The effect of hCG treatment on Day 12 post-mating on ovarian function and reproductive performance of ewes and ewe lambs

The objectives of this study were to determine the effect of a single intramuscular injection of 200 IU hCG (Chorulon) on Day 12 post-mating on ovarian function and subsequent lambing performance in ewes and ewe lambs bred at synchronised oestrus during the breeding season and on the lambing performance of ewes induced to breed during late anoestrus. All animals were mated to rams at synchronised oestrus and on Day 12 post-mating given normal saline or 200 IU hCG.In Experiment 1, laparoscopic results showed that hCG treatment induced accessory corpora lutea in ewes (control = 0/7; hCG = 5/7) but not in ewe lambs (control = 0/7; hCG = 0/7).In Experiment 2, hCG treatment did not improve the lambing rate (control = 50; hCG = 57) or the litter size (control = 1.80; hCG = 1.96) in ewes (control = 100; hCG = 91). However, hCG treatment significantly (P > 0.05) improved the lambing rate (control = 29; hCG = 58; P < 0.05) in ewes conceiving at the first oestrus after treatment. hCG treatment (control = 42; hCG = 42) also failed to improve the lambing rate in ewe lambs (control = 48; hCG = 41).In Experiment 3, hCG treatment had no significant (P > 0.05) effect on the lambing rate (control = 72; hCG = 62) or the litter size (control = 1.59; hCG = 1.58) in ewes (control = 111; hCG = 115) induced to breed during anoestrus or on ewes returning to oestrus and conceiving after treatment (lambing rate: control = 86; hCG = 72; litter size: control = 1.44; hCG = 1.35). In conclusion, the data obtained in this study suggest that during the breeding season hCG may, by stimulating ovarian function, improve embryo survival in ewes conceiving at the first post-treatment oestrus. This effect, however was not observed in ewe lambs.     

SDS-PAGE electrophoretic property of human chorionic gonadotropin (hCG) and its beta-subunit

The microheterogeneity property of hCG with regards to its sialic acid contents resulted in variable mobility of the glycoprotein in SDS-PAGE. The intact hCG molecule is composed of two dissimilar subunits, namely alpha- and beta-subunits. The identification of hCG bands in SDS-PAGE was accomplished by the immunoblotting experiment, whereby the antibody directed toward the specific region of beta-subunit of hCG was used. The data shows that the different mobility of intact hCG was attributed to the different degree of desialylation of the glycoprotein. Nevertheless, unlike the intact hCG, the mobility of its beta-subunit was not affected by its variety sialic acid content. This characteristic of beta-hCG is beneficial when semi-quantification of total hCG is required. Quantification of hCG using the HPLC-reversed phase C18 analytical column is not possible as the glycoprotein was eluted in multiple fractions at different retention times. The identification of denatured hCG (HPLC eluted fractions) was carried out by immunoblotting experiment whilst immunoassay technique failed to detect its presence in any fraction.     

Selective radioimmunoassays for human luteinizing hormone (hLH) and human chorionic gonadotropin (hCG).

Highly specific radioimmunoassay systems were developed for measurement of hLH and hCG using antisera purified by affinity chromarography or simple adsorption to select the antibodies reacting specifically with either gonadotropin. Such systems permit specific measurement of lLH and hCG in samples containing both. These assays are suitable for various clinical and physiological studies, particularly, study of pituitary functions in the presence of chorionic or trophoblastic secretion.     

Concanavalin-A stimulates human chorionic gonadotropin (hCG) and hCG-alpha secretion by human choriocarcinoma cells

The plant lectin Concanavalin-A stimulates the secretion of human chorionic gonadotropin and free alpha subunit by cultured human choriocarcinoma cells in a dose dependent and time dependent manner. This stimulation is prevented by alpha-methyl-D-mannopyranoside, a Concanavalin-A specific hapten sugar. This is the first report of a lectin stimulating the secretion of a glycoprotein hormone. Since the stimulation likely occurs subsequent to interactions at the membrane level, Concanavalin-A may represent a probe for studying membrane-related events involved in the control of human chorionic gonadotropin secretion.     

Release of human chorionic gonadotropin (hCG) and its alpha-subunit (hCG-alpha) from perifused human placenta

The release of human chorionic gonadotropin (hCG) and its alpha-subunit (hCG-alpha) from the normal human placenta and the effect of some stimulatory agents on their release were studied in vitro using a perfusion system. Each perfusate was assayed for hCG and hCG-alpha in its own homologous radioimmunoassay systems. Both hCG and hCG-alpha were released from the placenta at any stage of gestation in our perfusion system. Much more hCG than hCG-alpha was released from the placenta in early gestation. By comparison, however, hCG-alpha increased gradually with the gestational age. The amount of hCG-alpha released was almost equal to that of hCG in the placenta in the 17th gestational week. After the 22nd gestational week, hCG-alpha was released in larger quantities than hCG, and about 10 times more hCG-alpha than hCG was released from the term placenta. These results were also confirmed by gel filtration of perfusates on a Sephadex G-100 column. hCG-alpha, compared with hCG, was present in excess in gel filtrated perfusates in the last two trimesters. By adding 1 mM dibutyryl cyclic AMP to the perifusion medium, the release of both hCG and hCG-alpha was stimulated significantly. Synthetic luteinizing hormone releasing hormone (LH-RH) at concentrations of 10 ng/ml and 100 ng/ml had no effect, but at a high concentration (1 microgram/ml), LH-RH stimulated the release of them. Moreover, mouse epidermal growth factor (EGF) stimulated not only the release of hCG and hCG-alpha but also their production, because both hCG and hCG-alpha levels rose progressively with the time course in the presence of EGF. The present studies demonstrate that the perifusion system of chorionic tissues is a useful method for investigating the release of hCG and its subunits in vitro.     

The effect of administering equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) post artificial insemination on fertility of lactating dairy cows

The objective was to evaluate the effect of equine chorionic gonadotropin (eCG) and hCG post artificial insemination (AI) on fertility of lactating dairy cows. In Experiment 1, cows were either treated with eCG on Day 22 post AI (400 IU; n = 80) or left untreated (n = 84). On Day 29, pregnant cows were either treated with hCG (2500 IU; n = 32) or left untreated (n = 36). Pregnancy and progesterone were evaluated on Days 29 and 45. In Experiment 2, cows (n = 28) were either treated with eCG on Day 22 (n = 13) or left untreated (n = 15) and either treated with hCG on Day 29 (n = 14) or left untreated (n = 14). Blood sampling and ultrasonography were conducted between Days 22 and 45. In Experiment 3, cows were either treated with eCG on Day 22 post AI (n = 229) or left untreated (n = 241). Pregnancy was evaluated on Days 36 and 85. In Experiment 1, eCG on Day 22 increased (P < 0.02) the number of pregnant cows on Day 29 (50.0 vs. 33.3%) and on Day 45, the increase was higher (P < 0.01) in cows with timed AI (41.2 vs. 6.5%) than in cows AI at detected estrus (50.0 vs. 37.8%). Pregnancy losses were reduced by eCG and hCG, but increased in cows that did not receive eCG but were given hCG (P < 0.01). Treatment with hCG tended (P < 0.06) to increase progesterone in control cows, but not in cows treated with eCG. In Experiment 2, hCG increased (P < 0.01) the number of accessory CLs on Day 35 (28.5 vs. 0.0%) and tended (P < 0.07) to increase progesterone. In Experiment 3, eCG increased the number of pregnant cows (P < 0.05) on Days 36 and 85, but only in cows with low body condition (eCG = 45.6 and 43.5%; Control = 22.9 and 22.9%). In conclusion, eCG at 22 days post insemination increased fertility, primarily in cows with low body condition and reduced pregnancy losses when given 7 days before hCG; hCG induced accessory CLs and slightly increased progesterone, but hCG given in the absence of a prior eCG treatment reduced fertility.     

Effect of desialylated human chorionic gonadotropin (hCG) on the bioactivity of rat Leydig cells

Human chorionic gonadotropin is a glycoprotein hormone that, like LH, stimulates steroidogenesis in gonadal cells. Using a desialylation process, 95 per cent of the sialic acid residues from an intact standard hCG molecule were eliminated and then the electrophoretic properties and the bioactivity of the desialylated hCG were determined. Using rat Leydig cells as a biological model, the binding affinity to LH receptors of Leydig cell membranes, steroidogenic activity and second messenger production were studied. The results indicate that the loss of sialic acid from the hCG molecule slightly increases the binding activity to LH receptors and results in steroidogenic activity with an increased ED₅₀. Cyclic AMP production was significantly reduced however and arachidonic acid release was not observed. Several possible mechanisms that could explain these results are discussed. © 1998 John Wiley & Sons, Ltd.     

Effects of human chorionic gonadotropin (hCG) and handling stress on spermiation of silver perch Leiopotherapon plumbeus (Kner, 1864)

This study determined the effect of human chorionic gonadotropin (hCG) and handling stress on the spermiation and milt response of silver perch Leiopotherapon plumbeus based on the measurement of spermatocrit, sperm density, and milt production. Compared to saline‐injected fish, the mean spermatocrit (or packed sperm) of hCG‐treated fish was significantly lower at 18 h (47.9%) and 30 h (40.2%) post‐injection while mean sperm density was significantly lower at 30 h post‐injection (3.6 × 10⁶ cells μl^?1) but not at 18 h. At 18 h (1.8 μl g‐BW^?1) and 30 h (2.5 μl g‐BW^?1) post‐injection, mean milt production of hCG‐treated fish was significantly higher than in the saline group. Milt consistency was also thinner in the hCG‐treated group. Mean sperm density of handled fish (18.0 × 10⁶ cells μl^?1) was significantly lower than control fish (23.4 × 10⁶ cells μl^?1). However, mean sperm density of handled plus saline‐injected (16.2 × 10⁶ cells μl^?1) and handled plus hCG‐treated fish (8.4 × 10⁶ cells μl^?1) was significantly lower than in the control goup. Having thicker milt consistency, mean spermatocrit and milt production of handled (77.5%; 1.1 μl g‐BW^?1, respectively) and handled plus saline‐injected fish (75.4%; 1.1 μl g‐BW^?1, respectively) were not significantly different from the control fish (76.2%; 1.3 μl g‐BW^?1, respectively). Handled plus hCG‐treated fish had the lowest mean sperm density (8.4 × 10⁶ cells μl^?1) and spermatocrit (54.7%), but had the highest mean milt production (5.5 μl g‐BW^?1) among the treatment groups. These results demonstrate that the hCG injection effectively induces spermiation and milt expression and that handling‐related stress negatively affects such responses. The spermatocrit method may be used to assess the spermiation and milt response of silver perch.     

Effect of a partially desialylated human chorionic gonadotropin preparation (Desialo hCG) on ovarian function

Six patients with unexplained infertility were administered a partially desialylated hCG preparation (Desialo hCG). 5000 and 10000 IU of this preparation were given as a single IM dose, following the administration of hMG-Pergonal. The circulatory half-life (t 1/2) of Desialo hCG was found to be 42.6 hours, which is similar to the t 1/2 of 35.6 hours previously reported for a hybrid hCG preparation. The t 1/2 values were shorter than the t 1/2 of 65.3 hours estimated for commercial hCG administered by the same route. In spite of the similarities in t 1/2 values between the two preparations, serum progesterone levels were significantly increased 48 to 96 hours after the administration of Desialo hCG, and only 8 to 10 hours after the administration of the hCG hybrid. The difference in response may reflect differences in receptor occupancy at the ovarian level. Large scale testing of preparations with half-lives approaching the t 1/2 of the physiological hormone, hLH, should be carried out in order to determine if the risk of overstimulation and/or multiple pregnancies could be reduced thus, allowing for a safer therapeutic modality in patients pre-treated with hMG.     

Effects of human chorionic gonadotropin on luteal blood flow and progesterone secretion in cows and in vitro-microdialyzed corpora lutea

To check human chorionic gonadotropin (hCG) effects on luteal blood flow (LBF) and progesterone (P₄) synthesis, six cows received either 3000 IU hCG or saline (NaCl) on Day 7 (Day 1 = ovulation) during two estrous cycles. Plasma P₄ and LBF were measured before (0 h) and up to 48 h after treatment. Luteal blood flow increased by 51% (P < 0.05) at 1 h after hCG administration and returned to baseline levels thereafter. Plasma P₄ levels were increased from pretreatment levels by 30% at 1 h (P = 0.05) and 81% at 48 h (P = 0.02) after hCG treatment. In contrast, NaCl did not cause changes in LBF and P₄ (P > 0.05). Additionally, central and peripheral parts of 14 abattoir-derived corpora lutea of the mid-luteal phase (Day 8 to 12) were perfused with Ringer solution in an in vitro microdialysis system, supplemented with 50 or 150 IU/mL hCG for 1 h. Application of 50 IU/mL hCG showed no influence on P₄ response (P > 0.05) in both central and peripheral parts, whereas 150 IU/mL hCG resulted in an increase of P₄ synthesis (P = 0.002) in the central parts only. In vivo, hCG provoked an immediate and long-term rise in P₄ but only a temporary elevation of LBF. Luteal blood flow itself does not seem to be the exclusive cause for an increase in P₄, because the in vitro data clearly showed direct effects of hCG on P₄ secretion. Interestingly, different P₄ secretion patterns could be found between central and peripheral parts of the corpus luteum in both control and hCG perfused corpora lutea.     

Fertility of dairy cattle treated with human chorionic gonadotropin (hCG) to stimulate progesterone secretion

Two experiments were conducted to determine if progesterone secretion and fertility would be affected by administration of human chorionic gonadotropin (hCG) before or after the first insemination. In Experiment 1, 48 Holstein heifers received 1000 IU of hCG or 1 ml of saline on Days 2, 3, and 4 of an estrous cycle. They were inseminated at the subsequent estrus. In Experiment 2, 110 Jersey and 105 Holstein cows received a single injection of 5000 IU of hCG or 5 ml of saline on Day 3 after estrus. These cows were first inseminated either at the estrus immediately preceding treatment or at the subsequent estrus. In both experiments, blood samples for determination of progesterone were collected thrice weekly for 3 to 4 wk following treatment. In Experiment 1, progesterone concentrations during mid-cycle were higher in hCG-treated heifers than in saline-treated controls. Treatment with hCG resulted in an 11% increase in the first service conception rate (P < 0.48). In Experiment 2, hCG-treated cows displayed higher progesterone secretion during mid-cycle than saline-treated herdmates. The conception rate of cows inseminated prior to hCG-treatment was not affected by treatment, but cows inseminated after treatment had a marginally lower fertility rate. The conception rate of cows receiving a repeat insemination following hCG treatment was higher than for the controls. We conclude that treatment with hCG did not improve the conception rate at the first insemination, but it may be beneficial for cows that require a repeat service.     

Effects of hCG on folliculogenesis and fecundity in mink (Mustela vision Schreb)

The endogenous hormonal response obtained after reproductive organs are challenged by exogenous hormones is increasingly being used to predict presence of functional reserves and to apply this information to improve efficiency of managed breeding programs. With that in mind, the aim of the present study was to investigate the effect of a single treatment with hCG on folliculogenesis and fertility in standard 7-month-old mink females. The extent of stimulation following treatment was determined by examining patterns of vaginal smears. Characteristics of each cycle stage were: estrus, preponderance of cornified epithelial cells; proestrus, polygonal, elongate epithelial cells; anestrus, parabasal, intermediate and leucocyte cells. Smears exhibiting a mixed population of cells were categorized as being in transition between adjacent stages anestrus–proestrus or proestrus–estrus. The initial evaluations were done on Day 6 after hCG treatment. Histomorphometric examination of ovaries and uteri was done during seasonal anestrus (November) and in the breeding season (March). Vaginal cytology patterns were correlated with changes in folliculogenesis. A mean of 1.3 mature (Graafian) follicles were counted during estrus, while the mean number seen during anestrus, anestrus–proestrus and proestrus, were 0.4, 0.3 and 1.0, respectively. During the breeding season, in females that were not treated, the numbers of growing follicles decreased and maturing follicles increased, whereas females that came in estrus after treatment with hCG in November had increased numbers of both growing and maturing follicles. Fertility after breeding in hCG-treated females was increased by 9.2% (P<0.05) as compared to untreated females. Females showing the highest fertility rise (27%) were predominantly in the group that showed estrus after hCG treatment. We conclude that monitoring the response of the mink reproductive system to hCG stimulation in November may be a useful tool for identifying females of high fertility in the spring.     

Epitope mapping of the receptor-bound agonistic form of human chorionic gonadotropin (hCG) in comparison to the antagonistic form (deglycosylated hCG).

On the surface of free human chorionic gonadotropin (hCG), we can distinguish with our panel of monoclonal antibodies (MCA) 14 topographically distinct epitopes (designated alpha 1 - alpha 5, beta 1 - beta 5, alpha beta 1 - alpha beta 4, depending on the subunit they are attached to). Only 2, i.e. the adjacent beta 3 and beta 5 epitopes, of these 14 are accessible to 125I-labeled MCA binding, when hCG is first allowed to bind to the rat testis hCG receptor. This result indicates that the agonist hCG assumes a defined orientation in its receptor-bound state and that, except for that small area comprising the beta 3 and beta 5 epitopes, most of its surface is masked by the hCG receptor. We therefore asked whether the competitive antagonist deglycosylated hCG (degly-hCG), which, when free, is antigenically (as to number and topography of epitopes) indistinguishable from native hCG, would interact with the receptor differently, that is, in a way that can be discerned by this epitope accessibility paradigm. Here we describe that on receptor-bound degly-hCG the beta 3 and beta 5 epitopes were concealed as were all other epitopes. This observation, together with finding the receptor affinity of degly-hCG to be 4 times higher than that of native hCG, suggests that degly-hCG assumes a signal transduction-incompetent ligand orientation and at the same time interacts with the receptor more intensively, i.e. establishes additional ("antagonist accessory") protein-protein contacts besides those involved in agonist binding. It thus appears that the carbohydrate moieties function to prevent formation of such accessory contacts.     

Serum and cerebrospinal fluid human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP) in intracranial germ cell tumors

We report a retrospective study on serum and cerebrospinal fluid (CSF) alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (betahCG) determination in a series of 30 patients bearing intracranial germ cell tumors. At diagnosis five patients had high serum and CSF AFP levels. No patient had positive serum AFP and negative CSF AFP or vice versa. Twelve of 30 patients had serum betahCG levels above 5 mlU/mL, eight had high betahCG only in CSF, and ten were completely negative. During treatment and follow-up both markers were accurate indicators of the response to therapy, decreasing rapidly and often becoming normal already after the first phase of treatment. We conclude that these two markers, and mostly betahCG, may be useful in the diagnosis and monitoring of the response to therapy of patients with intracranial germ cell tumors.     

Inhibitory effect of human chorionic gonadotropin (hCG) on HIV-1 transmission from lymphocytes to trophoblasts.

It has been demonstrated that human chorionic gonadotropin (hCG) inhibits HIV production in vitro, suggesting that this soluble placental glycoprotein can control viral replication and spread in vivo. hCG--the major product of fetal trophoblasts--was tested on an in vitro model consisting of choriocarcinoma-derived ENAMI trophoblasts exposed to HIV-infected MOLT-4 lymphocytes. The results show a U-shaped antiviral dose-effect and suggest that hCG may contribute to protection against intrauterine transmission of HIV-1.     

Effects of dietary sewage solids on second-generation ewes fed an experimental diet from weaning through two reproductive cycles

Eighteen fine-wool ewe lambs produced by mature, conventionally fed dams and 21 similar offspring from sewage-fed ewes were randomly allotted at weaning to one of two groups. Half of the lambs from each maternal diet group received a conventional (18% protein) diet during the growing phase while the remainder was fed the conventional diet plus 7% undigested, irradiated sewage solids (18% protein). At the end of the 147-day growing period and just before a fall breeding season, conventionally fed ewe lambs were switched to a control diet (12% protein) suitable for mature ewes and sewage-fed ewe lambs began receiving the control diet plus 7% sewage solids. Animals received these diets for two years. Maternal sewage consumption did not influence performance of F₁ ewe lambs. By the beginning of the first breeding season, controls were heavier (P<0.01) than were animals receiving sewage solids (51.7 and 44.5 kg, respectively). Similarly, only 75% of sewage-fed ewe lambs exhibited estrus during their first breeding season compared with 94.7% of controls (P<0.10). Conception rate (40.0 and 84.2%, respectively) and lambs born per ewe exposed (0.4 and 0.89, respectively) were also lower (P<0.05) in animals receiving sewage solids than in controls. During the second reproductive cycle, conception rate as well as lambs born per ewe exposed was comparable (P>0.10) between the two groups. Offspring from the sewage-fed ewe lambs, however, weighed less (P<0.05) at weaning than did lambs produced by control animals. Results indicate that a diet containing 7% sewage solids may not be suitable for preparing ewe lambs to go into the breeding flock; once mature size is attained, however, reproductive performance is not hampered by sewage feeding.