Human chorionic gonadotropin/luteinizing hormone receptor expression in the adult rat spinal cord

The adult and fetal rat brain contains human chorionic gonadotropin/luteinizing hormone (hCG/LH) receptors, that are functional in mediating the neurotropic, neuroendocrine and behavioral actions of gonadotropins. We hypothesized that the spinal cord also contains these receptors. We have now demonstrated by in situ hybridization, immunohistochemistry, and topical autoradiography that the adult rat spinal cord expresses hCG/LH receptors. Positive cells included motoneurons, interneurons and/or glia in the intermediate and ventral gray matter, interneurons and/or glia in the dorsal gray matter, and oligodendrocytes or astrocytes in the white matter. The receptors were able to bind an appropriate ligand, (125)I-hCG. The functional significance of these receptors in the spinal cord is unknown, but we can speculate that they may be neurotrophic in function.     

Human chorionic gonadotropin: a secretory hormone.

There are several physiological and pathophysiological situations where there is an apparent fluid flux across plasma membranes at the time when human chorionic gonadotropin (hCG) levels are high. These fluxes may take the form of a fluid loss from gastrointestinal tract (e.g. emesis/hyperemesis gravidarum) or accumulations in enclosures (e.g. amniotic fluid or hydatidiform mole). What is not obvious though is whether hCG is the cause of these fluid fluxes. Although glycoprotein hormones like hCG are mainly hormonogenic, their action in the latter process involves the efflux or conductance of halide ions. Since the basis of fluid secretion is an active efflux of ions such as chloride stimulated by a humoral agent, accompanied by a passive diffusion of water across a cell wall, I hypothesize that hCG is also a secretory hormone and responsible for fluid fluxes in the above and other clinical situations.     

Human prolactin release induced by follicle stimulating hormone, luteinizing hormone and human chorionic gonadotrophin

Plasma prolactin levels rise in stimulated cycles. To clarifythe effects of gonadotrophin on the lactotrophs, three studieswere performed. First, plasma concentrations of prolactin duringclomiphene citrate (CC)-human menopausal gonadotrophin (HMG)-humanchononic gonadotrophin (HCG) treatment of women enrolled forin-vitro fertilization (IYF) were compared with those duringHMG-HCG administration while under pituitary suppression witha gonadotrophin releasing hormone (GnRH) analogue (buserelin).Women suppressed with buserelin had higher basal levels of PRLin plasma (14.4 ± 4.3 nglml versus 6.9 ± 1.4 ng/ml,P<0.001). Only buserelin-suppressed women showed a significantrise in plasma prolactin before HCG administration, while bothpatient groups had marked prolactin peaks after HCG injection.This peak was higher in the buserelin group (71.9 ± 50.7ng/ml versus 52.6 ± 29.7 ng/ml). The second study showedthat plasma levels of prolactin of 6 post- menopausal womenwere significantly increased 48 h after an injection of 5000IU HCG, i.m. (24.9 ± 17.4 ng/ml versus 12.4 ±6.2 ng/ml P<0.05). Third, plasma prolactin was studied in5 women over 30 days after surgical castration. An upward trendwas observed similar to that of endogenous gonadotrophin, withthe change in prolactin values closely correlating with thechange in concentrations of follicule stimulating hormone (P<0.005).All these findings suggest that human gonadotrophins stimulatelactotrophs.     

Antigenic regions on the beta chain of human chorionic gonadotropin and development of hormone specific antibodies

Five peptides corresponding to four regions of the beta chain of human chorionic gonadotropin (hCG), were synthesized, purified and characterized. The four regions studied were selected on the basis of sequence differences between the beta chain of hCG (beta hCG) and the beta chains of related hormones. The peptides were found to bind rabbit and mouse anti-hCG antibodies as well as rabbit anti-beta chain antibodies, but did not bind antibodies against the alpha chain or against other hormones. All the peptides, even in their free form, were able to elicit high titer antisera in both rabbits and mice. In all cases, anti-peptide antisera bound to the immunizing peptide as well as to the native hCG and the isolated beta chain. These anti-peptide antisera did not bind to unrelated peptides, the alpha chain of hCG or to other hormones with very similar beta chains such as human luteotropic hormone (hLH), ovine luteotropic hormone (oLH) and equine chorionic gonadotropin (eCG). Since the areas represented by these peptides elicit antibodies that are specific for human beta hCG, they can formulate the basis for the development of discriminatory reagents for the beta chain of hCG.     

Ultrasensitive immunoradiometric assay for chorionic gonadotropin which does not cross-react with luteinizing hormone nor free beta chain of hCG and which detects hCG in blood of non-pregnant humans

We have developed a sensitive, non-competitive, two-monoclonal antibody, sandwich-type or immunoradiometric assay for human chorionic gonadotropin (hCG) which shows no cross-reaction with the free beta chain of hCG nor with human luteinizing hormone (LH). In the assay procedure, two, highly selected monoclonal antibodies reacted in solution with hCG to be quantified. One antibody was covalently conjugated to biotin. This antibody was specific for the beta subunit of hCG, and showed no reaction with LH nor the alpha subunit. The second antibody was labelled with 125I and was specific for intact hCG and LH, showing no cross-reaction with beta hCG nor the alpha subunit. The separation system was a polystyrene ball conjugated with biotin. This ball bound via an avidin bridge the monoclonal 'sandwich' containing hCG. Counts per minute bound to the ball were directly proportional to the amount of hCG present. The assay was specific for whole hCG and showed no reaction with beta hCG, beta LH, intact LH nor the free alpha subunit. Sensitivity was adequate to detect 'hCG-like' material in all post menopausal women and, when single samples were obtained, in over 2/3 of normal men. When multiple samples were obtained, 'hCG-like' material was detectable in all eugonadal adults studied.     

Bioneutralization capacity of the antibodies generated in women by the beta subunit of human chorionic gonadotropin (beta hCG) and beta hCG associated with the alpha subunit of ovine luteinizing hormone linked to carriers.

Data is presented on the bioneutralization capacity per unit immunoactivity of 30 serum samples of women immunized with the beta-subunit of human chorionic gonadotropin (beta-hCG) or beta hCG associated noncovalently with the alpha-subunit of ovine luteinizing hormone (alpha-oLH), to form a heterospecies dimer (HSD), which were linked to carriers. The bioassays utilized were inhibition of radioiodinated hCG binding to rat testicular receptors in vitro and the inhibition of hCG induced testosterone production in mice. In both assays, antisera of women immunized with the HSD had a bioactivity to immunoactivity ratio that was about 25% higher, on an average, than antisera of women immunized with beta-hCG, suggesting a better bioneutralization capacity of sera raised by the HSD in women.     

Luteinizing hormone/human chorionic gonadotropin receptors in myometrium and their role in uterine motility

The object of this paper is the existence of LH/hCG receptors in female uterine tissue. Specific and high-affinity binding sites for LH are present in the pig and rabbit uterus. Estradiol promoted the synthesis of LH receptors in porcine myometrium. Stimulation of LH receptors with hCG in estrogen-primed tissue had a quiescence effect on myometrial contractility in vitro. The physiological role of uterine LH receptors in maintenance of myometrial quiescence is discussed.     

Influence of abnormal structure beta chain of luteinizing hormone on endocrinological kinetics of luteinizing hormone and gynecologic diseases

With recent progress in endocrinology and in procreation physiology, the importance of kinetics of pituitary gonadotropin has been increasing, and the measurement method has been improved. In the present study, however, we found inconsistency in measured LH values between IRMA (SPAC-S LH) as the conventional method and CLEIA (IMMULYZE LH) as the newly developed method. The inconsistency between the SPAC-S LH value and the IMMULYZE LH value was observed in 10.0% of the healthy group and in 12.5% of the patient group. The cause of this discrepancy was due to a reaction of the SPAC-S LH of the intact LH monoclonal antibodies to the LH with the abnormal structure beta chain by two point mutation in the LH beta gene. The response of LH-RH test varied depending on the measurement reagent of LH in patients who had the LH with the abnormal structure beta chain, which made it difficult to determine the lesion and histological grading regarding the ovulation mechanism. Therefore, in patients with abnormal beta chain, an accurate treatment protocol was indeterminate. In this study, although a relationship between various gynecological diseases and the point mutation of LH was not clarified, we suggest that LH of the abnormal structure beta chain may cause excessive secretion in the early stage, and lead to some effect on physical activities.     

Human chorionic gonadotropin expression in lung, breast, and renal carcinomas

Conflicting results have emerged from studies that have examined nontrophoblastic tumor tissue for the presence of human chorionic gonadotropin (hCG) by immunoperoxidase techniques. We evaluated 11 lung carcinomas, ten breast carcinomas, and ten renal cell carcinomas for the presence of immunoreactive hCG by the avidin-biotin-horseradish peroxidase method. The hCG was found in 36% (4/11) of lung tissues, 10% (1/10) of breast tumors, and none of renal tumors. These values are lower than earlier reports for the frequency of detected hCG in the tumor tissue, but they are similar to several more recent studies. The possible reason for these discrepancies are discussed.     

Apoptosis and tumor inhibition induced by human chorionic gonadotropin beta in mouse breast carcinoma

For many breast cancer patients, human chorionic gonadotropin beta (hCGβ), which is a subunit of a hormone produced by the trophoblast and is essential for maintaining pregnancy, is expressed in the breast cancer cells. However, the mechanism as to how the CGβ in cell affects the cancer development is not very clear. Mouse breast carcinoma 4T1 with stably hCGβ expression (4T1-hCGβ) was established and transplanted into the Balb/c mouse abdominal mammary gland. hCGβ suppressed breast cancer cell viability in vitro, and dramatically inhibited tumor growth and attenuated tumor vessel formation in vivo. An 86–88% reduction in tumor volume in animals injected with breast cancer expressing hCGβ, as opposed to those injected with breast cancer without hCGβ expression, was observed. The production of p21 was promoted by hCGβ, whereas the Cdk2 was decreasing. These indicate that p21 signal pathway is involved in this process. Significant apoptosis was also detected in hCGβ-expressing breast cancer cells as well as the enhancement of Bax protein expression. Moreover, hCGβ blocked the blood vessels formation by inhibiting the expression of MMP9 and VEGF. Further hormone secretion analyses show that the anti-tumor activity induced by hCGβ is not related to the endocrine function.     

Monoclonal antibodies against immunodeterminants associated with the alpha and beta subunits of human chorionic gonadotropin

Spleen cells of BALB/c mice immunized with human chorionic gonadotropin (HCG), a glycopeptide hormone composed of two nonidentical alpha and beta subunits, were fused with NS-1 mouse myeloma cells. Two hybrid cell lines, cone PC2 and clone PD3 secreting monoclonal antibodies (McAb) to HCG were isolated. With the aid of a double antibody radioimmunoassay it was established that PC2-McAb recognizes an immunodeterminant associated with beta-HCG subunit, whereas, PD3-McAb recognizes an epitope present on the alpha-HCG subunit. Both monoclonal antibodies showed an affinity constant of approximately 5 X 10(10) L/M. Because of these immunological characteristics, only PC2-McAb specifically reacts with HCG and shows cross-reactivities of less than 0.1% to other related human glycopeptide hormones. On the other hand, using a hemagglutination test based on antibody induced agglutination of sheep red blood cells coated with HCG, it was shown that only PD3-McAb is capable of inducing a positive reaction, although both monoclonal antibodies have a similar binding capacity to the coated cells. The potential of these two new monoclonal reagents for the qualitative detection and quantitative determination of HCG in human biological fluids is discussed.     

Modulating impact of human chorionic gonadotropin hormone on the maturation and function of hematopoietic cells

hCG hormone is a naturally occurring, immune-modulating agent, which is highly expressed during pregnancy and causes improvements of some autoimmune diseases such as multiple sclerosis and Crohn's disease. Little is known about its immune-modulating effects. This study in MNCs of women who received hCG as preconditioning prior to IVF demonstrates that hCG increases anti-inflammatory IL-27 expression and reduces inflammatory IL-17 expression. In addition, we found increased IL-10 levels and elevated numbers of Tregs in peripheral blood of women after hCG application. Rejection of allogeneic skin grafts was delayed in female mice receiving hCG. We conclude that hCG may be useful for the induction of immune tolerance in solid organ transplantation.