Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UNIPROT:P61278 (somatostatin)
22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thyroliberin (TRH), vasoactive intestinal peptide (VIP) and somatostatin (SRIF) act through receptors that are coupled to guanine nucleotide-binding regulatory proteins (G proteins). Regulation of hormone action may occur at the level of G protein coupling to the receptor or effector systems. In this study we demonstrate that prolonged exposure (for up to 48 hr) of cultured rat pituitary adenoma GH3 cells to these hormones caused homologous and to some extent heterologous attenuation of the adenylyl cyclase (AC) (EC 4.6.1.1) responsiveness. In addition, TRH and SRIF diminished both TRH- and guanosine 5'-[beta gamma-imido]-triphosphate-enhanced phospholipase C (PLC) (EC 3.1.4.3) activity within the same time-course. Measurements of cells membrane levels of Gs protein alpha-subunit (Gs alpha), G(i)-1 alpha/G(i)-2 alpha, G(i)-3 alpha, G(o) alpha and G beta by immunoblotting were performed. TRH and VIP upregulated levels of all G proteins except G(o) alpha and G beta. In contrast, SRIF caused a marked reduction of G beta levels. Thus, TRH and VIP, both acting through Gs, both modulated the alpha-subunit levels of this signal transducer, whereas SRIF, which possibly acts through G(i)-2, did not change the steady state level of G(i)-2 alpha. The actions of TRH, VIP and SRIF are multifaceted at the G protein level, where modulations of subtypes not directly involved in their actions may occur. These findings emphasize the complexity expected to be found in the in vivo situation.
...
PMID:Hypothalamic hormones modulate G protein levels and second messenger responsiveness in GH3 rat pituitary tumour cells. 135 62

Calretinin and calbindin-D28k are two calcium-binding proteins which are present in separate populations of interneurons in cerebral cortex and hippocampus. To identify these cells with the populations expressing different transmitters, two-colour immunofluorescence was done with antibodies against the calcium-binding proteins plus antibodies against vasoactive intestinal peptide (VIP), somatostatin (SRIF), or gamma-aminobutyric acid (GABA). In neocortex, calretinin is partially co-localized with VIP (especially in the deeper layers) and is not co-localized with SRIF. Calbindin is largely co-localized with SRIF, and not with VIP. Both calretinin and calbindin are partially co-localized with GABA. In piriform and entorhinal cortex, the patterns resemble those in neocortex. In hippocampus, preliminary data indicate greater heterogeneity, especially in the ventral part; at least a few double-positive cells are present for every combination of calcium-binding protein and neuropeptide. These results expand the known diversity of local-circuit neurons in cortical regions.
...
PMID:Immunohistochemical markers in rat cortex: co-localization of calretinin and calbindin-D28k with neuropeptides and GABA. 135 60

The dual regulation of cyclic AMP levels in rat peritoneal macrophages incubated with somatostatin, vasoactive intestinal peptide (VIP), and isoproterenol was studied. Somatostatin exerted a non-competitive inhibition of the stimulatory effect of VIP and isoproterenol on cyclic AMP production. In addition, somatostatin inhibited basal cyclic AMP levels. Our results suggest that somatostatin and VIP may modulate the immune response acting, through cyclic AMP, on macrophage functions.
...
PMID:Somatostatin inhibition of VIP- and isoproterenol-stimulated cyclic AMP production in rat peritoneal macrophages. 135 81

Somatostatin (SS) receptors in membranes from ovine retinas were examined using 125I-Tyr11-SS as a ligand. Receptor binding was rapid, specific, saturable, reversible and dependent on temperature and membrane concentration. Conditions of apparent equilibrium were obtained at 25 degrees C after a 45 min incubation in the presence of about 0.25 mg membrane protein/ml. Native SS competitively inhibited the binding of 125I-Tyr11-SS in the range of 0.01-10 nM, and half-maximal inhibition was observed at 0.2 nM SS. Scatchard analysis of these data suggested the existence of a single population of SS receptors with a dissociation constant of 0.23 +/- 0.03 nM and a maximum binding capacity of 84 +/- 6 fmol/mg protein. The binding of 125I-Tyr11-SS was inhibited by various synthetic SS analogs in a dose-dependent manner whereas peptides unrelated to SS did not show practically any effect even at concentrations as high as 10(-6) M. SS receptor occupancy appears to be coupled to inhibition of adenylate cyclase activity by a guanine nucleotide-binding regulatory protein, as suggested by the facts that: (a) SS noncompetitively inhibited the stimulatory effect of vasoactive intestinal peptide (VIP) (3 x 10(-7) M) on membrane adenylate cyclase activity but it did not alter basal enzyme activity; and (b) the addition of guanosine 5'-triphosphate (GTP) (10(-5) M) decreased the specific binding of 125I-Tyr11-SS to 26.6% of the control value due to a decrease in SS receptor affinity. The present results support the hypothesis that SS may contribute to the physiological regulation of the functions of the retina.
...
PMID:Somatostatin binding and modulation of adenylate cyclase in ovine retina membranes. 136 Sep 27

This study demonstrates the dual regulation by somatostatin of vasoactive intestinal peptide (VIP)-stimulated and forskolin-stimulated cyclic AMP accumulation by isolated rat intestinal epithelial cells. Somatostatin non-competitively inhibited (IC50 = 1 microM) the stimulatory effect of VIP on cyclic AMP accumulation, suggesting that the two neuropeptides act through separate receptors. The cyclic AMP accumulation produced by forskolin (a diterpene that stimulates directly the catalytic subunit of adenylate cyclase) was also inhibited by somatostatin in a dose-dependent manner. However, somatostatin did not modify the stimulatory effect of VIP on adenylate cyclase activity in a membrane preparation from the same cells, making it difficult to explain the mechanism of somatostatin action at this level. The data presented here suggest that somatostatin may play a physiological role in the regulation of nutrient absorption and the release of gut hormones or exocrine secretions by intestinal epithelial cells through the modulation of cyclic AMP production.
...
PMID:Somatostatin inhibits VIP- and forskolin-stimulated cyclic AMP accumulation in enterocytes from rat jejunum. 136 40

Specimens of the sigmoid colon were obtained from male and female patients (n = 11) with carcinoma of the colon or rectum and studied immunohistochemically for vasoactive intestinal polypeptide-, somatostatin-, substance P-, neuropeptide Y-, calcitonin gene-related peptide-, met- and leu-enkephalin-, 5-hydroxytryptamine-, and dopamine beta-hydroxylase-containing nerves. In the subdivisions of the submucous plexus (namely, Schabadasch's, Meissner's, and the intermediate plexuses), substance P- and vasoactive intestinal polypeptide-immunoreactive nerve fibers were the most numerous, and equal densities of these nerves were found in all three layers. In contrast, few neuropeptide Y-, met-enkephalin-, leu-enkephalin-, calcitonin gene-related peptide-, somatostatin-, 5-hydroxytryptamine-, and dopamine beta-hydroxylase-immunoreactive nerves were found in these regions. The nerve cell bodies of the submucous plexus contained vasoactive intestinal polypeptide, substance P, leu-enkephalin, somatostatin, and 5-hydroxytryptamine but not neuropeptide Y, met-enkephalin, calcitonin gene-related peptide, and dopamine beta-hydroxylase. Vasoactive intestinal polypeptide-containing nerve cell bodies were found in all three subdivisions. Substance P-, leu-enkephalin-, and somatostatin-immunoreactive nerve cell bodies were found in Schabadasch's plexus and the intermediate region of the submucous plexus, but they were absent from Meissner's plexus; 5-hydroxytryptamine-containing nerve cell bodies were only observed in Schabadasch's plexus. The possible function of the neuropeptide-, dopamine beta-hydroxylase-, and 5-hydroxytryptamine-containing neurons in the different layers of the submucous plexus is discussed.
...
PMID:Peptide-containing neurons in different regions of the submucous plexus of human sigmoid colon. 848 77

We examined the effects of ciliary neurotrophic factor (CNTF) and depolarization, two environmental signals that influence noradrenergic and cholinergic function, on neuropeptide expression by cultured sympathetic neurons. Sciatic nerve extract, a rich source of CNTF, increased levels of vasoactive intestinal peptide (VIP), substance P, and somatostatin severalfold while significantly reducing levels of neuropeptide Y (NPY). No change was observed in the levels of leu-enkephalin (L-Enk). These effects were abolished by immunoprecipitation of CNTF-like molecules from the extract with an antiserum raised against recombinant CNTF, and recombinant CNTF caused changes in neuropeptide levels similar to those of sciatic nerve extract. Alterations in neuropeptide levels by CNTF were dose-dependent, with maximal induction at concentrations of 5-25 ng/ml. Peptide levels were altered after only 3 days of CNTF exposure and continued to change for 14 days. Depolarization of sympathetic neuron cultures with elevated potassium elicited a different spectrum of effects; it increased VIP and NPY content but did not alter substance P, somatostatin, or L-Enk. Depolarization is known to block cholinergic induction in response to heart cell conditioned medium and we found that it blocked the induction of choline acetyltransferase (ChAT) and peptides by recombinant cholinergic differentiation factor/leukemia inhibitory factor (CDF/LIF). In contrast, it did not antagonize the effects of CNTF on either ChAT activity or neuropeptide expression. Thus, while CNTF has effects on neurotransmitter properties similar to those previously reported for CDF/LIF, the actions of these two factors are differentially modulated by depolarization, suggesting that the mechanisms of cholinergic and neuropeptide induction for the two factors differ. In addition, in contrast to CDF/LIF, CNTF did not alter levels of ChAT, VIP, substance P, or somatostatin in cultured dorsal root ganglion neurons. These observations indicate that CNTF and depolarization affect the expression of neuropeptides by sympathetic neurons and provide evidence for an overlapping yet distinct spectrum of actions of the two neuronal differentiation factors, CNTF and CDF/LIF.
...
PMID:Effects of ciliary neurotrophic factor (CNTF) and depolarization on neuropeptide expression in cultured sympathetic neurons. 137 70

We studied the effect of vasoactive intestinal peptide (VIP), somatostatin (SOM), and substance P (SP) on IL-4-stimulated human IgE and IgG subclass production. VIP and SOM, but not SP, inhibited IgE production without affecting IgM or IgA production by mononuclear cells (MNC) from nonatopic donors from 10 pM to 10 nM. These neuropeptides also differentially modulated IgG subclass production. While IgG1 production was not affected by VIP, SOM, or SP, all of the neuropeptides enhanced IgG2 production. By contrast, SOM and SP, but not VIP, inhibited IgG3 production, whereas VIP and SP, but not SOM, enhanced IgG4 production. The effect by neuropeptides was specific since each peptide effect was specifically blocked by each antagonist. To achieve this effect, neuropeptides must be added at the start of the culture and be present throughout the entire culture period. The inhibition of IgE production was not mediated by known inhibitors of IgE production, IFN-gamma or PGE2, because the addition of anti-IFN-gamma mAb (10 micrograms/ml) or indomethacin (0.1 microM) did not overcome the inhibition of IgE production. In contrast to MNC, neuropeptides did not affect IgG subclass production in purified B cells. IgE production was not induced by IL-4 in purified B cells. Neuropeptides also failed to modulate IgG subclass production in cultures of B cells with either T cells or monocytes. However, they modulated IgE production and IgG subclass production in B cells in the presence of T cells and monocytes. In purified B cells, IL-4 plus anti-CD40 mAb induced IgE production which was not inhibited by VIP or SOM. However, VIP or SOM, but not SP, inhibited IgE production in B cells cultured with both T cells and monocytes. Finally, the mechanism of modulation of IgE and IgG4 production was dependent on IL-4-induced switching, since neuropeptides modulated IgG4 and IgE production in surface IgG4-negative (sIgG4-) and sIgE- B cells, respectively. In contrast, modulation of IgG2 and IgG3 production was not due to switching, since neuropeptides did not affect either IgG2 or IgG3 production in sIgG2- or sIgG3- B cells, respectively.
...
PMID:Differential effect of vasoactive intestinal peptide, somatostatin, and substance P on human IgE and IgG subclass production. 138 70

The hypothalamo-neurohypophyseal tract is known to contain the classical neurohypophyseal hormones vasopressin and oxytocin. Additionally, dynorphin, methionine- and leucine-enkephalin, cholecystokinin (CCK), corticotropin-releasing factor (CRF), and galanin are co-stored with vasopressin and/or oxytocin. Recent immunohistochemical studies have revealed the existence of a low to moderate number of substance P-, vasoactive intestinal peptide (VIP)-, neuropeptide Y (NPY)- and somatostatin-immunoreactive nerve fibers within the rat neurohypophysis. VIP-, substance P- and NPY-immunoreactive fibers were distributed throughout the organ, whereas somatostatin-immunoreactive fibers were present in the proximal part of the organ. The positive nerve endings were either large in size resembling classical nerve terminals related to perivascular spaces, or smaller similar to peptidergic fibers as described in the CNS. These results indicate that these neuropeptides may be either co-stored with the classical neurohypophyseal hormones or contained in another system of afferents to the organ. The probably distinct functional roles of these neuropeptides in the physiology of the neurohypophysis are discussed.
...
PMID:Non-vasopressinergic, non-oxytocinergic neuropeptides in the rat hypothalamo-neurohypophyseal tract: experimental immunohistochemical studies. 138 83

The present work was undertaken to determine by immunocytochemical methods which of the putative enteric neurotransmitters are contained in axons supplying the guinea-pig taenia coli and what proportion of axons is accounted for by the presence of these substances. Numerous fibres displayed immunoreactivity for dynorphin (DYN), enkephalin (ENK), gamma-aminobutyric acid (GABA), nitric oxide synthase (NOS), substance P (SP) and vasoactive intestinal peptide (VIP), but, in contrast to other gut regions, fibres showing immunoreactivity for gastrin-releasing peptide, galanin and neuropeptide Y were rare in the taenia. Fibres reactive for calbindin, calcitonin gene-related peptide, cholecystokinin, 5-hydroxytryptamine and somatostatin were also rare. Tyrosine hydroxylase-like immunoreactivity (TH-LI) was present in numerous fibres that disappeared after extrinsic denervation, a procedure that did not detectably affect any of the other major groups of fibres. Simultaneous staining of extrinsically denervated preparations revealed that SP-LI and VIP-LI were located in separate fibres, and ultrastructural studies showed these to be 58% and 33% of intrinsic fibres supplying the muscle. Immunoreactivity for the general marker, neuron-specific enolase, was located in 95-98% of axons. ENK-LI and DYN-LI were in the same axons, and similar proportions of the fibres with either SP-LI or VIP-LI, about 85%, contained immunoreactivity for ENK and DYN. All VIP-LI fibres, but no SP-LI fibres, were reactive for NOS. The results imply that the taenia of the guinea-pig caecum is innervated by two major groups of enteric neurons: (i) excitatory neurons that contain ACh, SP, other tachykinins, and, in most cases, DYN-LI and ENK-LI; and (ii) inhibitory neurons that contain NOS-LI, VIP-LI, in most cases, the two opioids and, quite probably, ATP as a transmitter. GABA-LI is contained in a smaller population of intrinsic axons. Even though the taenia represents one of the simplest tissues for examining transmission from enteric neurons to intestinal muscle, it shares some of the complexity of other regions, in that four major axon types supply the muscle and both the enteric excitatory and enteric inhibitory neurons contain multiple transmitters.
...
PMID:Light- and electron-microscopic immunochemical analysis of nerve fibre types innervating the taenia of the guinea-pig caecum. 138 81


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---