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)

The potency of several peptides and drugs as histamine liberators was assessed using the rat isolated hind limb preparation. Neurotensin (NT) and compound 48/80 (C48/80) were effective in concentrations as low as 10(-9) M and 10(-8) M, respectively. Threshold concentrations of vasoactive intestinal peptide (VIP) and substance P (SP) varied between 5 X 10(-7) to 5 X 10(-6) M while somatostatin (SS) was barely active at 6 X 10(-6) M. No histamine release could be detected following the use of high concentrations of thyrotropin releasing hormone (TRH) (6 X 10(-6) M), dynorphin (DYN) (6 X 10(-6) M) bradykinin (BK), des-Arg9-BK or bombesin (BB) (at 10(-5) M). Poly-L-Lysine and the calcium ionophore A23187 were about 100 times less active than NT. Concanavalin A (Con A) was inactive at 10(-6) M. These results indicate that NT is more potent (on a molar basis) as histamine liberator in the rat hind limb preparation (which contains a large population of cutaneous and subcutaneous mast cells) than any of the other compounds tested. Histamine release by NT was inhibited by preexposure of the rat hind limb mast cells to a high concentration of SP (1.5 X 10(-6) M). This result adds further support to the hypothesis suggesting that NT and SP might share a common mechanism of action and/or act through common receptors at least in rat mast cells.
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PMID:Potency of various peptides as histamine liberators in the rat hind limb. 241 86

The biosynthesis of somatostatin has been studied at the ultrastructural level in pancreatic islets by using rabbit antiserum against synthetic somatostatin. To document that the antiserum specifically bound preprosomatostatin, we have tested the ability of the antiserum to precipitate the product synthesized in vitro. Poly(A) enriched RNA isolated from catfish islets was translated in both the wheat germ extract and nuclease-treated reticulocyte lysate systems. It was found that the in vitro translation product, preprosomatostatin, could be recognized by the antibody against synthetic somatostatin. The morphological study was then performed by immunoelectron microscopy by using the Fab-peroxidase conjugate technique. In dog pancreatic islets, somatostatin immunoreactive reaction product was seen only in the delta cells. In these cells, they were detected on bound ribosomes, in the cisternae of the rough endoplasmic reticulum (ER) and Golgi apparatus, in the Golgi associated vesicles, and in secretory vesicles. These findings suggest that somatostatin precursor molecules are synthesized on bound ribosomes and discharged into the cisternae of the rough ER. They are then transported to the Golgi apparatus and transferred to the secretory vesicles for secretion. The different staining intensities in the secretory vesicles would suggest that the processing of the precursor molecules of somatostatin probably takes place in the secretory vesicles.
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PMID:Immunoelectron microscopic study of somatostatin biosynthesis in dog pancreas. 613 5

Poly(alkyl cyanoacrylate) nanocapsules have been used as biodegradable polymeric drug carriers for subcutaneous and peroral delivery of octreotide, a long-acting somatostatin analogue; their ability to reduce insulin secretion or prolactin secretion in response to oestrogens has been studied in adult male rats. The nanocapsules, prepared by interfacial emulsion polymerization of isobutyl cyanoacrylate, were 260 nm in diameter and incorporated 60% of octreotide. Administered subcutaneously, the octreotide-loaded (20 micrograms kg-1) nanocapsules suppressed the insulinaemia peak induced by intravenous glucose overload and depressed insulin secretion over 48 h, preventing the secretory rebound; however, glycaemia was unaffected. In parallel, the plasma octreotide concentration increased 2.7 times. Administered perorally to oestrogen-treated rats, octreotide-loaded nanocapsules (200 and 1000 micrograms kg-1) significantly improved the reduction of prolactin secretion (by 72 and 88%, respectively, compared with 32 and 54% with free octreotide) and slightly increased plasma octreotide level. Thus nanocapsules could be of interest as a biodegradable drug carrier for the administration of octreotide.
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PMID:Poly(alkyl cyanoacrylate) nanocapsules as a delivery system in the rat for octreotide, a long-acting somatostatin analogue. 936 1

The purpose of this research was to study the chemical reactivity of a somatostatin analogue, octreotide acetate, formulated in microspheres with polymers of varying molecular weight and co-monomer ratio under in vitro testing conditions. Poly(D,L-lactide-co-glycolide) (PLGA) and poly(D,L-lactide) (PLA) microspheres were prepared by a solvent extraction/evaporation method. The microspheres were characterized for drug load, impurity content, and particle size. Further, the microspheres were subjected to in vitro release testing in acetate buffer (pH 4.0) and phosphate buffered saline (PBS) (pH 7.2). In acetate buffer, 3 microsphere batches composed of low molecular weight PLGA 50:50, PLGA 85:15, and PLA polymers (< or =10 kDa) showed 100% release with minimal impurity formation (<10%). The high molecular weight PLGA 50:50 microspheres (28 kDa) displayed only 70% cumulative release in acetate buffer with significant impurity formation (approximately 24%). In PBS (pH 7.4), on the other hand, only 50% release was observed with the same low molecular weight batches (PLGA 50:50, PLGA 85:15, and PLA) with higher percentages of hydrophobic impurity formation (ie, 40%, 26%, and 10%, respectively). In addition, in PBS, the high molecular weight PLGA 50:50 microspheres showed only 20% drug release with ~66% mean impurity content. The chemically modified peptide impurities inside microspheres were structurally confirmed through Fourier transform-mass spectrometry (FT-MS) and liquid chromatography/mass spectrometry (LC-MS/MS) analyses after extraction procedures. The adduct compounds were identified as covalently modified conjugates of octreotide with lactic and glycolic acid monomers within polymeric microspheres. The data suggest that due to steric hindrance factors, polymers with greater lactide content were less amenable to the formation of adduct impurities compared with PLGA 50:50 copolymers.
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PMID:Identification of chemically modified peptide from poly(D,L-lactide-co-glycolide) microspheres under in vitro release conditions. 1519 45

Somatostatin (SS) and growth hormone-releasing hormone (GHRH) are synthesized and secreted by the hypothalamus, which can control the synthesis and secretion of the growth hormone (GH) from the hypophysis as well as regulate the GH concentrations in animals and humans. In this article, we describe the regulation of animal growth using plasmid DNA encoding both the GHRH gene and the SS gene fused with the hepatitis B surface antigen (HBsAg) gene. We constructed a series of expression plasmids to express the GHRH and HBsAg-SS fusion genes individually as well as collectively. The fusion gene and GHRH were successfully expressed in Chinese hamster ovary (CHO) cells, as proven by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting tests. Poly D, L-lactide-co-glycolic acid (PLGA) plasmid-encapsulating microspheres were prepared and injected intramuscularly into the leg skeletal muscles of rabbits. Weight gain/day and the levels of insulinlike growth factor-I (IGF-I), SS, and hepatitis B surface antibody (HBsAb) were monitored. During days 30 postinjection, increase in weight gain/day and IGF- I concentration and decrease in SS were observed in treatment groups. From days 15 to 30 postinjection, the weight gain/day significantly increased (P < 0.05) by 129.13%, 106.8%, and 72.82% relative to the control group in the co-expression GHRH and fusion gene (named P-G-HS), fusion gene (named P-HS), and GHRH (named P-G) groups, respectively. And most importantly, the P-G-HS group showed significant weight gain/day (P < 0.05) relative to the P-G and P-HS groups. A significant increase in the IGF-I concentration and decrease in the SS level relative to the control group were also observed. The results indicated that the combination of plasmid-mediated GHRH supplementation and positive immunization against SS led to more robust weight gain/day in rabbits.
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PMID:Simultaneous expression of growth hormone releasing hormone (GHRH) and hepatitis B surface antigen/somatostatin (HBsAg/SS) fusion genes in a construct in the skeletal muscle enhances rabbit weight gain. 1843 1