Ovine serum and pituitary isoforms of luteinising hormone during the luteal phase

The relative abundance of the different isoforms of pituitary and circulating luteinising hormone (LH) in ewes, at different times after the administration of gonadotrophin-releasing hormone (GnRH), during the luteal phase of the oestrous cycle was investigated. Sixteen ewes on Day 9 of their cycle were divided into four groups (n = 4). The control group (T0) received saline solution; the remaining animals received 100 microg GnRH (i.m.) 30, 90 or 180 min (T30, T90 and T180, respectively) before serum and pituitary gland collection. Luteinising hormone polymorphism was analysed by chromatofocusing (pH 10.5-3.5). The LH eluted from each chromatofocusing was grouped on the basis of the following three criteria: (1) according to the pH of elution (pH > or = 10-3.5); (2) as either a basic (pH > or = 7.5), neutral (pH 7.4-6.5) and acidic (pH < or = 6.4) elution of LH of serum and hypophyseal origin; and (3) on the basis of distinct isoforms, of which 10 (A-J) were identifiable in hypophyseal extracts and four (A-D) were found in the serum. In general, the most abundant forms of LH in both the pituitary and serum, at all times, were basic. However, that proportion was greater in hypophyseal extracts (84 +/- 3%, 81 +/- 4%, 82 +/- 3% and 83 +/- 2% at T0, T30, T90 and T180, respectively) than in serum (51 +/- 5%, 48 +/- 10% and 54 +/- 6% at T30, T90 and T180, respectively). Neutral and acidic LH made up a larger proportion of the total LH in sera (neutral: 17 +/- 4%, 20 +/- 6% and 23 +/- 3% at T30, T90 and T180, respectively; acidic: 32 +/- 8%, 32 +/- 11% and 23 +/- 6% at T30, T90 and T180, respectively) than in the pituitary extracts (neutral: 4.0 +/- 0.7%, 10 +/- 4%, 7 +/- 2% and 5.0 +/- 0.5% at T0, T30, T90 and T180, respectively; acidic: 12 +/- 3%, 11 +/- 2%, 12 +/- 2% and 12 +/- 2% at T0, T30, T90 and T180, respectively) at all times. These data reveal that the relative composition of the LH present in the pituitary gland and the LH secreted into the circulation is different, with more neutral and acidic isoforms being secreted. The pattern of circulating LH isoforms changes between 30 and 180 min after GnRH peak induction, with a greater proportion of isoform C (eluting between pH 7.0 and 6.5) at T180 compared with T30 and T90.     

Ontogeny of metabolic effects on embryonic development in lactating and weaned primiparous sows

Using an established experimental paradigm, feed restriction during the last week of lactation in primiparous sows reduces embryonic growth and development and produces female-specific embryonic mortality by Day 30 of gestation. Because this gender-specific loss of embryos at Day 30 was associated with changes in the variation of markers of epigenetic imprinting, the present study sought to establish the ontogeny of such epigenetic affects. Leucocyte DNA of restrict-fed sows exhibited decreased global methylation during the last week of lactation and during the return to oestrus (P < 0.05), but no associated changes in plasma folate and vitamin B(12). Furthermore, no changes in methylation of blastocyst DNA, embryonic sex ratios or development were evident at Day 6 of gestation that would characterise the underlying defects that reduced female embryo survival by Day 30. However, regardless of treatment, embryo recovery rates and synchrony in embryonic development were associated with the stage of development of the recovered embryos (r = 0.68; P < 0.001). The subset of sows classified as bearing litters with superior embryonic development had lower net energy balance over lactation (P < 0.01) and higher ovulation rates (P < 0.005) compared with sows classified as having poorer embryonic development. Collectively, these data suggest that a subset of litters within restrict-fed sows will be most sensitive to the latent epigenetic mechanisms that ultimately trigger gender-specific loss of embryos by Day 30 of gestation, but that these selective mechanisms are not evident by Day 6 of gestation.     

Secretion patterns of luteinising hormone, follicle-stimulating hormone and 17beta-oestradiol during oestrus and the mid-luteal phase of the oestrous cycle in mithun (Bos frontalis)

The present study reports the pulsatile secretion of gonadotrophins and 17beta-oestradiol (OE2) on the day of oestrus and at the mid-luteal phase of the oestrous cycle in mithun (Bos frontalis). The frequency of luteinising hormone (LH) and follicle-stimulating hormone (FSH) pulses was found to be greater (P < 0.05) on the day of oestrus than at the mid-luteal phase. In contrast, the amplitude of the LH and FSH pulses was greater (P < 0.01) at the mid-luteal phase than on the day of oestrus. A synchronised (P < 0.01) LH and FSH secretion pattern was found only at the mid-luteal phase. A pulsatile secretion pattern for OE2 in the peripheral circulation was evident for both phases of the oestrous cycle. The frequency of the OE2 pulses did not differ significantly in different phases of the oestrous cycle. In contrast, the amplitude of the OE2 pulses and the basal OE2 concentration were found to be greater (P < 0.01) at the mid-luteal phase than on the day of oestrus. A synchronised (P < 0.01) LH and OE2 secretion pattern was observed in both phases of the oestrous cycle. In contrast, a synchronised (P < 0.05) FSH and OE2 secretion pattern was found only on the day of oestrus. In conclusion, a different pattern of LH and FSH secretion was observed in both phases of the oestrous cycle, mainly on the day of oestrus, which indicates a differential regulatory mechanism of LH and FSH release. In addition, as in cattle, OE2 exerts a positive feedback on LH and FSH release on the day of oestrus and on LH release at the mid-luteal phase of the oestrous cycle in mithun. Also, as in cattle, the greater basal plasma OE2 concentration and increased amplitude of OE2 pulses exert a negative feedback on FSH release at the mid-luteal phase of the oestrous cycle.     

Efficacy of an inactivated Senecavirus A vaccine in weaned pigs and mature sows

Senecavirus A (SVA), commonly known as Seneca Valley virus (SVV) is a causative agent for vesicular disease in swine. It has been found across the globe including the United States, Brazil, and China. Clinical disease caused by this virus is identical to foot-and-mouth disease virus (FMDV). Since FMDV has the potential to cause severe economic consequences in FMDV-free countries, those countries are on high alert for signs of vesicles in swine and an investigation is performed to rule out the presence of FMDV if observed. In countries where SVA cases have continued to occur, investigations and testing can cause a burden on personnel and resources. The objectives of this study were to test the efficacy of a whole-virus inactivated SVA vaccine against challenge in nursery-aged pigs, mature sows, and to assess the protection of passive maternal immunity generated by immunized dams. Animals were given two doses of the vaccine intramuscularly three weeks apart and challenged intranasally two weeks after the second dose. Non-vaccinated animals challenged with SVA developed clinical signs of disease, replicated virus, and developed a neutralizing antibody response. Vaccinated animals had robust neutralizing titers after two doses; and after challenge, did not develop vesicular disease and had limited rectal shedding. Piglets suckling immunized dams and challenged with SVA at 3–6 days-of-age had neutralizing titers prior to challenge and did not replicate or shed virus. An efficacious vaccine could improve swine welfare and reduce the economic consequences of continued foreign animal disease investigations.     

Effect of a gonadotrophin-releasing hormone antagonist on luteinising hormone secretion and early pregnancy in gilts

The aims of the present study were: (1) to determine the duration of suppression of luteinising hormone (LH) following a single treatment with a gonadotrophin-releasing hormone (GnRH) antagonist (BIM-21009; Biomeasure) at a dose of 100 microg kg(-1); (2) to block LH pulses only for certain days of pregnancy; and (3) to determine the period of early pregnancy most susceptible to suppression of LH. Three groups of gilts were injected with 100 microg kg(-1) on Day 16 (n = 5), 14 (n = 6) or 19 (n = 4) of pregnancy. Blood for LH analysis was collected at 20-min intervals for 12 h on the day before treatment and during varying stages of early pregnancy. Blood for progesterone analysis was collected daily and development of pregnancy was followed using real-time ultrasound. Prior to treatment, gilts had 2.6 +/- 0.7 LH pulses per 12 h. The GnRH antagonist abolished LH pulses for a period of 2.7 +/- 1.8 days and, thereafter, suppressed the resumed LH pulses (P < 0.05). Pregnancy was disrupted in three pigs (20%) with a mean treatment-to-abortion period of 4.7 days concurrent with a mean treatment-to-progesterone decline interval of 4.3 days. In a proportion of pigs, short-term LH suppression may cause early disruption of pregnancy.     

Maternal malnutrition during lactation alters gonadotropin-releasing hormone expression in the hypothalamus of weaned male rat pups

Abstract

Gonadotropin-releasing hormone (GnRH) is the key hormone regulating reproduction. Its feedback regulation is exercised by estradiol. The early postnatal period is critical for sexual differentiation. Despite the fact that malnutrition-related reproductive suppression in rats is a well-documented phenomenon, we had no knowledge, until now, on how maternal malnutrition affects GnRH expression and estradiol serum concentrations of weaned pups. Six pregnant Wistar rats were separated into three groups at delivery with 6 pups each: control group (C) with free access to a standard diet containing 23% protein; protein energy restricted group (PER) with free access to an isoenergy and 8% protein diet; and an energy-restricted (ER) group receiving a standard diet in restricted quantities, which were calculated according to the mean ingestion of the PER group. At 21 days post partum, the animals were killed and the serum estradiol was evaluated by radioimmunoassay. Immunohistochemistry for GNRH was performed. The serum estradiol concentration was decreased in PER and ER groups compared with C (PER, 34%; ER, 19%;P < 0.01) and the staining of GNRH was restricted to arcuate nucleus and median eminence in the control group while in PER and ER stained processes aligned with the third ventricle wall (periventricular nucleus) were present. In conclusion, our data reinforce the concept that the maternal nutritional state during lactation is critical for sexual maturation since maternal malnutrition resulted in a neuron migration delay evidenced by an altered GnRH expression profile, probably a consequence of low estradiol serum levels.     

Dietary conjugated linoleic acid positively affects immunologic variables in lactating sows and piglets

We studied the effects of conjugated linoleic acid (CLA) on metabolic and immunologic variables in lactating sows and piglets. Gestating sows (n = 16) were assigned to 1 of 2 weight- and parity-matched groups supplemented with 0% (C) or 0.5% (T) of a CLA preparation containing 50% CLA isomers. Supplementation started in late pregnancy and continued throughout lactation. At weaning, 80 piglets, half from each group of sows, were assigned to 0% CLA (C) or 0.5% CLA (T). Thus, there were four groups of 20 piglets: C-C, C-T, T-T, and T-C. Body weight and the number of piglets per litter at birth and weaning, and the chemical composition of colostrum did not differ among the groups. CLA affected the fatty acid composition of colostrum fat; palmitoleic and gamma-linolenic acid were significantly lower compared with controls, whereas eicosenoic and eicosatrienoic acids were significantly higher. Feeding CLA increased (P < 0.05) colostrum IgG in sows. Sows fed CLA had higher (P < 0.05) serum leptin, IgG, and lysozyme. Nursing piglets from CLA-fed sows had significantly higher (P < 0.01) serum lysozyme and IgG. Consumption of CLA did not affect postweaning growth. Postweaning piglets fed CLA (T-T, C-T) had a higher IgG titer at 25 d (P < 0.05) and 35 d (P < 0.01) after weaning. Serum lysozyme was also higher at 25 d (P < 0.05) in CLA-fed piglets (T-T, C-T). At 35 d, serum alpha-1 acylglicoprotein was lower (P < 0.05) in piglets fed CLA. Dietary CLA had a positive effect on immunologic variables in lactating sows and piglets.     

Comparison of pregnancy outcomes of three luteal support protocols in frozen-thawed embryo transfer during the hormone replacement cycle

Objective To investigate the effects of three different luteal phase support protocols on pregnancy outcomes in hormone replacement therapy frozen-thawed embryo transfer (HRT-FET). Methods The clinical data of 3288 HRT-FET cycles in Reproductive Center of the Third Affiliated Hospital of Zhengzhou University from January 2016 to February 2019 were retrospective cohort study analyzed. The cycles were divided into three groups according to luteal phase support protocols. The patients received a combination of progesterone soft capsule and dydrogesterone in group A (478 cycles), the patients received a combination of progesterone vaginal sustained-release gel and dydrogesterone in group B (1293 cycles), the patients received a combination of progesterone injection and dydrogesterone in group C (887 cycles). Pregnancy outcomes and neonatal outcomes in group A, group B and group C were compared. Results The clinical pregnancy rate, the 12-week pregnancy rate and the live birth rate had no significant difference among the three groups (P>0.05). The rates of premature delivery and twin delivery [19.90% (78/ 392), 30.61% (120/392)] in group C were higher than those in group B [13.61% (109/801), P=0.011;20.47% (164/801), P<0.001]. The birth weight [(3 178.60±635.38) g] in group B was significantly higher than that in group C [(3 033.01±682.54) g, P<0.001] . There was no significant difference in the incidence of birth defects among the three groups (P>0.05). Logistic regression analysis showed that three different luteal phase support regimens were not associated with 12-week pregnancy rate. Conclusion In HRT-FET cycle, progesterone soft capsule or progesterone vaginal sustainedrelease gel combined with dydrogesterone can achieve the same pregnancy outcome as progesterone injection combined with dydrogesterone, but a large-scale prospective study is needed. © 2021 Chinese Medical Journals Publishing House Co.Ltdg. All rights reserved.     

来曲唑降低取卵后黄体期雌激素水平及OHSS的发生率

目的:研究卵巢过度刺激综合征(OHSS)高危患者取卵后使用来曲唑对黄体期性激素的影响及对OHSS的预防作用。方法:193例患者196个OHSS高危体外受精(IVF)/卵胞浆单精子注射(ICSl)周期取卵后行全部胚胎冷冻,并于取卵后根据是否添加来曲唑分为实验组和对照组,实验组取卵后口服来曲唑,对照组不予来曲唑。比较两组患者HCG日(d0)、d2、d4、d9的LH、E2、P水平及中、重度OHSS发生率。结果:实验组和对照组d0和d2的LH、E2、P以及d4LH和P、d9LH和P差异均无统计学意义(P>0.05),实验组d4 E2、d9E2和中、重度OHSS率低于对照组(P<0.01)。结论:OHSS高危患者取卵后添加来曲唑显著降低黄体期E2水平,有效降低中、重度OHSS发生率。     

Alterations in systemic concentrations of progesterone during the early luteal phase affect RBP4 expression in the bovine uterus

Systemic progesterone affects the timing and duration of uterine endometrial gene and protein expression and has significant effects on conceptus development. The objective of the present study was to examine how changes in progesterone concentrations during the early luteal phase affect retinol-binding protein (RBP4) mRNA and protein concentrations in the uterus. Endometrial tissue and uterine flushings were recovered on Days 7 and 13 of the oestrous cycle in heifers with high, normal and low progesterone concentrations. RBP4 mRNA and protein concentrations were higher (P<0.05) on Day 13 compared with Day 7 in heifers with high and control progesterone concentrations. However, there was no difference in RBP4 protein concentrations between Days 7 and 13 in heifers with low progesterone (P>0.05). On Day 7, although heifers with low progesterone had lower RBP4 mRNA expression compared with controls (P<0.05) there was no difference in protein concentrations between treatment groups. On Day 13, RBP4 mRNA was 2-fold higher (P<0.001) in heifers with high and control progesterone compared with their low-progesterone counterparts and RBP4 protein concentrations were over 2-fold higher (P<0.001) in heifers with high compared to low progesterone. In conclusion, progesterone modulates uterine RBP4 mRNA and protein abundance in a time- and concentration-dependent manner.     

Changes in the concentrations of testosterone, luteinising hormone and progesterone associated with administration of embelin.

The mode of action of embelin, a naturally occurring plant benzoquinone with male fertility regulating potential, was investigated. Sexually mature white New Zealand male rabbits were injected intra-muscularly with embelin (30 mg/kg body wt) on alternate days for 14 days (7 injections). Blood was collected on alternate days over 27-day period from the beginning of embelin administration. Testosterone and progesterone levels were measured by radioimmunoassay and luteinising hormone (LH) by mouse interstitial cell testosterone bioassay. There was a marked reduction of testosterone concentrations within two days of embelin administration and up to 90% reduction by the 6th day. LH showed a corresponding rise with the falling testosterone levels. Similarly, there was rapid increase in progesterone levels with the administration of embelin. Both the concentrations of progesterone and LH declined when embelin dosage was stopped. Evidence from the observed changes in the levels of the three hormones suggest that embelin disrupts production of testosterone at the testicular level.     

Progesterone levels in monkeys immunized with Pr-beta-hCG-TT after injection of hLH and hCG during luteal phase.

Rhesus monkeys immunized with the vaccine Pr-β-hCG-TT were injected with hCG/hLH in the luteal phase of the cycle in order to check whether the biological activity of these gonadotropins was neutralized by circulating antibodies. The immunized monkeys did not show a rise in plasma progesterone levels following one or more injections of hCG. The circulating antibodies did not, however, prevent an increase in plasma progesterone levels when hLH was administered.     

Nutritional restriction in lactating primiparous sows selectively affects female embryo survival and overall litter development

This study explored the possibility of sex-specific effects on embryonic survival in primiparous sows subjected to restricted feed intake during the last week of lactation and bred after weaning (Restrict; n = 16), compared with control sows fed close to ad libitum feed intakes (Control; n = 17). Restrict sows were in a substantial negative net energy balance at weaning, and lost 13% of estimated protein and 17% of fat mass during lactation, yet the weaning-to-oestrous interval and ovulation rate were not different between treatments. However, embryonic survival at Day 30 of gestation was lower (P < 0.05) in Restrict than Control sows, and selectively reduced the proportion of female embryos surviving (P < 0.01). A decrease in weight and crown-rump length of surviving female (P < 0.05) and male (P < 0.05) embryos was seen in Restrict litters. The mechanisms mediating this sex-specific effect on embryonic loss in feed-restricted sows are unclear. The data presented here indicate that feed-restriction during the last week of lactation in primiparous sows causes a selective decrease in survival of female embryos and limits the growth of all surviving embryos.     

Dietary conjugated linoleic acids alter adipose tissue and milk lipids of pregnant and lactating sows

Conjugated linoleic acids (CLA) have been shown to affect fatty acid synthesis in various tissues. The objective of the study was to compare the effect of a commercial source of CLA with a linoleic acid-enriched oil (LA), supplied to 12 multiparous sows during gestation and lactation, on adipose tissue and milk fatty acid composition. The CLA isomers detected in the CLA oil were (in order of magnitude) c9,t11; t10,c12; c9,c11; t9,t11/t10,t12 and c10,c12 and amounted to 58.9 g/100 g fat. Biopsies were taken from the backfat on d 7 and 97 of gestation and milk samples were collected on d 2, 9, 16 and 23 after farrowing. Collection of colostrum and mature milk samples took place at 1100 h for sows who farrowed in the morning or at 1500 h for those who farrowed in the afternoon. All major CLA isomers in the supplement were transferred to the tissue and milk fat and, compared with the LA group, significantly increased saturated fatty acid and decreased monounsaturated fatty acid levels in the tissue and milk. These findings suggest a distinct involvement of CLA in the de novo fatty acid synthesis and desaturation process in the adipose tissue and mammary gland. Estimated transfer efficiency of dietary CLA isomers was 41-52% for the backfat and 55-69% for the mature milk. The incorporation and uptake efficiency seemed to be selective with the highest values found for c9,t11-CLA. Overall, dietary CLA supplementation of sows during gestation and lactation markedly altered backfat and milk fatty acid composition.     

Alcohol inhibits suckling-induced oxytocin release in the lactating rat.

Oxytocin release in response to suckling was examined in primiparous lactating rats following alcohol administration. Lactating rats, with litters adjusted to eight pups on day 2, were implanted with an atrial catheter between days 6 to 8 of lactation. Four days later, alcohol in doses 0.0, 1.0, or 2.0 g/kg BW was infused, and blood alcohol levels achieved following infusion of initial doses were maintained for 4 h. On the day of alcohol infusion, pups were separated from the dams at 8:00 A.M. Following completion of alcohol infusion, a baseline blood sample was obtained, pups were returned to the dams, and additional samples were obtained 5, 10, 30, and 60 min after suckling started. Oxytocin levels in plasma were determined by radioimmunoassay. Suckling latencies and milk consumption during the 60 min of suckling were determined. Alcohol administration inhibited suckling-induced oxytocin release across all time points. Suckling latencies among groups were comparable. Milk consumption by pups during the 60 min of suckling was lower for the alcohol administered groups. The data from the present study demonstrate that acute alcohol administration to lactating rats inhibits suckling-induced oxytocin release resulting in reduction of milk secretion.     

Effect of systemic progesterone concentration on the expression of progesterone-responsive genes in the bovine endometrium during the early luteal phase

Increasing evidence indicates an association between the concentration of systemic progesterone during the early luteal phase of the oestrous cycle and embryo survival rate in cattle. We examined the relationship between the concentration of systemic progesterone on Days 4 to 8 post-ovulation and expression of progesterone receptor (PGR), oestrogen receptor +/- (ESR1) and retinol-binding protein (RBP) mRNA in the bovine endometrium. Heifers were blood sampled from the day of ovulation (Day 0) to Day 8 post-ovulation. On Day 4, animals were divided into low progesterone control (LC) and high progesterone control (HC) groups based on their plasma progesterone concentrations. Half of each group was supplemented with exogenous progesterone resulting in two further groups, low progesterone supplemented (LS) and high progesterone supplemented (HS). Endometrial tissues were recovered from all groups on Day 6 or Day 8 and gene expression was analysed following Northern blotting. Increasing progesterone concentrations were associated with decreased PGR and ESR1 expression. Duration-dependent effects of progesterone supplementation on ESR1 were evident and there was an effect of systemic progesterone concentrations between Day 0 and Day 4 on the expression of RBP at Days 6 and 8. Such progesterone-responsive changes in uterine gene expression are likely to affect embryo development.     

Anovulation, inadequate luteal phase and poor sperm penetration in cervical mucus during prolonged use of Norplant implants

Blood samples for progesterone assay were collected for a total of 49 cycles, from 27 volunteers using the NORPLANT system. Levonorgestrel determinations were carried out in the same samples. A group of 12 women with normal cycles were studied in the same manner to serve as controls. Of the 49 cycles studied, 20 (41%) were ovulatory. The mean levonorgestrel level in ovulatory patients was 0.34 +/- 0.11 ng/ml (S.D.) compared to 0.42 +/- 0.14 ng/ml (S.D.) in anovulatory cycles. Compared to the control group, progesterone levels were significantly lower for users of NORPLANT implants during days -12 to -10 (p less than 0.025), -9 to -7 (p less than 0.05), -6 to -4 (p less than 0.0005) and days -3 to -1 (p less than 0.01). Cervical mucus evaluations and post-coital tests were done around mid-cycle in 29 of the cycles studied. All samples of cervical mucus were of poor quality, viscous and scarce, with a mean SPK of 4.1 +/- 2.3 cm. Most had absent or atypical ferning. Twenty-one subjects (73%) had a post-coital score of 1, and 4 (14%) of zero. Thus, anovulation, inadequate luteal phase and the direct effect of the continuous administration of levonorgestrel over cervical function, all seem to contribute to the effectiveness of NORPLANT implants.     

Late follicular phase administration of levonorgestrel as an emergency contraceptive changes the secretory pattern of glycodelin in serum and endometrium during the luteal phase of the menstrual cycle

This study examined serum glycodelin concentrations and endometrial expression during the luteal phase following oral administration of levonorgestrel (LNG) at different stages of the ovarian cycle. Thirty women were recruited and allocated into three groups. All groups were studied during two consecutive cycles, a control cycle and the treatment cycle. In the treatment cycle, each woman received two doses of 0.75 mg LNG taken 12 h apart on days 3–4 before the luteinizing hormone (LH) surge (Group 1), at the time of LH rise (Group 2) and 48 h after the rise in LH was detected (Group 3). Serum progesterone (P) and glycodelin were measured daily during the luteal phase, and an endometrial biopsy was taken at day LH +9 for immunohistochemical glycodelin-A staining. In Group 1, serum P levels were significantly lower, serum glycodelin levels rose earlier and endometrial glycodelin-A expression was weaker than in Groups 2 and 3, in which no differences were found between control and treatment cycles. Levonorgestrel taken for emergency contraception (EC) prior to the LH surge alters the luteal phase secretory pattern of glycodelin in serum and endometrium. Based on the potent gamete adhesion inhibitory activity of glycodelin-A, the results may account for the action of LNG in EC in those women who take LNG before the LH surge.     

Inhibition of luteal phase progesterone levels in the rhesus monkey by epostane

This study examined the effect of epostane, a new antifertility drug, on normal and hCG-stimulated progesterone production during the luteal phase of the menstrual cycle in rhesus monkeys. When administered once each day for five days, epostane inhibited normal luteal phase progesterone levels in a dose-related fashion. Epostane also reduced the elevated luteal phase progesterone levels of animals treated with hCG indicating that the drug acts directly on the corpus luteum. These data suggest that epostane interferes with corpus luteum function in a primate and that the drug would be effective as an interceptive agent during early pregnancy.     

Assessment of human chorionic gonadotropin (hCG) levels during luteal phase in women using intrauterine contraception

103 Blood specimens, obtained during the luteal phase from women using various types of intrauterine contraceptive devices (IUD) were examined for the presence of hCG.

A sensitive radioreceptor assay for hCG was used. In contrast with recent reports, all specimens examined were negative for hCG. Hence, we question the validity of the hypothesis that the presence of an IUD may allow for fertilization, but cause degeneration of the blastocyst.