70 pmol/L) had longer LTL compared to men with lower values (multivariable-adjusted T/S ratio 1.20 vs 1.16, P = 0.018). Higher IGF1 and IGFBP3 are independently associated with longer telomeres in older men. Additive associations of higher IGF1 and higher estradiol with telomere length are present. Further studies are needed to determine whether these hormonal exposures cooperate to slow biological aging.

Influence of ipsilateral coexistence of the first wave dominant follicle and corpus luteum on ovarian dynamics and plasma sex steroid hormone concentrations in lactating dairy cows treated with human chorionic gonadotropin.

We examined the effect of human chorionic gonadotropin (hCG) treatment 5 days after estrus on ovarian dynamics and plasma progesterone (P4) and estradiol (E2) concentrations when the first-wave dominant follicle (DF) was ipsilateral or contralateral to the corpus luteum (CL) in lactating dairy cows. Seventy cows were divided into two groups: (1) ipsilateral group (IG; n = 37), in which the first-wave DF was ipsilateral to the CL, and (2) contralateral group (CG; n = 33), in which the first-wave DF was contralateral to the CL. IG and CG were further subdivided into two groups: non-treatment group (IG, n = 18; CG, n = 19), and hCG treatment group: administrated 1500 IU of hCG 5 days after estrus (IG, n = 19; CG, n = 14). Blood sampling and ovarian examination were performed at 3, 5, 7, 9, 11, and 13 days after estrus. Mean diameter of the first-wave DF on Day 9 tended (P = 0.067) to be larger in IG than in CG in the non-treatment group. Mean diameter of CL and plasma P4 and E2 concentrations did not differ between IG and CG in the non-treatment and hCG treatment groups. Accessory CL development did not differ between IG and CG in the hCG treatment group. Our findings indicate that CL development and plasma P4 and E2 concentrations were not affected by the existence of the first-wave DF; however, first-wave DF development was affected by the existence of a CL in the same ovary.

Genetic determinism of boar taint and relationship with growth traits, meat quality and lesions

Breeding entire males is an alternative to surgical castration to improve their welfare. However, entire males may have a major quality defect called boar taint. Boar taint is partly due to the presence of androstenone in fat. In this study, we estimated the genetic parameters between androstenone and production traits to evaluate the consequences of selection against boar taint for traits of interest. We focused on growth traits, meat quality, lesions, hormone levels and computerised tomography measurements in purebred Piétrain (P) or Piétrain cross Large White (X) entire males. The number of measured animals varied from 670 P and 734 X for hormones concentrations to 553 P and 645 X for computerised tomography measurements. Skin lesions were measured on live pigs shortly after mixing, at the end of the fattening period, and on carcasses. Heritabilities of traits measured by tomography ranged from low to high: femur density (P: 0.34, X: 0.69), loin eye area (P: 0.53, X: 0.88) and loin eye density (P: 0.12, X: 0.18). The mean number of lesions at each stage was lower in purebred pigs than in crossbreds (entering the fattening stage 4.01 in P and 4.68 in X; before slaughter 3.72 in P and 4.22 in X; on carcass 4.50 in P and 4.96 in X). We also observed a decrease in the average number of lesions between the two stages in live pigs. We found high genetic correlations between stages in purebred pigs (0.74 to 0.76) but low correlations (−0.30 to 0.29) in crossbred pigs. Selection aiming to decrease fat androstenone is feasible (h2 = 0.57 in P and h2 = 0.71 in X). It would have overall positive effects on meat production and quality traits. Selection aiming to reduce plasma oestradiol would strongly reduce the level of fat androstenone (rg = 0.89 in P and rg = 0.84 in X). Selection against oestradiol is easier and less invasive since it would only require a blood sample rather than a fat biopsy in live animals.

Effect of paracetamol treatment on maternal care and reproductive outcomes in female rat offspring.

Paracetamol (PAR) is one of the most commonly used drugs by pregnant women because it is considered safe for the mother and fetus. However, PAR is transferred into breast milk and crosses the blood-placental barrier, being present in the progeny during important stages of development. Intrauterine exposure to PAR may decrease the anogenital distance and follicle reserve in female rodent offspring. Therefore, the aim of the present study was to evaluate whether maternal PAR treatment altered the reproductive behaviour of dams and the sexual development of female rat offspring. Pregnant Wistar rats were gavaged daily with 350mg kg-1 day-1 PAR or water during gestation (from Gestation Day (GD) 6 until delivery) or during gestation and lactation (from GD6 until weaning). Maternal PAR treatment had maternal effects (increased grooming behaviour), and resulted in impaired sexual behaviour, decreased follicle reserve and increased plasma oestradiol concentrations in female offspring.