Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The actions of vasoactive intestinal peptide (VIP) on intracellular cyclic AMP, in primary cultures of striatal neurons, were examined. VIP stimulated cyclic AMP formation five-fold over basal levels in neurons after 6 days in vitro (DIV); half maximal activation (EC50) was obtained with 10 nM of the peptide. VIP stimulation was both more potent and effective than those due to adrenocorticotropin (ACTH), dopamine (DA) or serotonin (5-HT). VIP efficacy was augmented to 15-20-fold in the presence of 0.1 microM forskolin, which had virtually no effect on cyclic AMP production alone; VIP potency was unaffected. At saturating concentrations of VIP (0.1-1.0 microM), no other agonist can further activate cyclic AMP production. Under these conditions, the interaction with opiate, DA D2 and 5-HT1 receptors, whose activation results in the inhibition of cyclic AMP production, was shown. During the differentiation of striatal neurons, VIP stimulation of cyclic AMP over basal levels, in the presence of 0.1 microM forskolin, decreases progressively from 30-fold after 3 DIV to 11-fold after 10-13 DIV.
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PMID:Vasoactive intestinal peptide actions on cyclic AMP levels in cultured striatal neurons. 301 97

Immunoreactivity for endocrine peptides (serotonin, gastrin, somatostatin, insulin, corticotropin, calcitonin, neurotensin, vasoactive intestinal peptide, and bombesin), cytoskeletal proteins (high and low molecular weight keratins), and tumor differentiation markers (chromogranin, neuron-specific enolase, carcinoembryonic antigen, S100 protein, and Grimelius stain) was sought on nine cervical and one vaginal poorly differentiated small-cell carcinoids. Dense-core secretory granules were ultrastructurally identified in all cases (seven of ten) in which tissue was available for electron microscopy. Immunoreactivity for endocrine secretory products was rarely noted, and only in a minority cell population (serotonin in two of ten). The majority of the tumors exhibited immunoreactivity for low molecular weight keratin (AE1/AE3 in eight of ten; CAM 5.2 in seven of nine), and three of ten tumors focally expressed high molecular weight keratin. Among the markers of neuroendocrine differentiation, neurospecific enolase was more frequently expressed (ten of ten) than chromogranin (five of ten) or argyrophilia (three of ten). Carcinoembryonic antigen was present in eight of ten tumors. S100 protein was absent in all cases. In summary, poorly differentiated small-cell carcinoids of the lower female genital tract, similarly to other small-cell endocrine tumors, occasionally exhibit focal glandular and squamoid differentiation, and only relatively infrequently or focally express immunohistochemically detectable endocrine secretory products, chromogranin, and argyrophilia.
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PMID:Endocrine and tumor differentiation markers in poorly differentiated small-cell carcinoids of the cervix and vagina. 302 70

In this study a synthetic analog of the calmodulin-binding domain of myosin light chain kinase, a 17-amino-acid peptide (M5) was used to examine the possible role of calmodulin in melanotropin receptor function. Binding of beta-melanocyte-stimulating hormone to its membrane receptor and subsequent stimulation of adenylate cyclase (AC) were found to be specifically inhibited by M5 in a dose-dependent and noncompetitive manner, both in intact M2R melanoma cells and in a plasma membrane preparation derived thereof. Half-maximal inhibition of both hormone binding and melanotropin-sensitive AC activity was shown to occur at approximately 1 microM M5. In contrast, stimulation of AC by prostaglandin E1, guanosine 5'-O-(3-thio)triphosphate, forskolin, and unstimulated enzyme activity were unaffected by the presence of M5, under the same assay conditions. Furthermore, addition of a molar excess of calmodulin to the AC assay completely abolished the inhibitory effects of the peptide on melanotropin-stimulated AC activity. Other peptides of similar size, which bind to calmodulin with low affinity (e.g. glucagon, somatostatin, and vasoactive intestinal peptide), were shown to be totally ineffective in inhibiting melanotropin-sensitive AC. These findings, along with those shown previously for other antagonists of calmodulin, suggest a role for an M5-binding protein, as of yet unidentified, involved in the regulation of the melanotropin receptor function.
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PMID:A synthetic analog of the calmodulin-binding domain of myosin light chain kinase inhibits melanotropin receptor function and activation of adenylate cyclase. 336 68

In this study, two melanotropin binding proteins from M2R melanoma cells have been identified based on the photochemical cross-linking of [125I]iodinated porcine beta-MSH ([ 125I]iodo-beta-MSH) to melanoma cell membranes, using N-hydroxysuccinimidyl-azidobenzoate. Autoradiography of photoaffinity-labeled M2R membrane protein, after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed the specific labeling of two separate bands with an apparent molecular mass of 43 and 46 kilodaltons, respectively. Photoaffinity labeling of both bands was of near-equal intensity and could be inhibited, in a dose-dependent manner, by the addition of unlabeled beta-MSH before photolysis. In addition, agents known to inhibit the binding of beta-MSH to its cellular receptor, such as EGTA, GTP, guanosine 5'-O-(3-thio)triphosphate, and a synthetic analog of the calmodulin-binding domain of myosin light chain kinase-M5, were all found to specifically inhibit the labeling of these two protein bands by the azido derivative of [125I]iodo-beta-MSH. In contrast, addition of a nonrelated peptide, vasoactive intestinal peptide, had no effect upon the labeling of these melanotropin-binding proteins. On the basis of these results we suggest that the two proteins may function as the binding domain(s) of the cellular receptor for melanotropins, or may represent entire receptor moieties themselves.
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PMID:Identification and characterization of melanotropin binding proteins from M2R melanoma cells by covalent photoaffinity labeling. 341 15

We report a case of mammary intracystic papillary carcinoma occurring in a 75-year-old man. The tumor was present on the left pectoral area for five years. Grossly, the neoplasm was a cystic structure 10 cm in diameter, with multiple intramural filiform papillae and small foci of cyst wall invasion. By transmission electron microscopy the tumor cells had the normal complement of organelles and also multiple electron-dense, membrane-bound secretory granules. These granules were also demonstrated with multiple stains for argyrophilia and with periodic acid-Schiff. Immunoperoxidase stains were negative for neuron-specific enolase, S100 protein, vasoactive intestinal peptide, corticotropin, calcitonin, lactalbumin, and bombesin, and positive for human heart factor (myoepithelial cells) and carcinoembryonic antigen. We believe that this rare neoplasm represents a variant of mammary adenocarcinoma and not a neuroendocrine (carcinoid) neoplasm.
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PMID:Intracystic papillary carcinoma of the male breast. Immunohistochemical and ultrastructural study. 389 93

Centrally administered neuropeptides were investigated for their effects on the development of gastric lesions in rats. Thyrotropin releasing hormone (TRH), vasoactive intestinal peptide (VIP) and gonadotropin releasing hormone (LHRH) produced gastric lesions acutely, with TRH demonstrating the most pronounced effect in terms of incidence and severity. Ten-fold higher doses of the same peptides administered intravenously produced none or very few gastric lesions. Moreover, pretreatment with atropine partially inhibited their production. Corticotropin releasing factor (CRF) exhibited only mild ulcerogenic effects, and the gastric lesions induced with this peptide developed more slowly than with TRH, VIP and LHRH. Although ulcerogenic in their own right, none of these four neuropeptides significantly potentiated the potent ulcerogenic effects of cold-restraint stress. Since other neuropeptides, including somatostatin, human pancreatic growth hormone releasing factor (hpGRF), substance P, bombesin, and neurotensin, had no demonstrable effects on gastric mucosa, we can conclude that the lesions were not a general effect of intracisternal administration of neuropeptides. The results suggest that within the central nervous system, there are several neuropeptides that play a significant role in the development of gastric lesions via, at least in part, vagal-dependent mechanisms.
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PMID:The effects of centrally administered neuropeptides on the development of gastric lesions in the rat. 392 Apr 62

This paper deals with the cytological substratum for interactions between serotonin and dopamine, pro-opiomelanocortin (POMC) or vasoactive intestinal peptide (VIP) within the hypothalamus. Using a combination of radioautography and immunocytochemistry on the same thin sections in the rat, direct appositions not involving synaptic specializations were demonstrated between serotoninergic terminals and dopaminergic as well as POMC neurons in the arcuate nucleus. In the suprachiasmatic nucleus, quantitative data have indicated that VIP neurons constitute a preferential synaptic target for serotoninergic afferents. The functional implications of these results are discussed.
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PMID:[Ultrastructural relations between monoaminergic and peptidergic systems in the hypothalamus. Radioautographic approach and immunocytochemical binding in the arcuate nucleus and suprachiasmatic nucleus in the rat]. 408 12

Two cell culture systems were used for studies of neural functions in vitro. A neuronal hybrid cell line (neuroblastoma x glioma hybrid cells) and primary glial-rich cultures of newborn murine brain. The level of cyclic AMP in both systems is regulated by two groups of hormones, those that stimulate and those that inhibit formation of cyclic AMP. Among the inhibitory hormones active on the hybrid cells are opioids. Therefore the cells are being used in the elucidation of action of opioids. The list of stimulating and inhibitory hormones regulating the primary glial-rich cultures includes several peptide hormones such as the gastrointestinal peptides secretin and vasoactive intestinal peptide, the calcaemic hormones parathyrin and calcitonin, adrenocorticotropin and melanotropins, and somatostatin. Noradrenaline (via alpha- and beta-adrenergic receptors) and adenosine (via A1 and A2 receptors) inhibit and stimulate cyclic AMP synthesis in the primary glial-rich cultures. Bradykinin slowly hyperpolarizes the hybrid cells and elicits formation of cyclic GMP. Both responses desensitize rapidly. Substance P increases the permeability of hybrid cells for Na+, as measured by using 14C-guanidinium as substitute for Na+. Hybrid cells actively accumulate taurine, an amino acid that appears to fulfill important functions in the nervous system. The transport of taurine across the plasma membrane is highly specific for and strictly dependent on Na+. The pumped station hypothesis of taurine action in the nervous system views taurine gradient plus taurine carrier as a transport system for the elimination of sodium from neurons during phases of high neuronal activity.
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PMID:Cell culture as models for studying neural functions. 608 74

[125I]Iodo-Tyr1-somatostatin (SRIF) binds with high affinity to one class of sites in the rat anterior pituitary with a KD of 0.91 +/- 0.22 nM and a receptor concentration of 104.4 +/- 1.9 fmol/mg protein. This binding is saturable with respect to tissue concentration and is time-, temperature-, pH-, and calcium-dependent. It is also reversible as a function of time. The rates of association and dissociation were calculated to be 5.98 X 10(7) M-1 min-1 and 0.578 min-1, respectively. Binding of [125I]iodo-Tyr1-SRIF is not inhibited by morphine, beta-endorphin, [D-Ala2]Met-enkephalin, LHRH, TRH, histidylproline diketopiperazine, neurotensin, substance P, bombesin or vasoactive intestinal peptide. In contrast SRIF, [Tyr1]SRIF, and [D-Trp8,D-Cys14]SRIF displace [125I]iodo-Tyr1-SRIF binding with Ki values 0.10 +/- 0.05, 0.46 +/- 0.18, 0.05 +/- 0.01 nM, respectively. The constants of inhibition of a series of alanine monosubstituted analogs of SRIF are correlated (r = 0.89) with their biological potency on GH secretion. Furthermore, postnatal development patterns of [125I]iodo-Tyr1-SRIF binding sites follow the ability of SRIF to inhibit GH release. Thus, [125I]iodo-Tyr1-SRIF binding to adenohypophyseal membranes seems to reflect interaction with SRIF receptors on adenohypophyseal cells. Since biological effects of the peptide have been reported on GH, thyrotropin-stimulating hormone, and PRL secretion, further studies are required to determine the cell types upon which this binding occurs.
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PMID:Somatostatin receptors on rat anterior pituitary membranes. 612 57

The AtT-20/D16-16 mouse pituitary tumor cell secretes corticotropin (ACTH) in response to corticotropin-releasing factor (CRF), (-)-isoproterenol, and vasoactive intestinal peptide (VIP). These responses are associated with a rapid increase in cyclic AMP formation. Somatostatin (SRIF) markedly decreases the stimulatory effect of CRF, (-)-isoproterenol, and VIP on both cyclic AMP formation and immunoreactive ACTH secretion. Forskolin and cholera toxin, adenylate cyclase activators, also stimulate cyclic AMP formation and ACTH secretion in AtT-20 cells and these responses are all inhibited by SRIF. The ACTH secretory responses to melittin and to the calcium ionophore A23187, neither of which increases cyclic AMP in AtT-20 cells, were not inhibited by SRIF. SRIF did not affect the binding of a tritiated beta-adrenergic receptor antagonist to AtT-20 membranes nor did it decrease basal cyclic AMP formation even in the presence of excess phosphodiesterase inhibitor, indicating that the reduction of cyclic AMP levels by SRIF did not involve either an interference with beta-adrenergic agonist binding to receptors or stimulation of cyclic AMP degradation. These results indicate that the inhibition of CRF-, (-)-isoproterenol-, and VIP-stimulated ACTH secretion by SRIF may be regulated by its inhibitory action on adenylate cyclase.
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PMID:Somatostatin inhibits multireceptor stimulation of cyclic AMP formation and corticotropin secretion in mouse pituitary tumor cells. 612 32


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