Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cranial radiation for childhood cancer can cause growth hormone deficiency (GHD), usually due to hypothalamic rather than pituitary dysfunction. To investigate whether this hypothalamic dysfunction is secondary to altered neurotransmitter input from other brain centers, we used neurotransmitter-excitatory substances to study the GH secretory response in 17 children who had received 12 to 60 Grey (Gy) to the cranium and 40 short children with normal endocrine function. As expected, the irradiated children had decreased mean GH secretion in response to insulin-induced hypoglycemia and arginine infusion, and decreased mean 24 hour GH concentrations, compared to the control group. In contrast, the two groups had similar GH secretory responses to GHRH stimulation and somatostatin suppression. Assessment of neurotransmitter pathways in the irradiated children revealed significantly lower mean peak GH concentrations in response to 5 of the 6 substances tested compared to control children: alpha-adrenergic stimulation (clonidine), beta-adrenergic blockade (propranolol), cholinergic stimulation, dopaminergic stimulation (L-dopa), and GABA-ergic stimulation (valproic acid). Results of serotonergic stimulation (L-tryptophan) were not statistically significant. Eleven patients who had abnormal GH secretion underwent 4 or more tests with neurotransmitter-stimulatory agents; 3 patients had peak GH concentrations of < 2.5 micrograms/l to all tests, whereas 4 patients had a peak GH concentration of > or = 7 micrograms/l to one or more tests but < 5 micrograms/l to one or more other tests. These observations suggest that radiation damage may sometimes spare growth hormone-releasing hormone (GHRH) and somatostatin secretion while affecting neurotransmitter pathways. We postulate that the hierarchy of sensitivity to radiation damage may be hypothalamic and extra-hypothalamic neurotransmitters > hypothalamic GHRH and/or somatostatin secretion > pituitary GH secretion.
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PMID:Neurotransmitter control of growth hormone secretion in children after cranial radiation therapy. 810 3

To determine the component(s) of dietary protein that regulates GH-releasing factor (GRF) synthesis, we measured hypothalamic prepro-GRF mRNA by solution hybridization/nuclease protection analysis in food-deprived rats refed protein-free diets (PF) supplemented with individual amino acids. Adult male Sprague-Dawley rats were allowed free access to food (Fed), food deprived for 72 h (FD), or FD then refed for 72 h with a normal (NF) diet, a protein-free (PF) diet, or PF diets containing tyrosine, tryptophan (Trp), glutamic acid, or histidine (His). Food-deprived rats displayed the expected 80% reduction in hypothalamic prepro-GRF mRNA. Upon refeeding, levels were normalized in rats refed a normal diet, but not in those refed a PF diet alone or with tyrosine, Trp, or glutamic acid. In contrast, prepro-GRF mRNA was restored to 70% of Fed values by a PF diet with His. Supplementing a PF diet with His was sufficient to maintain hypothalamic prepro-GRF mRNA expression, as 3 days of feeding replete rats with PF diet or PF diet with added Trp resulted in a 50% reduction in prepro-GRF mRNA, whereas levels were reduced 25% by feeding animals a PF diet with His. Groups of rats allowed free access to food were treated for 72 h with two daily injections of 100 mg/kg alpha-fluoremethylhistidine, a specific irreversible inhibitor of histidine decarboxylase, to determine if the effect of His on prepro-GRF mRNA depended on neural conversion to histamine. alpha-Fluoremethylhistidine-treated rats showed a 40% reduction in hypothalamic prepro-GRF mRNA, with no concomitant change in preproneuropeptide-Y or preprosomatostatin. These data indicate that decreased hypothalamic prepro-GRF mRNA in FD rats is due in part to the lack of dietary and provide clear evidence for a role of the histaminergic neural system in the regulation of hypothalamic GRF expression.
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PMID:Regulation of hypothalamic preprogrowth hormone-releasing factor messenger ribonucleic acid expression in food-deprived rats: a role for histaminergic neurotransmission. 810 51

The studies were performed on cultured TT cells originating from human thyroid medullary carcinoma (i.e., from parafollicular cells of the thyroid). The amount of released calcitonin was dependent upon calcium level in the medium. Moreover, calcitonin secretion might be regulated by medium supplementation with polypeptide hormones. Somatostatin inhibited while glucagon and pentagastrin stimulated calcitonin secretion to t he medium. Calcitonin secretion was also influenced by biogenic amines and their precursors. Dihydroxy-1-phenylalanine and serotonin augmented while 5-hydroxy-1-tryptophan and dopamine inhibited calcium secretion. This, calcitonin secretion may be controlled by different substances present in the healthy organism. This points to a complex control of calcium ion level in the blood.
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PMID:Regulation of calcitonin secretion by thyroid parafollicular cells in vitro. 861 73

S-4-methoxytrityl cysteine was synthesized and converted into the corresponding Fmoc-Cys(Mmt)-OH by its reaction with Fmoc-OSu. As compared to the corresponding Fmoc-Cys(Trt)-OH, the S-Mmt-function was found to be considerably more acid labile. Quantitative S-Mmt-removal occurs selectively in the presence of groups of the tert butyl type and S-Trt by treatment with 0.5-1.0% TFA. The new derivative was successfully utilized in the SPPS of Tyr1-somatostatin on 2-chlorotrityl resin. In this synthesis groups of the Trt-type were exclusively used for amino acid side-chain protection. Quantitative cleavage from the resin and complete deprotection was performed by treatment with 3% TFA in DCM-TES (95:5) for 30 min at RT. We observed no reduction of tryptophan under these conditions.
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PMID:Synthesis of the very acid-sensitive Fmoc-Cys(Mmt)-OH and its application in solid-phase peptide synthesis. 874 Sep 63

Hormonal overproduction is a significant problem in patients with disseminated midgut carcinoid tumors. Serotonin (5-HT) is one major product secreted from such tumors and the urinary excretion of its metabolite (5-hydroxyindoleacetic acid, 5-HIAA) serves as an important tumor marker. The present study aimed at elucidating mechanisms of tryptophan metabolite secretion to facilitate the treatment of the carcinoid syndrome. When midgut carcinoid tumors were studied in primary cell cultures, several similarities with adrenergic neurons could be demonstrated. A marked dose-dependent depletion of intracellular 5-HT could be induced by reserpine, and monoamine oxidase-activity was revealed both in functional studies and by immunocytochemistry. Differences between tumors in the ratios of tryptophan metabolites released indicated that enzymes for synthesis and degradation of 5-HT were individually expressed. Treatment with the somatostatin analogue octreotide or with dexamethasone decreased the extracellular levels of tryptophan metabolites, but the mechanisms were partly different. In some tumors octreotide also decreased the synthesis of 5-HT, while dexamethasone markedly increased the intracellular 5-HIAA levels. It is of clinical interest to further elucidate these mechanisms, since the two drugs may have complementary actions in carotid crisis reactions.
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PMID:Secretory patterns of tryptophan metabolites in midgut carcinoid tumor cells. 923 53

The symptomatology of the fibromyalgia syndrome (FMS) often resembles an alteration in central nervous set points at least in three systems. The patients suffer under chronic pain in the region of the locomotor system, presumably reflecting a disturbed central processing of pain. Anxiety and depression often characterizes the clinical picture. Almost all of the hormonal feedback mechanisms controlled by the hypothalamus are altered. Characteristic for FMS patients are the elevated basal values of ACTH, follicle-stimulating hormone (FSH), and cortisol as well as lowered basal values of insulin-like growth factor 1 (IGF-1, somatomedin C), free triiodothyronine (FT3), and oestrogen. In FMS patients, the systemic administration of the relevant releasing hormones of corticotropin-releasing hormone (CRH), growth hormone-releasing hormone (GHRH), thyreotropin-releasing hormone (TRH), and luteinizing hormone-releasing hormone (LHRH) leads to increased secretion of ACTH and prolactin, whereas the degree to which TSH can be stimulated is reduced. The stimulation of the hypophysis with LHRH in female FMS patients during their follicular phase results in a significantly reduced LH response. All in all, the typical alterations in set points of hormonal regulation that are typical for FMS patients can be explained as a primary stress activation of hypothalamic CRH neurons caused by the chronic pain. In addition to the stimulation of pituitary ACTH secretion, CRH activates somatostatin on the hypothalamic level, which in turn inhibits the release of GH and TSH on the hypophyseal level. The lowered oestrogen levels could be accounted for both via an inhibitory effect of the CRH on the hypothalamic release of LHRH or via a direct CRH-mediated inhibition of the FSH-stimulated oestrogen production in the ovary. Serotonin (5HT), precursors like tryptophan (5HTP), drugs which release 5HT or act directly on 5HT receptors stimulate HPA axis, indicating a stimulatory serotonergic influence on HPA axis function. Therefore activation of the HPA axis may reflect an elevated serotonergic tonus in the central nervous system of FMS patients.
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PMID:Neuroendocrine and hormonal perturbations and relations to the serotonergic system in fibromyalgia patients. 1102 24

A large body of data from a number of different laboratories worldwide has demonstrated a general tendency for reduced adrenocortical responsiveness in CFS. It is still not clear if this is secondary to CNS abnormalities leading to decreased activity of CRH- or AVP-producing hypothalamic neurons. Primary hypofunction of the CRH neurons has been described on the basis of genetic and environmental influences. Other pathways could secondarily influence HPA axis activity, however. For example, serotonergic and noradrenergic input acts to stimulate HPA axis activity. Deficient serotonergic activity in CFS has been suggested by some of the studies as reviewed here. In addition, hypofunction of sympathetic nervous system function has been described and could contribute to abnormalities of central components of the HPA axis. One could interpret the clinical trial of glucocorticoid replacement in patients with CFS as confirmation of adrenal insufficiency if one were convinced of a positive therapeutic effect. If patient symptoms were related to impaired activation of central components of the axis, replacing glucocorticoids would merely exacerbate symptoms caused by enhanced negative feedback. Further study of specific components of the HPA axis should ultimately clarify the reproducible abnormalities associated with a clinical picture of CFS. In contrast to CFS, the results of the different hormonal axes in FMS support the assumption that the distortion of the hormonal pattern observed can be attributed to hyperactivity of CRH neurons. This hyperactivity may be driven and sustained by stress exerted by chronic pain originating in the musculoskeletal system or by an alteration of the CNS mechanism of nociception. The elevated activity of CRH neurons also seems to cause alteration of the set point of other hormonal axes. In addition to its control of the adrenal hormones, CRH stimulates somatostatin secretion at the hypothalamic level, which, in turn, causes inhibition of growth hormone and thyroid-stimulating hormone at the pituitary level. The suppression of gonadal function may also be attributed to elevated CRH because of its ability to inhibit hypothalamic luteinizing hormone-releasing hormone release; however, a remote effect on the ovary by the inhibition of follicle-stimulating hormone-stimulated estrogen production must also be considered. Serotonin (5-HT) precursors such as tryptophan (5-HTP), drugs that release 5-HT, or drugs that act directly on 5-HT receptors stimulate the HPA axis, indicating a stimulatory effect of serotonergic input on HPA axis function. Hyperfunction of the HPA axis could also reflect an elevated serotonergic tonus in the CNS of FMS patients. The authors conclude that the observed pattern of hormonal deviations in patients with FMS is a CNS adjustment to chronic pain and stress, constitutes a specific entity of FMS, and is primarily evoked by activated CRH neurons.
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PMID:Neuroendocrine perturbations in fibromyalgia and chronic fatigue syndrome. 1108 55

Insulin, glucagon, somatostatin-14, and three structurally related molecular forms of peptide tyrosine-tyrosine (PYY) were isolated from an extract of the combined pancreas and gastrointestinal tract of the pallid sturgeon, Scaphirhynchus albus. Pallid sturgeon insulin was identical to insulin from the Russian sturgeon, Acipenser guldenstaedti, and to insulin-2 from the paddlefish, Polyodon spathula, and was approximately twofold less potent than human insulin in inhibiting the binding of [3-[(125)I] iodotyrosine-A14] human insulin to the soluble human insulin receptor. The sturgeon glucagon (HSQGMFTNDY(10)-SKYLEEKLAQ(20) EFVEWLKNGK(30)S), like the two paddlefish glucagons, contains 31 rather than 29 amino acid residues, indicative of an anomalous pathway of posttranslational processing of proglucagon. Pallid sturgeon somatostatin, identical to human somatostatin-14, was also isolated in a second molecular form containing an oxidized tryptophan residue, but [Pro(2)]somatostatin-14, previously isolated from the pituitary of A. guldenstaedti, was not identified. Sturgeon PYY (FPPKPEHPGD(10)DAPAEDVAKY(20)YTALRHYINL(30) ITRQRY.HN(2)) was also isolated in variant forms containing the substitutions (Phe(1) --> Ala) and (Ala(18) --> Val), indicative of at least two gene duplications occurring within the Acipenseriformes lineage. The amino acid sequences of the pallidsturgeon PYY peptides are appreciably different from the proposed "ancestral" PYY sequence that has otherwise been very strongly conserved among the actinopterygian and elasmobranch fish.
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PMID:Gastroenteropancreatic hormones (insulin, glucagon, somatostatin, and multiple forms of PYY) from the pallid sturgeon, Scaphirhynchus albus (Acipenseriformes). 1112

[reaction: see text] The synthesis of four bioactive analogues of the somatostatin (SRIF-14) mimetic, beta-d-glucoside (+)-2, in which the C1 indole side chain is replaced with indole surrogates, has been achieved. These congeners, possessing the naphthyl, benzothiophene, benzyl, and benzofuran substituents, were predicted to satisfy the electrostatic requirements of the tryptophan binding pocket of SRIF. Unlike the previously described C4 picolyl and pyrazinyl congeners, these ligands bind the hSST4 receptor.
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PMID:Synthesis and binding affinities of novel SRIF-mimicking beta-D-glucosides satisfying the requirement for a pi-cloud at C1. 1576 Jan 54

The application of second derivative tryptophan (Trp) fluorescence spectroscopy to characterize partially unfolded intermediates of proteins relevant to protein formulation was investigated. The second derivatives of the normalized emission scans of N-acetyl tryptophanamide (NATA), single-Trp containing proteins, somatostatin and human serum albumin (HSA), and two-Trp containing proteins previously shown to form partially unfolded intermediates, beta-lactoglobulin (beta Lg) and interferon alpha-2a (IFN alpha 2a), were studied in solution. The second derivative of NATA in water showed three bands at 340, 348 and 367 nm. The 340 nm band showed a blue shift, whereas the intensity of all three bands was affected by a decrease in solution polarity. Second derivative of single-Trp containing proteins, somatostatin and HSA, showed three negative bands, whereas, the second derivative of the two-Trp containing proteins, beta Lg and IFN alpha 2a, showed four bands, two of which lie in the 320-340 nm range. These two bands were attributed to the presence of the Trps in different microenvironments. The characteristic changes in the intensities of these two bands on addition of guanidine hydrochloride (beta Lg) and with a decrease in solution pH (IFN alpha 2a) were related to the presence of partially unfolded intermediates of these proteins. Thus, second derivative Trp fluorescence spectroscopy can be used as an important tool to identify partially unfolded states of proteins during formulation utilizing order of magnitude lower concentrations compared to such other technique as near UV CD.
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PMID:Second derivative tryptophan fluorescence spectroscopy as a tool to characterize partially unfolded intermediates of proteins. 1581 44


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