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)

Acutely increased intra-abdominal pressure (IAP) may lead to abdominal compartment syndrome (ACS), which ischaemia/reperfusion (I/R) injury plays an important role. The main goal of the management of ACS is to lower the intra-abdominal pressure despite reperfusion injury. Octreotide (OCT), a synthetic somatostatin analogue, lowers the splanchnic perfusion. The aim of this study was to investigate whether OCT improves the reperfusion injury after decompression of acute abdominal hypertension.Under anesthesia, a catheter was inserted intraperitoneally and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1h. In the I/R group, pressure applied for an hour was decompressed and 1h reperfusion period was allowed. In another group of I/R, OCT was administered (50 microg/kg i.p.) immediately before the decompression of IAP. The results demonstrate that kidney and lung tissues of malondialdehyde (MDA; an end product of lipid peroxidation) levels and myeloperoxidase (MPO; index of tissue neutrophil infiltration) activity were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in I/R group (P<0.001). Moreover, OCT treatment applied in the I/R group reduced the elevations in blood urea nitrogen (BUN) and serum creatinine levels. Our results implicate that IAP causes oxidative organ damage and OCT, by reducing splanchnic perfusion and controlling the reperfusion of abdominal organs, could improve the reperfusion-induced oxidative damage. Therefore, its therapeutic role as a "reperfusion injury-limiting" agent must be further elucidated in IAP-induced abdominal organ injury.
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PMID:Octreotide: a new approach to the management of acute abdominal hypertension. 1470 53

Hepatic metastases are frequently encountered in patients with digestive endocrine tumors and their presence plays an important role in quality of life and overall prognosis. Surgery is the treatment method of choice for hepatic metastases but this is frequently impossible due to the extent of disease. Systemic chemotherapy is offered to patients with diffuse and/or progressive liver metastases but results are disappointing especially in patients with metastases of midgut origin. In the latter patients with carcinoid syndrome, somatostatin analogs are frequently initially effective but their efficacy wanes due to disease progression and development of tachyphylaxis. Other therapeutic options in the treatment of hepatic metastases are locoregional strategies where vascular occlusion induces ischemia in these highly vascular tumors using either surgical or radiological techniques. Available methods include surgical ligation of the hepatic artery, transient hepatic ischemia or sequential hepatic arterialization. Trans-catheter arterial chemoembolization has proven effective in terms of long palliation and objective tumor responses. Other treatments aimed at regional destruction either alone or in combination with surgery include radiofrequency ablation and cryotherapy. The latter are usually important adjuncts to surgery and are usually reserved for limited disease.
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PMID:Ablative therapies for liver metastases of digestive endocrine tumours. 1471 59

Ischemia/reperfusion injury plays an important role in the pathogenesis of abdominal compartment syndrome, which is characterized by increased intra-abdominal pressure. The aim of this study was to investigate whether octreotide, a synthetic somatostatin analogue, improves the reperfusion injury after decompression of acute abdominal hypertension. This study was carried out in Wistar albino rats. With the rats under anesthesia, an arterial catheter was inserted intraperioneally and with the use of an aneroid manometer connected to the catheter, intra-abdominal pressure was kept at 20 mm Hg (ischemia group) for 1 hour. In the ischemia/reperfusion group, pressure applied for 1 hour was decompressed and a 1-hour reperfusion period was allowed. In another ischemia/reperfusion group, octreotide was administered (50 microg/kg intraperitoneally) immediately before the decompression of intra-abdominal pressure. At the end of the experiment, liver and intestinal tissues were taken and malondialdehyde (an index of lipid peroxidation) and glutathione (a key to antioxidant) levels and myeloperoxidase (an index of tissue neutrophil infiltration) activity were estimated. The results demonstrated that tissue levels of malondialdehyde and myeloperoxidase activity were elevated, whereas glutathione levels were reduced in both the ischemia and ischemia/reperfusion groups. Octreotide treatment reversed these oxidant responses. In conclusion, increased intra-abdominal pressure causes oxidative organ damage and octreotide, by controlling the reperfusion of abdominal organs and inhibiting neutrophil infiltration, could improve the reperfusion-induced oxidative damage. Therefore its therapeutic role as a "reperfusion injury-limiting" agent must be further elucidated in intra-aortic pressure-induced abdominal organ injury.
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PMID:Octreotide improves reperfusion-induced oxidative injury in acute abdominal hypertension in rats. 1474 43

The role of somatostatin and growth hormone in eye diseases recently became a matter of interest because of its link with proliferative diabetic retinopathy. In diabetic patients the pathologic proliferation of blood vessels as a result of retinal ischemia is a major cause of blindness. The hypoxic portions of the retina release angiogenic factors, stimulating neovascularization. Somatostatin is a natural peptide hormone that affects the release of a number of other hormones, such as growth hormone, glucagon, insulin and gastrin. The somatostatin analog promises to be safe and effective treatment for severe diabetic retinopathy. This compound has been shown to block the local and systemic production of insulin-like growth factor 1 and growth hormone, which promote the angiogenesis and endothelial cell proliferation associated with proliferative retinopathy. Several studies have confirmed that using somatostatin analogs to block insulin-like growth factor 1 production is effective in reducing neovascularization and preventing disease progression to proliferative stage of diabetic retinopathy. Long-acting somatostatin analogs are currently being tested for the treatment of diabetic retinopathy. The development of somatostatin analogs with increased selectivity for receptor subtypes will provide improved outcomes in the management of patients with diabetic retinopathy.
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PMID:Diabetes mellitus and retinopathy. 1507 18

Hepatic metastases are frequent in patients with gastroenteropancreatic (GEP) endocrine tumors. The presence of hepatic metastases affects overall prognosis and quality of life especially in the presence of debilitating functional syndromes. Surgery, although the method of choice for hepatic metastases, is usually impossible due to disease extent. Results of systemic chemotherapy are also disappointing especially in patients with metastases from midgut GEP tumors. These latter patients usually have carcinoid syndrome which can be controlled by somatostatin analogues. Other therapeutic options in the treatment of highly vascular liver metastases from GEP tumors are locoregional strategies by inducing vascular occlusion resulting in ischemia and necrosis of tumoral tissue. Surgical ligation of the hepatic artery or transient hepatic ischemia has been replaced by transcatheter arterial chemoembolization (TACE). TACE has proven effective in controlling symptoms and gives objective tumor response in about half of patients. Other regional destructive methods, used either alone or in combination with surgery, include radiofrequency ablation and cryotherapy. The latter strategies are poorly evaluated to date and are usually adjuncts to surgery and reserved for limited disease.
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PMID:Ablative therapies for liver metastases of gastroenteropancreatic endocrine tumors. 1547 22

Transient retinal ischemia induces loss of retinal ganglion cells, supporting the hypothesis that ischemic conditions contribute to the induction and progression of glaucoma. However, after 60 min of ischemia, also amacrine cells are lost from the inner nuclear layer. The main goal was to determine the relative vulnerability of various amacrine subpopulations by measuring the levels of transcripts that are known to be specifically expressed by different amacrine subpopulations. A 60-min ischemic period was administered to the rat eye by raising the intraocular pressure, followed by a reperfusion period lasting between 2 h and 4 weeks. Total RNA was isolated from the whole retina and expression levels were assessed by real-time quantitative polymerase chain reaction (qPCR). Retinal ischemia/reperfusion has differential effects on the levels of the various transcripts. Three main patterns of changes were identified. (i) A gradual decrease of transcript level without recovery was observed for parvalbumin; this transcript is expressed by the glycinergic AII cells. (ii) A gradual reduction to different levels at 72 h of reperfusion followed by a partial or complete recovery (glycine transporter 1, glutamate decarboxylase, calretinin, and several other transcripts). The glycinergic amacrine cell markers recovered to 65-75% of the control level, while the main GABAergic markers had completely recovered at 4 weeks. (iii) No significant changes of transcript levels were found for markers of several smaller GABAergic subpopulations [including substance P (Tac1), somatostatin, and others]. Expression levels of photoreceptor-, horizontal cell-, and bipolar cell-specific transcripts were not altered. These patterns were confirmed by a cluster analysis of the data. Based on gene expression levels, it may be concluded that amacrine cells are vulnerable to ischemic insults and that the glycinergic amacrine cells are relatively more sensitive to ischemia than the GABAergic population. In particular, the extensive loss of the parvalbumin-containing AII amacrine cells, which serve in the rod pathway, may have functional implications for vision under scotopic conditions. In the accompanying paper [F. Dijk and W. Kamphuis, An immunocytochemical study on specific amacrine subpopulations in the rat retina after ischemia, Brain Res. (2004).], the results are evaluated at the protein level by immunostaining for a selection of the amacrine cell markers.
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PMID:Differential effects of ischemia/reperfusion on amacrine cell subtype-specific transcript levels in the rat retina. 1548 81

Somatostatin receptor 2 (SSTR2) mediates neuromodulatory signals of somatostatin and cortistatin in the cerebral cortex. Recently, SSTR2 has been shown to enhance conserved death ligand- and mitochondria-mediated apoptotic pathways in non-neuronal cells. Whether somatostatin receptors are activated in cerebrocortical neurons and contribute to neurodegeneration after experimental focal ischemia was unknown until now. Here we examined internalization of SSTR2 in a rat model of middle cerebral artery occlusion (MCAO) by confocal microscopy. At 3 and 6 hr after MCAO, SSTR2 was internalized excessively in cerebrocortical neurons adjacent to the infarct, which was prevented by intracerebroventricular application of the SSTR2-selective antagonist BIM-23627. SSTR2 internalization was associated with a transient depletion of somatostatin from axonal terminals and increased expression of SSTR2 mRNA. The initial loss of somatostatin was followed by an increase in somatostatin mRNA levels, whereas cortistatin mRNA expression was decreased. In SSTR2-deficient mice with lacZ under the control of the SSTR2 promoter, MCAO-induced upregulation of SSTR2 gene expression was less pronounced than in wild types. SSTR2-deficient mice exhibited a 40% reduction of infarct size after permanent distal MCAO and a 63% reduction after transient proximal MCAO. In summary, we provide direct evidence for activation of SSTR2 by an endogenous ligand after focal ischemia. Activation of functional SSTR2 receptors contributes to increased SSTR2 gene expression and postischemic neurodegeneration.
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PMID:Somatostatin receptor 2 is activated in cortical neurons and contributes to neurodegeneration after focal ischemia. 1560 46

We tested the hypothesis that octreotide, a somatostatin analogue, can mimic ischemic preconditioning (PC) to provide cardioprotection against myocardial infarction. An ischemia-reperfusion model of adult Wistar rats was used. Infarct size was expressed as a percentage of the area at risk under different treatment protocols. Octreotide PC (35 microg/Kg 20 minutes before ischemia-reperfusion) significantly decreased infarct size (18 +/- 4%) versus control (60 +/- 7%). The somatostatin receptor antagonist cyclo-somatostatin (0.5 mg/Kg) could blunt the above cardioprotection. Administration of either chelerythrine (a protein kinase C inhibitor, 2 mg/Kg) or genistein (a tyrosine kinase inhibitor, 5 mg/Kg) could also block octreotide PC (54 +/- 7% and 58 +/- 6%, respectively). Pretreatment with the mitochondrial ATP-sensitive potassium channel antagonist 5-hydroxydecanoic acid (5-HD) and the sarcolemmal ATP-sensitive potassium channel antagonist glibenclamide could abolish the effects of octreotide PC (54 +/- 6% and 52 +/- 6%). Chelerythrine, however, had no effect on octreotide PC. In conclusion, the present study demonstrates that octreotide can mimic ischemic PC to reduce infarct size. Acute effects of octreotide PC involve the activation of protein kinase C, tyrosine kinase C, and mitochondrial ATP-sensitive potassium channels, but not systemic IGF-I activation.
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PMID:Somatostatin analogue mimics acute ischemic preconditioning in a rat model of myocardial infarction. 1577 21

Adult male Wistar rats were subjected to 20 min of global cerebral ischemia and allowed to survive for 1, 2, 4, or 21 days. The brains were processed for immunocytochemistry and the hippocampal neuropeptide Y (NPY)-immunoreactive (-i) neurons were counted and compared to control values. In order to map out the subregional distribution of ischemic cell loss in the hippocampus, cells were also counted in hematoxylin-eosin (HE)-stained brain sections processed from additional ischemic rats after 21 days survival. Cell counts demonstrated a significant loss of hippocampal NPY-i somata 1-21 days after ischemia. The ischemic loss of somatal NPY-i was in the CAI stratum oriens, the CA1 stratum radiatum, and the CA3(ab) subfield not correlated to hippocampal cell loss. NPY-i fibers were found in all subfields of the hippocampus 1-21 days after ischemia. It is known that the majority (>50%) of hippocampal somatostatin-i (SS) neurons also costore NPY-i and the SS-i neurons in the CA1 and CA3(ab) regions of the hippocampus are preserved following an ischemic insult. The present results showed a 90% ischemic loss of CA1 and CA3 NPY-i somata. Based on these findings, it is concluded that ischemia selectively damaged NPY-i and not SS-i within some surviving hippocampal neurons that co-localized both peptides prior to the ischemia.
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PMID:Loss of somatal neuropeptide y immunoreactivity in the rat hippocampus following transient cerebral ischemia. 1581 97

In patients with colorectal cancer, low levels of colonic somatostatin, galanin and serotonin have been found. Based on these findings, the effects of triple treatment with octreotide (a somatostatin analogue), galanin and serotonin on colorectal cancer has been studied. Triple therapy was found to reduce the volume and weight of both rat and human colon carcinoma in xenografts, apparently by necrosis, but also by reducing proliferation and expression of epidermal growth factor of cancer cells, and also by inducing apoptosis. It has been suggested that tumour necrosis results from ischemia in the tumour caused by a reduction in the tumour blood flow, a consequence of reduced number of tumour-feeding blood vessels and by constricting of tumour feeding arterioles. The effects of treating rat colorectal cancer using single, double and triple therapy with octreotide, galanin and serotonin were studied. Of these substances, galanin alone achieved a significant reduction in tumour-feeding blood vessels. Single and double regimes had some effect, but were not nearly so successful as triple treatment. The optimum treatment dose of triple therapy lies between 40 and 80 microg/kg/day, smaller doses had no effect on the tumours at all, while larger doses had no additional effect. The optimal administration route is continuous i.p. infusion, for 14 days. Triple therapy gave no obvious side effects, and had equivalent anti-tumour and therapeutic efficacy as standard treatment with 5-fluorouracil/leucovorin. Although this treatment appears to be a promising option, clinical trials need be conducted to establish whether it can be beneficial in clinical use.
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PMID:Triple treatment with octreotide, galanin and serotonin is a promising therapy for colorectal cancer. 1597 62


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