UNIPROT:P61278 - FACTA Search

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

The physical properties of brain and pituitary somatostatin receptors were characterized using photocrosslinking techniques. Somatostatin receptors in rat corpus striatum and anterior pituitary membranes were covalently bound to the non-reducible somatostatin analog, [125I]CGP 23996, using the crosslinking agent n-hydroxysuccinimidyl-4-azidobenzoate and ultraviolet light. In striatal membranes, a protein of 60,000 mol. wt was labeled by [125I]CGP 23996. The binding was potently inhibited by somatostatin analogs but not by other biologically active peptides. The labeling of the 60,000 mol. wt protein by [125I]CGP 23996 was diminished by guanine triphosphate gamma thiol, which is consistent with the labeling of a somatostatin receptor coupled to guanine triphosphate binding proteins. The migration of the [125I]CGP 23996 labeled 60,000 mol. wt protein in native sodium dodecyl sulfate-gels was not affected by the reducing agent dithiothreitol, indicating that there is a general lack of disulfide bridges in the striatal somatostatin receptor. The striatal somatostatin receptor was solubilized with the detergent 3-[(3-cholamidopropyl)-dimethylaminoio]-1-propanesulfonate and specifically bound to the lectin wheat germ agglutinin, suggesting that the striatal somatostatin receptor is a glycoprotein. [125I]CGP 23996 also labeled a 60,000 mol. wt protein in anterior pituitary membranes. The characteristics of [125I]CGP 23996 binding to anterior pituitary membranes were consistent with the labeling of a somatostatin receptor. Interestingly, a comparison of the [125I]CGP 23996 labeled material from striatal and anterior pituitary membranes by two-dimensional polyacrylamide gel electrophoresis revealed the presence of several striatal somatostatin receptors of varying charge (pI values between 6 and 6.5) but only a single pituitary receptor. These findings indicate that physical differences may exist between subtypes of somatostatin receptors.
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PMID:Biochemical properties of brain somatostatin receptors. 257 Mar 75

Monoclonal antibody VC1.1 is shown to stain selectively a subpopulation of GABAergic neurons in the rat cerebral cortex. Almost all VC1.1 immunoreactive cells were also GABA-like immunoreactive (GABA-LI) and parvalbumin (PV) immunoreactive, whereas they were about 30% and 65% of GABA-LI and PV-positive cells in the parietal cortex and about 13% and 32% in the occipital cortex, respectively. Although a few VC1.1 positive cells showed somatostatin-like and/or cholecystokinin-like immunoreactivities, they were exceptional (less than 1% of VC1.1 positive cells). Furthermore about 90% of VC1.1 positive cells were also stained with a lectin, Vicia villosa agglutinin, with a specific affinity for terminal N-acetylgalactosamine.
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PMID:Monoclonal antibody VC1.1 selectively stains a population of GABAergic neurons containing the calcium-binding protein parvalbumin in the rat cerebral cortex. 259 17

A detailed study of the distribution of neuropeptide Y (NPY) in the striatum of squirrel monkey (Saimiri sciureus) and cat was undertaken by means of indirect immunofluorescence and peroxidase-antiperoxidase (PAP) methods. In monkey, the NPY-immunoreactivity is homogeneously distributed along the entire extent of the caudate nucleus (CD) and putamen (PUT), while in cat marked heterogeneities are noted. In the CD of cat, the NPY-immunoreactive fibers and cell bodies are concentrated in numerous patches of various sizes, which can be readily distinguished from zones of poor NPY-immunostaining. In the CD and PUT of squirrel monkey the NPY-positive neurons are either triangular, fusiform or globular, with long and smooth dendrites branching infrequently. The numerical density of NPY-immunoreactive cell bodies is greater in the CD than in the PUT, and it increases markedly along the rostrocaudal extent of the striatum. In the rostral CD and PUT the densities are 23 cells/mm2 and 14 cells/mm2, respectively, whereas the values for caudal CD and PUT are 35 cells/mm2 and 20 cells/mm2, respectively. Quantitative measurements reveal that these NPY-immunoreactive cells belong to a single subset of striatal neurons having a maximum diameter of 19.2 +/- 0.1 micron and a cross-sectional area of 145.5 +/- 0.6 micron2 (mean +/- S.E.M.; n = 1238 CD cells and 1169 PUT cells). Furthermore, experiments combining the use of lectin-conjugated HRP as retrograde tracer with PAP immunohistochemical method demonstrate that striatal NPY-immunoreactive neurons in squirrel monkey and cat do not project outside the striatum. Finally, co-localization studies in monkey reveal that the vast majority of striatal NPY-positive neurons also contains somatostatin. These results show that the NPY-immunoreactive neurons in mammalian striatum form a subpopulation of medium-sized interneurons containing somatostatin.
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PMID:Neuropeptide Y-immunoreactive neurons in the striatum of cat and monkey: morphological characteristics, intrinsic organization and co-localization with somatostatin. 287

The receptor for somatostatin present in rat pancreatic plasma membranes was characterized by affinity labeling with [125I-Tyr11]somatostatin utilizing three different heterobifunctional cross-linking agents: N-5-azido-2-nitrobenzoyloxy-succinimide, N-succinimidyl 6-(4-azido 2'-nitrophenylamine)hexanoate, and N-hydroxysuccinimidyl 4-azido-benzoate. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed a broad band of Mr = 92,000 when any of the three cross-linkers was used; N-succinimidyl 6-(4-azido 2'-nitrophenylamine), however, was most efficient. Labeling of the Mr = 92,000 protein band was not affected by reducing agents but was sensitive to somatostatin and guanine nucleotides, particularly GTP gamma S, at concentrations which reduced binding to the receptor. The affinity-labeled protein could be solubilized completely with Zwittergent 3-12, partially with Triton X-100 and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, and poorly with Zwittergent 3-08 and digitonin. When exposed to agarose-coupled lectins, the detergent solubilized, labeled Mr = 92,000 protein was completely adsorbed to wheat germ agglutinin, partially to ricin communis II, and not at all to concanavalin A or lotus or lentil lectin. The Mr = 92,000 protein bound to wheat germ agglutinin-agarose was not eluted by N-acetylglucosamine but was by triacetylchitotriose, providing a considerable purification of the somatostatin receptor. These data allow us to conclude that the somatostatin receptor is a monomeric glycoprotein with an Mr = 90,000 binding subunit which probably contains a polymeric arrangement of N-acetylglucosamine residues.
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PMID:Characterization of covalently cross-linked pancreatic somatostatin receptors. 287 90

The somatostatin receptors on rat pancreatic acinar membranes were demonstrated by use of a radioiodinated (125I-) analogue of somatostatin (SMS 204-090 or [Tyr3]SMS). The tracer was found to bind to the receptor with a Kd of 58 pM. The number of sites detected by this tracer (4.7 pmol/mg of protein) was 5-10 times higher than the number of sites previously found with other tracers. Since the level of non-specific binding was also very low as compared with findings with other tracers, 125I-204-090 might be of interest in future attempts to characterize the somatostatin receptors in the pancreas. The prelabelled membranes were solubilized with 1% CHAPS, and the solubilized complexes were found to adsorb to wheat-germ-agglutinin-coupled agarose, from which they could be eluted with 4 mM-triacetylchitotriose. The complexes within this eluate were shown by gel filtration on Trisacryl GF-2000 to have an Mr of about 400,000. The dissociation of the complexes was augmented both within the membranes as well as in the solubilized state by incubation with the GTP analogue guanosine 5'-[gamma-thio]triphosphate, indicating that the complexes are probably functionally linked to a guanine-nucleotide-binding regulatory protein. After SDS/slab-gel electrophoresis and autoradiography of cross-linked complexes after treatment with the heterobifunctional reagent N-5-azido-2-nitrobenzoyloxysuccinimide, a broad band occurred at approximately Mr 90,000 both in the membranes and in the eluates of complexes after lectin-adsorption chromatography. We conclude that the augmentation of the number of detectable sites for binding of somatostatin, as well as the very low level of non-specific binding obtained by the use of 125I-[Tyr3]SMS as tracer, has made it possible for us to demonstrate the solubilization of the somatostatin receptor in conjunction with its ligand and a GTP-binding regulatory protein, and we have succeeded in cross-linking 125I-[Tyr3]SMS to a binding subunit of Mr 90,000 in the membranes and in demonstrating the presence of the same labelled binding subunit within complexes solubilized and chromatographed on a lectin column before cross-linking.
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PMID:Molecular characterization of the solubilized receptor of somatostatin from rat pancreatic acinar membranes. 290 59

The course, distribution, and possible neurotransmitter specificity of a projection from the lateral hypothalamic area (LHA) and zona incerta to the hippocampal formation (dentate gyrus, Ammon's horn, subicular region, and entorhinal area) and spinal cord were examined anatomically in the adult rat. First, small injections of the fluorescent tracer fast blue were made into either the septal part of the dentate gyrus and Ammon's horn or the entorhinal area, and the distribution of retrogradely labeled cells was plotted. In each experiment many cells were labeled in the LHA and zona incerta, and little evidence for a topographically organized projection to different parts of the hippocampal formation was found. Second, a combined retrograde transport-immunofluorescence method was used to show that some 95% of the fast blue-labeled neurons in the LHA and zona incerta were also stained with an antiserum to the opiate peptide alpha-melanocyte-stimulating hormone (alpha MSH), but not an antiserum to adrenocorticotropin (ACTH)1-24. It was also found that small numbers of retrogradely labeled neurons were stained with antisera to somatostatin 14 and 28, dynorphin (1-17), and angiotensin II. Third, the distribution of alpha MSH-immunoreactive fibers was plotted, and they were found to form a diffusely organized plexus throughout all of the subfields of the hippocampal formation. These fibers were virtually eliminated after transections of the fimbria and the region between the entorhinal area and the caudal amygdala. Forth, the course of fibers from the LHA and zona incerta was examined with the anterogradely transported lectin Phaseolus Vulgaris Leucoagglutinin (PHAL). Such fibers reach the hippocampal formation by a dorsal route through the septal region and fimbria, and by a ventral route through the amygdala. And fifth, double retrograde transport and immunohistochemical methods were used to show that at least some alpha MSH-stained neurons in the LHA and zona incerta give rise to collaterals that innervate both the hippocampal formation and the spinal cord. Alpha MSH-stained fibers in the spinal cord also form a widely scattered plexus with no obvious circumscribed terminal fields. It is suggested that the diffusely organized projection from the LHA to the cerebral cortex and spinal cord may play a role in the general arousal associated with a variety of motivated behaviors.
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PMID:A diffuse alpha MSH-immunoreactive projection to the hippocampus and spinal cord from individual neurons in the lateral hypothalamic area and zona incerta. 632 9

We examined the chronic (72 h) effects of 30 ng/ml recombinant murine tumor necrosis factor (TNF)-alpha on release of immunoreactive growth hormone (GH), prolactin (PRL), thyrotropin (TSH), and TSH glycosylation, as assessed by lectin binding, in cultured rat anterior pituitary cells. In cultured cells from adult female rats, TNF-alpha significantly suppressed basal and GH-releasing hormone (GRH)-stimulated GH release. TNF-alpha also suppressed basal PRL release and completely abolished the PRL response to TRH (0.1-10 nM). Whereas TNF-alpha reduced basal TSH release, it significantly enhanced the maximal TSH response to TRH. TNF-alpha did not affect the concanavalin A and lentil lectin binding of TSH accumulated in the medium during the 4-day culture, but significantly decreased the lentil lectin binding of TSH released in response to acute TRH stimulation. TNF-alpha significantly enhanced the inhibitory effect of somatostatin on stimulated PRL release, but not on GH or TSH release. Compared to cell cultures from adult female rats, in anterior pituitary cell cultures from 12-day-old rats the effects of prolonged exposure to TNF-alpha on hormone release were diminished or absent. Pituitary hormone release was unaffected by acute (3 h) exposure to TNF-alpha. These results demonstrate a direct effect of TNF-alpha on anterior pituitary hormone release, which is cell-type specific and age dependent.
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PMID:Prolonged effects of tumor necrosis factor-alpha on anterior pituitary hormone release. 747 97

The subpopulations were compared of neurons in human dorsal root ganglia (DRG), as substance P, identified by somatostatin, Glycine max lectin (SBA) specific to terminal N-acetylgalactosamine, and Ulex europaeus I agglutinin (UEA-I) specific to L-fucose. The lectins and neuropeptides all bound to neurons of small diameter. Furthermore, the majority of the SBA binding neurons or somatostatin positive neurons were also UEA-I binding neurons. However, SBA binding neurons were not colocalized with somatostatin or substance P. Less than 20% of substance P positive neurons showed colocalization with L-fucosyl residues, and approximately 10% of L-fucosyl residues showed colocalization with substance P. Our results suggest that both L-fucose and terminal N-acetylgalactosamine containing neurons in the human DRG are subjected to different subpopulations from substance P or somatostatin positive neurons.
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PMID:Differential localization of lectin binding sites and neuropeptides in human dorsal root ganglia. 753 Nov 91

The effects of somatostatin on histamine release were studied using primary cultures of canine oxyntic mucosal cells in which mast cell content was reduced by density gradient. The S6 monoclonal antibody to somatostatin, but not control antibodies, enhanced gastrin-stimulated histamine release. In the presence of S6, the somatostatin analogue SMS-201-995 (10(-7) M) inhibited gastrin-stimulated histamine release by 95%. The dose producing 50% inhibition for this inhibition was approximately 3 x 10(-10) M and was completely reversed by pertussis toxin treatment. In contrast to somatostatin, epinephrine failed to inhibit this gastrin stimulation. However, the lectin concanavalin A (ConA) also stimulated histamine release from these cultures, and this response was inhibited by epinephrine but not by somatostatin. Thus somatostatin selectively inhibited the gastrin-responsive histamine pool, which presumably is stored in oxyntic mucosal endocrine cells. In contrast, epinephrine selectively inhibits histamine release from the ConA-sensitive pool, which is presumably stored in mast cells. Furthermore, enhancement of gastrin-stimulated histamine release by immunoneutralization of somatostatin indicates an important role for endogenous somatostatin as a paracrine inhibitor of non-mast cell histamine release.
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PMID:Endogenous somatostatin inhibits histamine release from canine gastric mucosal cells in primary culture. 769 44

Peptide-23 is a 16-kilodalton protein secreted by rat pituitary cells that was first identified because it was regulated by GRF and somatostatin in a similar fashion to GH. Cloning of peptide-23 complementary DNA revealed that it is identical to pancreatitis-associated protein (PAP) and a member of the c-lectin gene family. We examined the expression of peptide-23/PAP and a structurally related protein, pancreatic stone protein (PSP/reg), in the rat gastrointestinal tract. Here we report age-related changes in the expression and GRF regulation of peptide-23. Both peptide-23/PAP messenger RNA (mRNA) and PSP/reg mRNA were virtually undetectable in the small intestine of newborn and 1- and 2-week-old rats. A dramatic increase in the expression of both genes was seen at the time of weaning in the third week postpartum. The abundance of both of these mRNA decreases after 3 and 6 months of age. Peptide-23/PAP mRNA is most abundant in the ileum, whereas PSP/reg is maximally expressed in the pancreas and duodenum. Human GRF analog pellets were implanted sc into adult male rats for 2 weeks to study the chronic effects of GRF on the expression of these genes. Both peptide-23/PAP and PSP/reg mRNA levels in duodenum and jejunum were increased in these rats compared with levels in control rats. However, no increase in peptide-23/PAP mRNA in response to GRF treatment was seen in the ileum, where the level of expression of this gene is very high, and GRF had no effect on peptide-23/PSP expression in the heart, pituitary, or hypothalamus, where expression is normally undetectable. In situ hybridization was used to localize peptide-23/PSP in the small intestine and pancreas of GRF-treated rats. An increase in peptide-23/PAP mRNA was restricted to acinar cells close to islets, whereas little expression was seen in acinar cells distant from islets, suggesting that either peptide-23/PAP may have some paracrine action on the islets, or alternatively, an islet-derived factor may function as a paracrine modulator of peptide-23/PAP expression. These data demonstrate that GRF modulates peptide-23/PAP expression in the gastrointestinal tract in a similar fashion to that previously reported for pituitary cells in primary culture.
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PMID:Age-related changes in peptide-23/pancreatitis-associated protein and pancreatic stone protein/reg gene expression in the rat and regulation by growth hormone-releasing hormone. 772 Jun 28

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