Presence Of Human Chorionic Gonadotropin Research Articles

MATURATIONAL CHANGES IN SHEEP OVARIAN FOLLICLES: GONADOTROPHIC STIMULATION OF CYCLIC AMP PRODUCTION BY ISOLATED THECA AND GRANULOSA CELLS

Theca and granulosa tissues isolated from sheep ovarian follicles of different sizes were incubated in the presence of human chorionic gonadotrophin (HCG; 5 IU/ml) or follicle stimulating hormone (FSH; 5 microgram NIH-FSH-S11/ml) for 40 min. Changes in the total amounts of cyclic 3',5'-adenosine monophosphate (cAMP) were used as an index of the responsiveness of these preparations to the hormones. Thecal tissue of both large (4-6 mm in diameter) and small (1-3 mm) follicles responded similarly to gonadotrophins. Granulosa cells from small follicles failed to respond to stimulation by HCG. FSH, however, consistently increased cAMP production in comparison with controls or cells treated with HCG. Granulosa cells of large follicles responded to both HCG and FSH.

Species differences in steroidogenesis following the in vitro incubation of decapsulated testes.

ABSTRACT Decapsulated testes of rats, guinea pigs and rabbits were incubated with or without labelled precursors and the steroids formed under various experimental conditions were analysed. Also a decapsulated human testis was incubated with labelled acetate. Cholesterol, testosterone and androstenedione were isolated in a radiochemically homogeneous form following the incubation of carbon-14-labelled sodium acetate with decapsulated testes of all 3 animal species. No other labelled steroid was detected following the incubation of rat testes. Guinea pig testes also converted labelled acetate to pregnenolone. Rabbit and human testes converted labelled acetate to cholesterol, pregnenolone, dehydroepiandrosterone, androstenediol, testosterone and androstenedione. When decapsulated testes of rats, guinea pigs and rabbits were incubated with carbon-14 labelled pregnenolone as a precursor, radiochemically homogeneous progesterone, 17-hydroxypregnenolone, dehydroepiandroster-one, androstenediol, androstenedione and testosterone were isolated in each experiment. Using radioimmunoassay techniques, preformed steroids together with steroids formed from endogenous precursors were analysed following the incubation of rat, guinea pig and rabbit testes in the absence and in the presence of human chorionic gonadotrophin (HCG). Marked (seasonal?) variations were observed between the results of experiments conducted at different times. Incubation of guinea pig testes in the absence as well as in the presence of HCG resulted in a major increase in pregnenolone levels. No such finding was encountered when rat and rabbit testes were incubated. The addition of HCG resulted in at least a 10-fold increase in testosterone formation by the testes of all three species. The addition of HCG to the incubation medium induced a marked rise in dihydrotestosterone levels in the rabbit testes but had no effect whatsoever on the levels of this steroid in guinea pig testes. It is concluded that considerable species differences exist in the steroid metabolism of decapsulated testes incubated in vitro.

Production of specific antisera for radioimmunoassay of human luteinizing hormone (LH) in the presence of human chorionic gonadotropin (hCG).

A specific radioimmunoassay for LH, which measures plasma LH in the presence of human chorionic gonadotropin (hCG) is described. Rabbits were immunized with highly purified native LH. One of the antisera with a difference in its reactivity against LH and hCG was further purified by affinity chromatography on a column with hCG coupled to Sepharose 4B. The adsorbed antiserum and 125I-LH was used in a double antibody assay. The LH standard (MRC 68/40) efficiently inhibited the binding of 125I-LH, and the standard curve showed a sensitivity of 0.5 ng/ml in the sample. hCG up to 10 000 ng/ml did not inhibit the binding of 125I-LH. The plasma level of LH in pregnant women in the first trimester was low (1.3 +/- 0.1 ng/ml). When LH was measured in fertile or menopausal women with or without stimulation with LH/FSH releasing hormone (LH-RH)X the results agreed to those found with our conventional LH-assay based on antiserum against hCG.

Relationship between Concentrations of Human Chorionic Gonadotrophin (HCG) in Maternal Plasma, Amniotic Fluid and Fetal Cerebrospinal Fluid

The cerebrospinal fluid (CSF) of 14 fetuses of 13–24 weeks of gestation has been assayed for the presence of human chorionic gonadotrophin (HCG). The results demonstrated that small amounts of HCG were present in the fetal CSF and showed highest values at 13 weeks, gradually falling to very low values by 19 and 24 weeks of gestation. No correlation appeared to exist between HCG concentration in maternal plasma and HCG concentration in fetal CSF, whereas a significant correlation could be demonstrated between HCG concentration in amniotic fluid and HCG concentration in fetal CSF. It may also be suggested that the blood brain barrier for HCG is incompletely developed in the fetus but this problem requires further investigation.

Suppression of Antitumor Lymphocyte Mediated Cytotoxicity by Human Chorionic Gonadotropins

The effect of human chorionic gonadotropin on the in vitro cytotoxicity of lymphocytes against human transitional cell carcinoma cells was studied in 9 patients using the microcytotoxicity assay. Lymphocytes from 6 patients were cytotoxic against transitional cell carcinoma cells. However, in the presence of human chorionic gonadotropin the cytotoxicity of these lymphocytes against transitional carcinoma cells was diminished. Human chorionic gonadotropin alone or in combination with non-cytotoxic lymphocytes did not change the growth of target cells and human chorionic gonadotropin did not have a direct toxic effect on lymphocytes alone. These results demonstrate that human chorionic gonadotropin can inhibit the cytotoxic action of lymphocytes against human tumor cells in vitro. Human chorionic gonadotropin may contribute to the poor prognosis associated with certain human chorionic gonadotropin-secreting human tumors.

Ultrastructural localization of chorionic gonadotropin in human term placenta.

Human chorionic gonadotropin (HCG) was localized in human placenta at the ultrastructural level by an immunocytochemical method which linked the antigen HCG to a peroxidase label through the antigen-antibody reactions of an immunoglobulin-peroxidase bridge. Material on the maternal surface of the apical plasma membrane and in the cisternae of rough endoplasmic reticulum of the syncytiotrophoblast displayed strong immunostaining for HCG and the outer surface of the basal plasma membrane appeared equivocally immunoreactive. Lamellae and vesicles of the Golgi complex of the syncytium lacked electron-opaque reaction product indicative of immunostaining for HCG. Deposits of peroxidase reaction product in the large variety of cytoplasmic dense granule varied from negligible to abundant in immunostained and in control specimens alike and, accordingly, the large granules appeared to contain intrinsic peroxidase but not HCG. The question of the immunoreactivity of the small variety of cytoplasmic dense granule was not conclusively settled, but the occurrence of reactive and unreactive small granules in both immunostained and control specimens weighed against the presence of HCG in these rather infrequent granules. The cytotrophoblast lacked evidence of immunoreactivity.

Biochemical studies in a patient with chromatin-negative klinefelter's syndrome

The metabolism of [ 3H]dehydroepiandrosterone and [4- 14C]progesterone by homogenates of testicular tissue obtained from a patient with the features of chromatin-negative Klinefelter's syndrome has been studied in vitro. In these conversion studies, [ 3H] Δ 5-androsten-3 β,17 β-diol was the only metabolite detected in the incubates. When minced testicular tissue was incubated, a small amount of testosterone was produced in vitro, and no significant rise occurred in the presence of human chorionic gonadotrophin. By contrast, the patient's plasma testosterone level was below the normal male range, and showed a marked rise following administration of human chorionic gonadotrophin. These studies suggest a 3-β-hydroxysteroid dehydrogenaseisomerase deficiency in this disorder and demonstrate that the capacity of the testis to secrete testosterone in vitro is extremely small and unresponsive to human chorionic gonadotrophin.