Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The radioreceptor assay system for TSH is considered to be useful in quantitating the hormone and analyzing the mechanism of its action. The assay was established, and the interaction of abnormal thyroid stimulators in Graves' patients was evaluated in this assay system. A 10,000xg fraction of human thyroid homogenates was used as the receptor. Human TSH supplied from NIH was iodinated by using lactoperoxidase. The binding of 125I-TSH to the receptor was small, and 125I-TSH was further purified by the receptor binding. The receptor (25mg equivalent), purified 125I-TSH, and standard TSH or a sample were incubated at 37 degrees C for 60 min in a final volume of 300 microliters. The binding of 125I-TSH to the receptor was time- and temperature-dependent with optimal binding under the conditions described above. The binding was completely inhibited by the addition of human, bovine and ovine TSH and partially inhibited by high concentrations of HCG, FSH-LH. However, there was no cross reactivity with insulin, prostaglandin E1, E2, T3, T4 and Nal. The assay was sensitive enough to detect 5 to 50 microU of TSH. The amount of TSH bound to the receptor was almost parallel to the TSH concentration which is necessary to stimulate human thyroid adenylate cyclase activity. Studies of dissociation kinetics and Scatchard plot indicated that there were two classes of TSH receptors in the human thyroid. A higher association constant was calculated as 1.5 x 10(8)M-1. LATS-IgG from a patient with Graves' disease completely inhibited the binding of 125I-TSH to the receptor, and studies of Lineweaver-Burk, plot suggested that TSH and LATS-IgG shared common binding sites. The radioreceptor assay of TSH appears to be useful in evaluating the abnormal thyroid stimulators present in Graves' disease.
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PMID:[Studies on the radioreceptor assay of TSH: the binding of 125I-TSH to the human thyroid receptor and the interaction of LATS-IgG (author's transl)]. 22 97

The interaction between gonadotropin and prolactin (PRL) on ovarian steroidogenesis as well as c-AMP production was studied in rat ovaries. Ovaries obtained from adult female Wistar rats in a morning of proestrus were chopped into 30-40 pieces and subjected to short term incubation studies using various buffers. HCG-stimulated c-AMP, estradiol (E2), progesterone (P) secretions were suppressed in a dose-dependent manner by ovine (o) PRL in a plain Gey-Gey (G-G) buffer. Addition of 3-isobutyl-1-methyl-xanthine (IBMX) increased c-AMP accumulation as well as E2 and P secretions. Deletion of Ca++ from the IBMX buffer stimulated c-AMP production, but suppressed steroid secretion. The inhibitory effect of PRL on E2 and P was not demonstrated in IBMX buffer at any Ca++ concentration examined despite suppression of c-AMP production. In conclusion, it was demonstrated that PRL inhibited gonadotropin-stimulated production of E2 and P by inhibiting c-AMP production. IBMX stimulated accumulation of c-AMP, E2 and P and counteracted with the antigonadal effect of PRL. Ca++ inhibited c-AMP accumulation but stimulated E2 and P secretions. The data suggested that PRL exerts its antigonadal effect through an inhibition of adenylate cyclase action in a manner similar to that of Ca++.
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PMID:Prolactin interacts with gonadotropin through a suppression of c-AMP production probably as a LH-sensitive adenylate cyclase inhibitor. 242 48

To evaluate the direct inhibitory action of luteinizing hormone-releasing hormone (LH-RH) on the steroidogenesis of the human ovary, the primary cultured human corpus luteum cells were investigated. The following were the effects of the addition of LH-RH: Estradiol (E2) and progesterone were produced and secreted in the cultured corpus luteum cells. In the cytoplasm of the cultured corpus luteum cells, E2 and P-antibody complexes were observed as fine granules by the immunohistochemical staining method. The progesterone production of these cells was not inhibited in the cells cultured with LH-RH 10(-8) Mol alone. The progesterone production of the cells was stimulated in the cells, cultured with gonadotropins (LH, HCG and HMG). The gonadotropin stimulated progesterone production was inhibited by LH-RH administration in the cells. In the short term incubation of the human corpus luteum cell suspension, the cyclic adenosine monophosphate (c-AMP) accumulation of the cells incubated with LH-RH alone did not change, but the gonadotropin-stimulated c-AMP accumulation of the corpus luteum cells was significantly inhibited by LH-RH. Concerning these results, it is concluded that LH-RH inhibits the gonadotropin stimulated progesterone production directly in vitro. It is suggested that the mechanisms of these inhibitory actions of the LH-RH are related to the gonadotropin receptor-adenyl cyclase systems, c-AMP metabolizing enzyme and/or progesterone metabolizing enzyme.
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PMID:[Study on the direct inhibitory action of luteinizing hormone-releasing hormone on the steroidogenesis of cultured human corpus luteum cells]. 300 Nov 99

Human granulosa cells were isolated from preovulatory follicles during cycles stimulated with HMG-HCG or clomiphene-HMG-HCG or from unstimulated cycles. The cells were cultured for 6-8 days in medium M199 containing fetal calf serum under 5% CO2 in air. Highly purified human prolactin and human chorionic gonadotrophin were added alone or in combination to the cultures, and the content of steroids in the medium was measured every second day, utilizing conventional RIA techniques. In the presence of HCG the formation of progesterone (P) increased 3-5-fold over the control level with maximal effect after 4 days. In cells derived from clomiphene-HMG-HCG stimulated cycles, prolactin per se did not influence basal P formation but reduced the stimulatory effect of HCG. This was only seen in granulosa cells from follicles greater than 20 mm in diameter. In experiments with Forskolin, an adenylate cyclase activator, P formation was stimulated and the stimulation was counteracted by the concomitant presence of prolactin, indicating that prolactin did not interfere with the LH-HCG receptor. In cells from smaller follicles, or in cells from follicles aspirated from the natural cycle prior to the endogenous LH peak, P formation was stimulated by HCG but the addition of prolactin did not reduce this stimulatory effect. The results are discussed in relation to earlier reports on prolactin effects in vitro both on laboratory animals and human material.
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PMID:Prolactin and gonadotrophin interactions on progesterone formation in cultured human granulosa cells. 313 1

Previous studies have shown that anti-idiotypic antibodies can be developed in vivo through animal immunization with idiotype, and that these antibodies can be isolated from other anti-immunoglobulin antibodies by affinity purification. These techniques have relied on large amounts of idiotype, which were produced either by hyperimmunization or by monoclonal antibodies, to serve as the affinity adsorbent. In the present study, we produced anti-idiotypic antibodies to human anti-thyroid-stimulating hormone (TSH) receptor antibodies by first injecting rabbits with (TSH receptor purified) IgG from Graves' patients. The resulting antiserum was then adsorbed with Sepharose-coupled TSH in an attempt to specifically bind and isolate the anti-idiotype. The antibody obtained from this process was shown to bind specifically to TSH receptor-binding antibodies from Graves' patients, and this binding could be inhibited by 56% with the addition of 10(-4) M TSH but not by HCG (10(-2) M). The anti-idiotype also bound to TSH, and this binding could be specifically inhibited by receptor-purified Graves' IgG (60% inhibition at 10 micrograms/ml IgG), but not by IgG from normal subjects (no inhibition at 50 micrograms/ml IgG). In a TSH receptor binding assay, the anti-idiotype could inhibit TSH receptor binding in Graves' sera at a 1,000-fold lower concentration than could anti-kappa/lambda antiserum; the anti-idiotypic antiserum also inhibited in vitro TSH-mediated adenylate cyclase stimulation at an IgG concentration of 5 micrograms/ml, while heterologous anti-TSH antisera and normal IgG at similar concentrations had no effect. Finally, despite being generated against a single patient's TSH receptor binding antibody, the anti-idiotype was able to block TSH receptor binding in the serum of six other Graves' patients, thus suggesting that there may be conformational conservation in the antigen that is recognized by different individuals' TSH receptor-binding immunoglobulins.
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PMID:Production, isolation, and characterization of rabbit anti-idiotypic antibodies directed against human antithyrotrophin receptor antibodies. 608 14

The ultrastructural localization and the activity changes of adenylate cyclase (AC) were studied in the ovarian compartments of sexually mature ground squirrels (Citellus citellus L.), during the both stages of hibernation (October to December and January to February), after awakening (March) and after gonadotropin (PMSG and HCG) intraperitoneal application during the both above mentioned stages. AC activity was found to be localized on the plasma membranes of theca interna, interstitial, and granulosa cells in ground squirrel ovary. The cytochemical observations presented demonstrate significant AC activity changes in ground squirrel ovary during hibernation, after awakening gonadotrophin treatment and lend support to the concept of AC-cAMP system participation in the gonadotrophin hormone action on the ovary.
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PMID:Electron microscopic cytochemistry of adenylate cyclase in the ovarian compartments of ground squirrel during the annual cycle. 680 84

The dose and temporal (1-24 h) effects of two phenothiazines, chlorpromazine and trifluoperazine, on steroidogenesis and adenylate cyclase activity of gonadotropin-responsive Leydig tumor cells (M5480A) in primary culture were examined. At low doses (e.g. 0.1-1 microM) these antipsychotic drugs were slightly inhibitory (trifluoperazine) or without effect (chlorpromazine), while at 25 microM each drug was weakly stimulatory to basal testosterone production. Trifluoperazine was, in general, inhibitory to HCG-stimulated testosterone production, but chlorpromazine exhibited paradoxical effects. At 5 and 10 microM this neuroleptic agent increased HCG-stimulated steroidogenesis, while at 25 microM testosterone production was inhibited. In a particulate fraction prepared from the tumor the activity of adenylate cyclase was stimulated 3.4-fold in the presence of 10 microM 5'-guanylimidodiphosphate and 5-fold in the presence of HCG plus the non-hydrolyzable GTP analogue. Between doses of 1-100 microM neither drug altered the basal activity of adenylate cyclase. Trifluoperazine at doses of 1-100 microM inhibited 5'-guanylimidodiphosphate-stimulated adenylate cyclase activity both with and without added gonadotropin. At doses of 1-10 microM chlorpromazine had no effect on adenylate cyclase activity, but it stimulated activity in the dose range of 20-100 microM. Interestingly, in the presence of 5'-guanylimidodiphosphate this drug did not alter the stimulated enzymic activity achieved with a maximal dose of HCG. Therefore, these phenothiazines exhibit quite divergent dose-dependent effects and their actions must occur at multiple loci. Also, it seems unlikely that the effects of these agents on steroidogenesis and adenylate cyclase activity can be reconciled solely in terms of calmodulin-mediated processes.
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PMID:Divergent effects of phenothiazines on Leydig tumor cell steroidogenesis and adenylate cyclase activity. 688 21

Oxidized(OX)-low density lipoprotein (LDL) inhibits steroidogenesis by luteal cells (LC) from regressing porcine CL. The present study was designed to investigate the mechanism of inhibition by determining whether OX-LDL inhibits basal and agonist-stimulated cAMP production in regressing LC. Collagenase-dispersed porcine LC (n = 7 animals, estrous cycle Day 12-15) were cultured (2.5 x 10(5) cells/0.5 ml) in serum-free DMEM/Hams F-12 in duplicate wells at 37 degrees C. Approximately 18 hr after plating, media were replaced and LC were immediately treated with human LDL (0, 25, or 100 microg/ml) or OX-LDL (25 or 100 microg/ml). LC were incubated for 2 hr before addition of isobutylmethylxanthine (IBMX) to inhibit phosphodiesterase activity, immediately followed by hCG (100 ng/ml), cholera toxin (CT; 0.1 microM), forskolin (FS; 50 microM), or no further treatment (controls). LC were incubated for an additional 90 min. After removal of culture media, cells were extracted with 0.1 N HCl. Cell extracts were assayed for cAMP by enzyme immunoassay (EIA). HCG, CT, and FS increased (P < 0.05) cAMP production approximately four-, 10-, and 25-fold, respectively, relative to controls. OX-LDL (25 and 100 microg/ml) inhibited (P < 0.05) cAMP production by unstimulated, hCG-, and CT-stimulated LC, but not that by FS-stimulated LC. The highest concentration of OX-LDL (100 microg/ml) reduced cAMP formation by 39.8 +/- 6.6%, 44.7 +/- 10.5%, and 67.7 +/- 4.5% in unstimulated, hCG-, and CT-stimulated LC, respectively. In contrast, unmodified LDL (25 and 100 microg/ml) did not alter cAMP production. We conclude that OX-LDL can interfere with the cAMP signaling pathway in regressing luteal cells by acting at sites proximal to adenylate cyclase activation.
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PMID:Oxidized-low density lipoprotein inhibits cyclic AMP production by porcine luteal cells. 1070 69