Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Somatostatin receptors in the rat pituitary gland were characterized by binding analysis with a radioiodinated high affinity somatostatin analogue, 125I-Tyr1[D-Trp8]somatostatin. Receptor binding of this derivative reached equilibrium at 30 min and was maintained at a plateau for at least 60 min. Two L-Trp8- labeled somatostatin analogues. 125I-Tyr1- and [125I-Tyr11]somatostatin, displayed less stable and lower specific uptake and higher nonspecific binding. In contrast to the rapid degradation of the L-Trp8 ligands during binding assay, 125I-Tyr1]D-Trp8]somatostatin retained more than 80% of its binding activity after 90 min of incubation with pituitary particles. Pituitary particles bound 125I-Tyr1]D-Tyr8]somatostatin with high affinity (Ka = 8.6 +/- 1.2 X 10(9) M-1) and capacity of 54.4 +/- 2.6 fmol/mg. These binding sites showed specificity for the native peptide and its active analogues, and other peptide hormones, including angiotensin II, thyrotropin-releasing hormone, vasopressin, oxytocin, substance P, and gonadotropin-releasing hormone, did not inhibit tracer binding. A good correlation was observed between the binding affinities of several somatostatin analogues and their potencies as inhibitors of growth hormone release in rat pituitary cells. These findings emphasize the physiological importance of the pituitary somatostatin receptor in mediating the inhibitory action of the peptide on growth hormone release. The use of Tyr1[d-Trp8]somatostatin as a labeled ligand permits accurate determinations of the binding affinity and concentration of receptors for somatostatin in the normal pituitary gland and provides a basis for further studies of somatostatin receptor regulation and receptor-mediated cellular effects of the tetradecapeptide.
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PMID:Pituitary somatostatin receptors. Characterization by binding with a nondegradable peptide analogue. 612 Jan 62

Sandostatin, a synthetic octapeptide analog of a native hormone somatostatin, was labeled with a commonly available, inexpensive radionuclide, 99mTc, and evaluated for its suitability for in vivo imaging. Labeling was accomplished by reduction of the cystine bridge, which provided two sulfhydryl groups for chelation with 99mTc. The complex was examined for thermodynamic stability in vitro and in experimental animals. Receptor specificity of the complex was determined using rat brain cortex membrane rich in somatostatin receptors, and its tissue distribution was studied in nude mice bearing human prostate cancer. In these studies, 99mTc-labeled oxytocin, a nonspecific peptide with similar molecular weight, served as a control and 111In-DTPA-octreotide served as a standard. The labeling method was simple, did not require protecting and deprotecting functional groups and yields were high (ca. 70%). The in vitro and in vivo stability was excellent, and Kd values were in the nanomolar range, similar to those of 111In-DTPA-octreotide. At 24 hours post-injection, the tumor uptake for 99mTc-Sandostatin, expressed as percent of injected dose per gram (% ID/g), was higher, but the tumor/blood and tumor/muscle ratios were lower than those for 111In-DTPA-octreotide. This agent, with its improved target-to-nontarget ratios, should prove to be of value for imaging somatostatin receptor-positive tumors.
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PMID:Sandostatin labeled with 99mTc: in vitro stability, in vivo validity and comparison with 111In-DTPA-octreotide. 887 94

Neuropeptide W (NPW), which was originally isolated from the porcine hypothalamus, has been identified as the endogenous ligand for both the NPBWR1 (GPR7) and NPBWR2 (GPR8) receptors. These receptors, which belong to the orphan G protein-coupled receptor (GPCR) family, share a high sequence homology with the opioid and somatostatin receptor families. NPW and NPBWR1 are widely distributed in the rat central nervous system (CNS). While the intracerebroventricular (i.c.v.) injection of NPW elevates plasma corticosterone levels, the intravenous administration of NPW in conjunction with a corticotropin-releasing hormone (CRH) antagonist blocks NPW-induced corticosterone secretion. It has been reported that NPW is involved in regulating the hypothalamus-pituitary-adrenal cortex (HPA) axis and that i.c.v. administration of NPW decreases feeding behavior. The aim of the present study was to ascertain if NPW's role in feeding regulation is mediated (or not) through corticotropin-releasing hormone (CRH)-containing neurons. We found that NPW-containing axon terminals make synapses with CRH-immunoreactive cell bodies and dendritic processes in the hypothalamic paraventricular nucleus (PVN). The central infusion of NPW significantly induced c-Fos expression in CRH-immunoreactive neurons in the mouse PVN, but not in vasopressin- or oxytocin-immunoreactive neurons. To determine if NPW regulates feeding behavior through CRH neurons, the feeding behavior of mice was studied following the i.c.v. administration NPW in the presence or absence of pretreatment with a CRH antagonist. While NPW administration decreased feeding activity, the CRH antagonist inhibited this effect. These results strongly suggest that NPW regulates feeding behavior through CRH neurons in the mouse brain.
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PMID:Neuropeptide W-Induced Hypophagia is Mediated Through Corticotropin-Releasing Hormone-Containing Neurons. 2569 Nov 52