Constitutivity of the HCG-receptor protein in the testis of rat and man

Reduced level of sex-specific antigen (H-Y antigen) on lymphocytes in some patients with bilateral cryptorchidism

Sex-specific (Sxs) antigen on the surface of nucleated cells from normal human males seems to be essential for the formation of testes. The relative quantity of the antigen on lymphocytes was evaluated by absorption experiments in a complement-dependent cytotoxicity test or in an ELISA technique using antisera against Sxs antigen produced by immunization of female rats. Lymphocytes from 13 normal males were Sxs-antigen positive, and cells from 12 normal females were characterized as Sxs-antigen negative. However, in the testing of lymphocytes from nine boys with bilateral cryptorchidism, only six revealed a normal male absorption pattern, whereas the antigen level on cells from three boys, all of them with normal karyotype, was reduced compared with the normal male level. No correlation between Sxs-antigen level and testosterone response after treatment with hCG could be demonstrated.

Characterization of gonadotropin-sensitive adenylate cyclase activity in human testis: uncoupling of the receptor-cyclase complex by specific hormonal antagonist

Basal and gonadotropin stimulated adenylate cyclase activity was assessed in testicular tissues obtained from men (20-80 years). A disparity was observed in the gonadotropin responsiveness of the human testicular adenylate cyclase system to hFSH and hCG stimulation. Of the tissues analyzed, 61% were FSH responsive and 22% showed low response to hCG. Forskolin, a diterpene which activates adenylate cyclase by a receptor independent mechanism, stimulated adenylate cyclase activity in the gonadotropin unresponsive tissues. This suggests that the tissue unresponsiveness is due to an uncoupling of the catalytic subunit of the adenylate cyclase. Several functional properties of the FSH responsive human testicular adenylate cyclase were investigated. hFSH and oFSH stimulated the enzyme activity in a concentration dependent manner. However, the hormone (DG-oFSH) in which 80% of the carbohydrate residues had been removed was inactive, despite its good binding ability to the FSH receptor. hFSH stimulated adenylate cyclase activity was inhibited by DG-oFSH but not by DG-hCG (deglycosylated hCG). The data demonstrates the existence of specific FSH and LH(hCG) receptors in human testicular membranes. The FSH receptors in some tissues are coupled to adenylate cyclase. The link between the FSH receptor and adenylate cyclase may be uncoupled in the presence of the deglycosylated form of oFSH resulting in a loss of hormone response.

Receptors for luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the human undescended testis and the effect of hCG-treatment

Human testis tissue contains specific receptors for luteinizing hormone (LH) and follicle stimulating hormone (FSH) with Ka's of 1.5 and 1.6 X 10(9) M-1, respectively. Specific binding of [125I]hLH and [125I]hFSH was studied in testicular biopsies from 33 boys (4-16 years of age) with undescended testes and in 2 adult men with normally descended testes. Ten of the boys were treated with human chorionic gonadotrophin (hCG) and operated 1-4 days after the last injection. Samples from each testis were taken for histological evaluation. Specific binding of LH in biopsies from pre-pubertal boys (stage I) was low and differentiated Leydig cells could not be identified histologically. In later pubertal stages the LH binding increased and differentiated Leydig cells could now be recognized. hCG-treatment caused a highly significant increase (P less than 0.001) in the binding of LH without affecting FSH binding. The highest binding of FSH occurred during the onset of puberty. Treatment with hCG did not cause premature differentiation of Sertoli cells or germ cells, but appeared to stimulate Leydig cells.

Effect of neuraminidase on luteinizing hormone/chorionic gonadotrophin binding to the ovarian and testicular membranes from different mammalian species

After treatment of the ovarian and testicular membranes from several mammalian species an elevation in the specific binding of human [125I]-labelled CG could be observed. With the assumption that this effect is due to sialic acid-masked receptors, the presence of such receptors seem to be a common property of most mammalian gonads. An interesting observation was the abnormally high hormone binding capacity of the Syrian hamster ovary, as compared to other hamster species, and the lack of a neuraminidase effect in the ovary of the Syrian hamster.

Pituitary gonadal function in infertile men with varicocele

Infertile men with varicocele or idiopathic infertility were compared with a control group. Spermocytograms were taken and the following radioimmunological plasma analyses carried out: testosterone, FSH and LH before and after 50 micrograms LRH, Prolactin (PRL) before and after 200 micrograms TRH; in addition, 8 patients with varicoceles and 3 controls received LRH intravenously (0.4 microgram/min.) for 4 hours. The binding of [125I] human chorionic gonadotrophin (hCG) to testicular tissue obtained by biopsy from 10 infertile men was also investigated. Of the parameters studied, no differences were found between the unilateral or bilateral varicoceles. In the two groups of infertile men, sperm motility and percentage normal forms were similar and significantly lower than in controls. As compared to the controls, in the groups of infertile men, basal LH and testosterone levels were no different but basal FSH levels was increased, basal PRL was higher (p less than 0.05) in the varicocele group. Responses of the LH, FSH and PRL to LRH and TRH stimulations were generally higher in infertile men than in controls. As compared to the idiopathic infertile men, testosterone levels and responses of plasma FSH to LRH injection were lower in varicocele group. Moreover, in infertile men with varicocele, age was correlated negatively with sperm motility and testosterone level and it was correlated positively with LH response to LRH injection. For each patient, testicular tissue was able to specifically bind [125I]hCG, but in some cases of varicoceles, hCG binding capacity was different in the two testes and seemed higher than that observed in men with obstructive azoospermia. These results suggest: 1) dysfunction in both spermatogenesis and Leydig cells with a compensatory hyperfunction of the pituitary gland in infertile men with varicocele; 2) worsening in Leydig cells and tubular lesions with longer duration of varicocele; and 3) absence of any gross abnormality in hCG binding to its specific receptors in the testis of men with varicocele. These data suggest varicoceles may play a causal role in infertility.

LH/hCG receptors and stimulation of testosterone biosynthesis in the rat testis: changes during foetal development in vivo and in vitro

The development of gonadotropin receptors to LH/hCG in the foetal rat testis from 14 to 20 days of gestation was monitored by quantitative binding assays using [125I]hCG and compared to testosterone secretion under basal and stimulated conditions in vitro. Specific hCG binding was first detected on day 15. Thereafter the binding increased gradually with advancement in gestational age and correlated with LH-stimulated secretion of testosterone in vitro. On day 18 of gestation the KA was 0.82 x 10(10) M-1 and the binding capacity was 0.57 fmoles per testis. No binding was detectable in the female gonads at this age. The differentiation of hCG receptors obtained in vitro was very low, although it was sufficient to give a full response to LH with testosterone biosynthesis. The results of the present study suggest that functional receptors do not appear before the capacity to synthesize testosterone is expressed and that their appearance is not dependent on factors extrinsic to the testis. However, additional factors could be necessary for a full development of the receptors.

The effects of neuraminidase and gangliosides on ovarian LH/hCG receptors during rat development

Ovaries of neonatal rats are not endowed with specific LH/hCG receptors up to 6-8 days of age. Treatment of ovarian membranes of the neonatal rat with neuraminidase results in a specific binding of radioactively labeled hCG, while an increase of hormone binding is observed after neuraminidase treatment of ovarian membranes of the 21-day-old rat. These changes in hormone receptor sites in the ovary are dependent on the neuraminidase concentration used and are due to a receptor with a dissociation constant (KD) of about 10(-9) M. The KD of the receptor in the LH/hCG sensitive ovary without neuraminidase treatment is about 10(-10) M. These results indicate the presence of two different LH/hCG receptors in the ovarian membrane. The unmasking effect of neuraminidase onto LH/hCG receptors indicate that ganglioside-like structures are responsible for the masking of receptors in the neonatal, insensitive rat ovary and also in the 21-day-old sensitive ovary. Ganglioside preparations are able to inhibit the binding, and the fractionation of ovary gangliosides results in a fraction with a rather high inhibition potency of LH/hCG binding to the receptor. It is hypothesized that the masked receptor in the sensitive period represent a store of receptors for the reconstitution of the ovarian cells with active receptors after internalization of the hormone-receptor complex. Thus the masking of the receptors in the early postnatal rat ovary could be a prerequisite for the female differentiation of hypothalamic centers. The observed neuraminidase effect in vitro could reflect a physiologic situation. Neuraminidase was found in the ovary, and during early postnatal development the neuraminidase activity pattern coincides with that of the ovarian LH/hCG receptor changes.

Cyclic AMP phosphodiesterase in Leydig cell preparations of the rat testis

Enzymatic digestion of the interstitial tissue of early juvenile and adult rat testes resulted in an enrichment of the Leydig cell population. The cells of the intertubular preparation from adult testes were separated by centrifugal elutriation, according to differences in sedimentation velocity, a counter-flow centrifugation technique leading to 70% Leydig cell purity. Using this approach, it was possible to demonstrate that Leydig cells from adult testes contain only low affinity isoenzymes of cyclic AMP phosphodiesterase (PDE; E.C.: 3.1.4.17), an intracellular regulator of cAMP. Starch gel electrophoresis showed that the isozyme of cAMP PDe of Leydig cells is masked in crude testis homogenates due to the relatively low level of these cells in the total population. In Leydig cells, there are two different electrophoretic forms expressed which resemble two of eleven different molecular forms of cAMP PDE demonstrated for comparison in 21 different organs of the adult rat. An interstitial cell preparation from early juvenile testes, with a Leydig cell content of up to 20%, was also investigated electrophoretically with regard to molecular forms of cAMP PDE, the properties of which were characterized by kinetics analysis of cAMP hydrolysis. The results presented are discussed in relation to the onset of testosterone synthesis in Leydig cells of prepubertal rats leading to the initiation of male puberty.

LHRH and analogues as potential therapy for benign prostatic hyperplasia and hormone-dependent cancers

In adult male rats, daily s.c. injections of 0.008-125 microgram luteinizing hormone releasing hormone (LHRH) or its analogue (D-Ala, des-Gly-NH2)LHRH ethylamide, led to significant differences in inhibitory effects on testicular function and accessory sex organ weights. The analogue was at least 35 times more potent than LHRH in reducing testicular LH/hCG receptors and 350 times more effective in decreasing plasma testosterone concentrations. In a second study, adult male rats treated with 25-2500 microgram LHRH daily for a 3-week period showed 85%-90% decrease in plasma testosterone concentrations. Treatment with 25 or 250 microgram LHRH effected a maximal 25% and 40% decrease of the ventral prostate and seminal vesicles, respectively, without affecting the testicular weight, the latter being reduced by 15% with the higher dose of 2500 microgram. The LHRH analogue is proposed for the treatment of prostatic and breast cancers while native LHRH could be an effective therapy for benign prostatic hyperplasia.

Effect of oestrogen treatment on testicular LH/HCG receptors and endogenous steroids in prostatic cancer patients

LH/hCG binding and concentrations of pregnenolone, progesterone, 17-hydroxy-progesterone, androstenedione, testosterone and 5 alpha-dihydrotestosterone were measured in testicular tissue obtained from patients undergoing orchiectomy for prostatic cancer. One group of the orchiectomized patients had received an injection of 80 mg polyestradiol phosphate 1-9 days before the operation, another group were treated with monthly injections of the oestrogen for several months, and the remainder were not treated with oestrogen. In non-oestrogen treated patients (n = 8) the hCG-binding capacity was 28.0 +/- 15.0 (SD) ng/g and the equilibrium association constant of binding was 0.69 +/- 0.38 x 10(10) M-1. The binding capacity was significantly (P less than 0.025) lower (10.3 +/- 8.7 ng/g) in patients (n = 6) receiving the first oestrogen injection 3-9 days prior to the operation. A further decline to the level of 1.77 +/- 1.03 ng/g occurred in patients (n = 3) treated over 3 months with the oestrogen injections. At the same time, no significant changes were observed in peripheral serum LH and FSH levels. In the testicular endogenous steroid levels, statistically significant decreases were seen 9 days after the oestrogen injection in pregnenolone (from 505 +/- 315 ng/g to 138 +/- 86 ng/g) and in testosterone (from 669 +/- 243 ng/g to 254 +/- 49 ng/g) whereas no significant changes could be seen in the levels of the other steroids analysed. This study gives further evidence for the direct inhibitory action of oestrogens on human testicular steroidogenesis and suggests that the loss of testicular luteinizing hormone receptors may be one facet of this inhibitory action.

Acquisition of sensitivity to LH in relation to foetal development. Stimulation of cyclic AMP and testosterone production in the rat testis

The ability of LH to stimulate, in vitro, adenylate cylcase activity and testosterone secretion was studied in foetal rat testes after prelabelling with [14C]adenine. As little as 0.1 ng/ml LH produced significant synthesis of cyclic AMP and testosterone secretion. Increase of cyclic AMP production was observed as early as 1 min after addition of LH (100 ng/ml), preceding the rise in testosterone synthesis and secretion. FSH and prolactin were not effective. LH-stimulation of cyclic AMP and testosterone production appeared concomitantly in rat foetal testes on day 15 of gestation and reached a maximum on day 18. Immature testes (14 days) developed functional receptors when cultured in a medium devoid of hormone. The results of the present study suggest that cyclic AMP mediates the effect of LH on steroidogenesis in foetal testes and that the differentiation of functional receptors occurs at the same time as the capacity for testosterone synthesis.

Utricular configuration in hypospadias and intersex

To evaluate the incidence and significance of an enlarged prostatic utricle in hypospadiac patients without underlying intersex 44 patients with the meatus located in the perineum, penoscrotal junction or proximal two-thirds of the penis were evaluated with cystourethroscopy immediately before the operation. There was an abnormally enlarged utricle in 57 per cent of the perineal, 10 per cent of the penoscrotal and none of the penile hypospadias and intersex revealed a high incidence of enlarged utricle or the presence of a vagina masculinus. Utricular enlargement in itself doses not indicate intersexuality but careful cystoscopic examination of its vault needs to be undertaken, searching for a cervix. An enlarged utricle can be a manifestation of delayed mullerian duct regression or decreased androgenic stimulation of the urogenital sinus.

Presence in normal human testes of a chorionic-gonadotropin-like substance distinct from human luteinizing hormone

The high rate of human chorionic gonadotropin production by testicular tumors caused us to investigate the possibility that normal human testes contain small amounts of that substance. Extracts of human testes obtained at autopsy demonstrated parallel inhibition curves to the human chorionic gonadotropin standard in a radioimmunoassay specific for the hormone. The immunoreactive material was adsorbed onto concanavalin A, a reaction characteristic of glycoproteins, and was eluted within the chorionic gonadotropin range on Sephadex G-100 column chromatography. Solubilized receptor proteins for the hormone could not be identified in the extracts. The demonstration that the normal human testes contain a glycoprotein similar or identical to human chorionic gonadotropin suggests that the fetal genome responsible for production of the hormone during pregnancy is not completely suppressed in the adult. Excessive productton of this glycoprotein may account for the high levels of human chorionic gonadotropin reported in the serum of patients with germ-cell tumors of the testes.