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Biomedical subjects

A Steinberger

Publications and source records attributed to A Steinberger.

At least 55 records · Page 3Linked to original sources
PubMed1983

Interaction of progestins with Sertoli cell androgen receptors.

In an attempt to distinguish between possible androgen- and progestin-mediated mechanisms in the Sertoli cell, two steroids previously shown to have high affinity for both progesterone and androgen receptors (U13851, 17 alpha-ethynyl-17-hydroxy-7 alpha-methylestr-4-en-3-one and U6817, 17-hydroxy-19-nor-17 alpha-pregn-4-en-3-one) have been compared with respect to a number of parameters with two steroids having high affinity only for progesterone receptors (U49836, 17 beta-methoxyestr-4-en-3-one and U56902, 17-methoxy-17 alpha-pregn-4-3n-20-yn-3-one). U13851 and U6817 were the most potent competitors for cytosol [3H]-R1881 (17-beta-hydroxy-17-methylestra-4,9,11-triene-3-one) binding sites and nuclear accumulation of label. While U49836 and U56902 were considerably less effective as competitors against [3H]-R1881, they were more effective than U13851 and U6817 as competitors against [3H]-progesterone. Only U13851 and R1881 increased Sertoli cell nuclear RNA polymerase II activity. These data substantiate previous suggestions that progestin binding proteins distinct from androgen receptors may exist in Sertoli cells. Moreover, the data also suggest that progestins which stimulate RNA polymerase II activity do so via androgenic mechanisms.

Animals↗
PubMed1983

Metabolism of 3H-estradiol-17 beta by cultures of isolated rat Sertoli cells and the effect of FSH: presence of 16 alpha-hydroxylase.

The ability of Sertoli cells to metabolize 3H-estradiol-17 beta was investigated utilizing Sertoli cell cultures isolated from 18d rat testes. The Sertoli cells converted estradiol-17 beta to estriol as shown by recrystallization of estriol from samples containing cells and media but not from cell-free control media. The effect of FSH treatment on such metabolism was investigated and was shown to be similar to nontreated samples. This is the first demonstration that 16 alpha-hydroxylase is present in Sertoli cells and that this enzyme activity is not under the influence of FSH.

Animals↗
PubMed1983

The treatment of Meniere's disease by acupuncture.

34 patients suffering from Meniere's disease were treated by acupuncture. Prior to acupuncture most of them had been treated with various other medical means without satisfactory results. After acupuncture treatment their condition greatly improved. The classic symptoms of Meniere's disease are vertigo, tinnitus and deafness, but for all the treated patients vertigo was the most uncomfortable and distressing symptom. In all our cases vertigo stopped after a few acupuncture courses; but in our opinion it is more important to follow and control hearing threshold, since if it remains stable the other symptoms of Meniere's disease also do not persist. All our patients were regularly followed by careful audiometric studies several years after acupuncture treatment. In most cases hearing level had not greatly varied, so the other symptoms of Meniere's disease were not present in any large degree.

Acupuncture Therapy↗
PubMed1983

A homologous radioreceptor assay for rat follicle-stimulating hormone.

A homologous radioreceptor assay (RRA) for rat FSH (rFSH), which is both sensitive and easy to perform, is described. The receptor preparation is isolated from a 12,000 X G pellet of rat testes homogenate prepared with a high speed tissue grinder using Tris buffer. The sensitivity of the assay extends below 10 ng rFSH RP-1 (approximately 0.13 ng purified I-3 rat FSH), and the range of the assay spans 2 orders of magnitude. The specific binding of the [125I]rFSH tracer is 22-28% of the total tracer added. Such binding, which exceeds previously published values by 2- to 4-fold, allows the addition of relatively small amounts of total tracer radioactivity, which, in turn, contributes to a low nonspecific binding and highly reproducible values for replicates (coefficient of variation, approximately 3.0%). This represents the first homologous RRA for rFSH using testicular receptors. Likewise, the sensitivity and reproducibility exceed those of previous RRAs for rFSH.

Animals↗
PubMed1983

Biphasic effect of gonadotropin-releasing hormone and its agonist analog (HOE766) on in vitro testosterone production by purified rat Leydig cells.

GnRH and GnRH agonists have stimulatory and inhibitory effects on testicular testosterone secretion both in vivo and in vitro. To determine whether they are exerted directly on the Leydig cells and to explore the temporal relationships, we examined the effects of acute (3 h) and chronic (24-72 h) exposure of purified (greater than or equal to 80%) rat Leydig cells to GnRH and its agonist analog HOE766 (D-Ser-t-BU6,des-Gly-NH2 10LHRH ethylamide; Hoechst, Frankfurt, Germany) on testosterone production. GnRH and HOE766 enhanced basal testosterone secretion by freshly isolated or cultured Leydig cells. HOE766 was at least 100 times more potent than GnRH. However, exposure of Leydig cells to HOE766 for 24 h or longer lead to a significant reduction in hCG responsiveness without altering basal testosterone secretion. Both the stimulatory and inhibitory effects were dose related, with a maximal response elicited by 10(-9) M HOE766. HOE766 reduced Leydig cell sensitivity to hCG (ED50) stimulation, but did not alter the slope of the dose-response curves. Thus, GnRH and its agonist appear to have a dual and biphasic effect on the Leydig cells. Acute exposure stimulates basal testosterone secretion (and occasionally the hCG response), whereas chronic exposure decreases the response to hCG stimulation. These data provide additional evidence that GnRH has a direct effect on Leydig cell steroidogenesis.

Animals↗
PubMed1982

Specificity and nature of the rapid steroid-stimulated increase in Sertoli cell nuclear RNA polymerase activity.

This report explores the ability of various steroids to rapidly stimulate Sertoli cell RNA polymerase II activity and to compete with [3H]-androgens for nuclear and cytosol binding sites. Nuclear RNA polymerase II activity was significantly stimulated by a 1 nM concentration of the androgenic compounds testosterone, dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one). R1881 (methyltrienolone) and 5 alpha, 17 beta-diol and also by the potent progestins 6 alpha methylprogesterone and R5020 (17,21-dimethyl-19-nor-4-pregna-3,20-dione). Progesterone, 17 alpha-hydroxyprogesterone, estradiol, androsterone, and 5 alpha-androstan-3 beta, 17 beta-diol were ineffective at 1 nM. Cytosol binding and nuclear accumulation of [3H]-androgen was effectively reduced by 100 fold molar excess of those androgens and progestins which stimulated RNA polymerase II activity. These data suggest that androgens and progestins bind to at least some of the same proteins in the Sertoli cell and may elicit the rapid stimulation of RNA polymerase II activity via a common mechanism. Agarose gel electrophoresis of the nuclear RNA synthesized as a result of exposure to testosterone indicated that is was heterodisperse and in part polyadenylated. Electrophoresis of the poly A+-RNA demonstrated that testosterone administration increased the incorporation of [3H]-UTP into RNA that was larger than 28 S.

Androgens↗
PubMed1982

Effect of sodium molybdate on the binding of androgen-receptor complexes to germ cell and Sertoli cell chromatin.

This study explores the effect of molybdate on androgen receptors in relation to chromatin binding. Two fractions of testicular and prostatic cytosol were obtained by ammonium sulfate precipitation at 15-37% (I) and 37-47% (II) saturation. Both fractions from either tissue exhibited specific binding of [3H]-androgens which was thermolabile. With the exception of testicular fraction II, all fractions bound to Sertoli cell and germ cell chromatin. Prostatic [3H]-androgen-receptor complexes isolated from cytosols in the presence of 10 mM sodium molybdate showed a decreased ability (only 20-40%) to bind to either Sertoli cell or germ cell chromatin. Similarly, testicular [3H]-androgen-receptor complexes isolated in the presence of molybdate bound less well (60-70%) to Sertoli cell chromatin. On the other hand, inclusion of molybdate subsequent to ammonium sulfate precipitation did not significantly alter the binding ability of the receptor complexes to either chromatin. Also, the presence of molybdate during the receptor-chromatin interaction did not significantly decrease the ability of either prostatic or testicular androgen-receptor complexes to bind to Sertoli cell chromatin. These results indicate that the addition of molybdate prior to ammonium sulfate precipitation may impede the activation of androgen-receptor complexes by salt, resulting in a decreased ability of the steroid-receptor complexes to bind to chromatin acceptor sites. The data also indicate that molybdate exerts its inhibitory effect directly on the nonactivated receptor complexes and not on the chromatin acceptor sites.

Animals↗
PubMed1982

Kinetics of the double-antibody, liquid-phase radioimmunoassay for rat gonadotropins.

The liquid phase, double antibody radioimmunoassays for rat LH and FSH were studied with respect to the minimum duration required for their completion using NIAMDD (National Institute of Arthritis, Metabolism and Digestive Diseases) reagents at their recommended dilutions. The minimum assay duration, which still allows maximum sensitivity, at temperatures not exceeding room temperature is 3 days for the LH assay and 4 days for the FSH assay. The extra day for the FSH assay is due to apparently nonreversible binding of rat FSH to anti-rat FSH. Such nonequilibrium binding was also observed under certain conditions with the LH assay. The greatest tracer binding was observed at a I-Ab (rabbit anti-LH or anti-FSH) incubation of 1 day at 27 degrees C plus 1 day at 4 degrees C followed by 1 additional day at 4 degrees C with the II-Ab (antirabbit gamma-globulin).

Animals↗
PubMed1982

Testosterone metabolism by proximal and distal regions of the vas deferens from immature and mature rats.

The vas deferens, an androgen-dependent organ, may have physical importance in sperm maturation, yet very little is known about its steroid capabilities. To explore the steroid metabolic activities and their possible changes during sexual maturation, a comparative study of [14C]testosterone metabolism by the proximal (VDP) and distal (VDD) segments of the vas deferens from immature and mature rats was carried out in vitro. Approximately 50 mg of the VDP and VDD portions of the vas deferens, devoid of spermatozoa, were incubated in duplicates for 3 h at 37 degrees C with [14C]testosterone (53.5 microCi/mmol) and the essential cofactors. After the addition of appropriate 3H-labeled recovery tracers to the incubates, the steroids were extracted, separated by paper and thin-layer chromatography and crystallized to constant 3H/14C ratio in 3 consecutive crystals. The results showed that all tissues metabolized [14C]testosterone into 4 major steroids: dihydrotestosterone (DHT), 5 alpha-androstane-3 alpha-17 beta diol (5 alpha-3 alpha-diol), delta 4-androstenedione and androsterone. The metabolites accounted for approximately 16% and approximately 6% of the conversion products in the immature and mature vas deferens respectively. There was no significant difference in [14C]testosterone metabolism when VDP and VDD were compared within either age group of animals. However, the immature vas deferens was significantly more active compared to mature vas deferens in the synthesis of these metabolites, indicating that the activities of 5 alpha-reductase, 3 alpha-hydroxysteroid dehydrogenase and 17 beta-hydroxysteroid dehydrogenase diminish during sexual maturation. The possible physiological significance of these changes during maturation of the vas deferens is discussed.

Aging↗
PubMed1982

Characterization of Sertoli cell RNA synthetic activities in vitro at selected times during sexual maturation.

In this study, Sertoli cell RNA synthetic activity in vitro was characterized at selected times during sexual maturation. Sertoli cells, isolated from rat testes undergoing the first wave of spermatogenesis and placed in culture for 4 days, exhibited 2-fold increases in soluble ribonucleotide pools and in total RNA concentrations over the age span of 18-35 days. High performance liquid chromatographic analysis of the ribonucleotide pools in Sertoli cells cultured from 18- and 33- to 34-day-old rats revealed that, in addition to the overall age-related doubling of concentrations, uridine triphosphate (UTP) and cytidine triphosphate (CTP) pools were disproportionately increased 4- and 6-fold, respectively. In general, Sertoli cell contained relatively small amounts of UTP in comparison to several other cell types, but exhibited a high ADP:ATP ratio. A uniform 2-fold increase in the base composition of Sertoli cell RNA per mg DNA was observed over the age span of 18-35 days, with no preferential increase in any one specific nucleotide. There was no change in [3H]uridine incorporation (2 h) into RNA per cell (pmol/mg DNA), but decreased specific activity of the RNA (pmol/mg RNA) in Sertoli cells cultured from 35-day-old rats as compared to those from 18- to 19-day-old rats. Similar differences were noted in the specific activity of label incorporated into specific RNA bases. In contrast, the specific activity of the UTP-CTP soluble pool/mg DNA was only slightly increased. These data indicate that processes related to RNA synthesis in the Sertoli cell undergo a number of changes during the period of sexual maturation.

Animals↗
PubMed1982

Pituitary-testicular function in protein-deficient rats. Follicle-stimulating hormone hyperresponse to castration and supersensitivity of gonadotropin secretion to androgen negative feedback.

Previous studies have shown that weanling male rats fed a low protein diet ad libitum develop hypogonadotropic hypogonadism. Two unusual features of this state were 1) subnormal serum FSH in noncastrate rats but not in castrate rats, suggesting that FSH was being suppressed by a testicular factor, and 2) serum FSH increases after castration that were greater in protein-deficient rats than in controls. In the current study, protein-deficient rats showed FSH hyperresponse to castration, compared to either ad libitum or pair-fed controls, after periods of low protein feeding from 1-8 weeks and periods of castration from 1-8 weeks. FSH hyperresponse to castration was rapidly induced after the start of low protein feeding and was present whether castration was performed before or after low protein feeding was begun. In none of these circumstances did protein-deficient rats show LH hyperresponse to castration. Inhibin production of Sertoli cell cultures prepared from protein-deficient rats was less (P less than 0.02) than in ad libitum or pair-fed controls, suggesting that inhibin overproduction was not the cause of subnormal serum FSH in noncastrate protein-deficient rats. However, castrated rats fed a low protein diet were more sensitive to the negative feedback effects of testosterone on gonadotropin secretion than were ad libitum or pair-fed controls. We conclude that low serum gonadotropins in protein-deficient male rats may be related to hypersensitivity of these animals to the negative feedback effects of testosterone on gonadotropin secretion. In addition, FSH hyperresponse to castration, without corresponding LH hyperresponse, seems to be typical of protein deficiency, suggesting that protein deficiency may be a useful model for exploring the differential control of gonadotropin secretion.

Animals↗
PubMed1982

Binding of 3H-Sertoli cell factor to rat anterior pituitary in vitro.

The binding characteristics of Sertoli Cell Factor (SCF) to the anterior pituitaries were examined using tissue homogenates and cultured cells. Tritium-labeled SCF (3H-SCF), synthesized by rat Sertoli cells in vitro in the presence of 3H-leucine and partly purified by Sephadex gel chromatography, was used to the ligand. The binding of 3H-SCF to the pituitary homogenates or cultured cells was considerably greater (3-6X) compared to homogenates of brain, kidney, liver, spleen and testis. The pituitary binding at 37 C occurred after approximately 60 time dependent, and directly related to the receptor concentration. Maximum binding at 37 C occurred after approximately 60 min of incubation. Over 90% of the bound 3H-SCF was competitively inhibited by an excess of unlabeled SCF, but not by other substances. There was a good correlation between the binding of 3H-SCF and its biological activity, as evidenced by a selective suppression of basal FSH release in pituitary cell cultures. These data indicate that, in analogy to other protein hormones, specific binding to target cell receptors may represent an initial step of SCF action in the pituitary. The binding should also prove valuable in the development of a rapid radio-receptor assay for SCF and possibly for other inhibin preparations.

Animals↗
PubMed1981

Identification and characterization of a beta 1-adrenergic receptor in the rat Sertoli cell.

The beta 1-adrenergic receptor of rat Sertoli cells was characterized by measurement of the ability of adrenergic receptor agonists and antagonists to stimulate cAMP accumulation in Sertoli cells from 18-day-old rats. Epinephrine, norepinephrine and isoproterenol stimulate cAMP accumulation in Sertoli cells which is not additive with maximal doses of FSH and which is age-dependent, beta-antagonists, alprenolol, hydroxybenzylpindolol or propranolol inhibit isoproterenol-induced cAMP accumulation while alpha-adrenergic antagonists have no effect. Dobutamine and soterenol stimulated cAMP accumulation to a greater extent than albuterol and metoproterenol. Finally, the stimulatory effects of isoproterenol and zinterol are both more sensitive to inhibition by beta 1-antagonists than by beta 2-antagonists. Taken together these data indicate the presence of a beta 1-adrenergic receptor in Sertoli cells which is coupled to adenylate cyclase.

Adrenergic beta-Agonists↗
PubMed1981

The treatment of dysmenorrhea by acupuncture.

Forty-eight female patients suffering from dysmenorrhea in various degrees were treated by acupuncture. Seven standard acupuncture loci were selected. Acupuncture was given only 5 times to 44 of these patients. The results were analyzed after 6 to 12 months. Although the therapy was short, limited to only 7 points and uniform, satisfactory results were found in more than 80% of the cases.

Acupuncture Therapy↗
PubMed1981

Temporal and quantitative correlations between nuclear androgen binding and stimulation of rna polymerase II activity in Sertoli cells.

The nuclear accumulation of 3H-androgen had been correlated with the effects of this steroid on nuclear RNA polymerase activity in the Sertoli cell under identical experimental conditions. The synthetic androgen methyltrienolone (R1881) was chosen to avoid ambiguities caused by metabolism of the radioligand. Nuclear accumulation of specifically bound 3H-R1881 was apparent after 5 min and preceded RNA polymerase II activation. RNA polymerase II activity was significantly increased by 10 min after administration of R1881, and the response was maximal at 15 min. Although nuclear binding of 3H-R1881 continued to increase over this interval, the enzyme activity declined to basal levels by 20 min. Saturation of nuclear binding sites required concentrations of R1881 that were approximately one order of magnitude higher than those required for maximal polymerase II activation at 15 min. The results indicate that occupancy of only a small fraction of the specific nuclear binding sites by androgen is required to elicit maximal elevation of RNA polymerase II activity in cultured Sertoli cells.

Animals↗