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

The reaction products of plasma enzyme degradation of TRH were identified by thin layer chromatography. The enzyme in normal rat plasma yields proline and pGlu-His as major reaction products. High concentrations of proline decrease peptide cleavage, resulting in greater amounts of acid TRH. The apparent Km of the enzyme is 4.1 X 10(-6) M. LHRH and neurotensin are competitive inhibitors with Ki of 5 X 10(-6) M and 1.5 X 10(-5) M, respectively. Somatostatin, MIF, oxytocin, arg-vasopressin, arg-vasotocin, neurophysin II and glucagon do not compete; and pGlu-His-Pro-OH, Glu-His-Pro-OH, pGlu-His, His-Pro-NH2, and Pro-NH2 do not affect enzyme activity. These data suggest that the substrated requires pGlu and a terminal or internal amide to complex with the enzyme. The enzyme is markedly inhibited by Cu++, Bal, benzamadine, p-(chloromercuri)-benzoic acid, moderately affected by EDTA and puromycin, and unaffected by mercaptoethanol. TSH does not affect enzyme activity while LH inhibits it moderately at high concentrations (300-600 pg/ml).
 ...
PMID:Characteristics of the plasma TRH-degrading enzyme. 81 19

Immunoperoxidase technique and light microscopy have been used to localize neurosecretory systems for vasopressin, oxytocin and related neurophysins (neurohypophysial peptides)) and gonadotropin-releasing hormone (Gn-RH) in the rhesus monkey brain. All the neurohypophysial peptides were found in the magnocellular nuclei (suproptic and paraventricular) of the hypothalamus and in their projections to the posterior pituitary gland, the zona externa of the median eminence and the organum vasculosum of the lamina terminalis (OVLT). Gn-RH was found in smaller cell bodies which were widely scattered in the hypothalamus. Some of these were found in the media-basal hypothalamus in the infundibular nucleus and lateral and dorsal to it, while others were found in dorsal hypothalamus. Numerous cells were also located in the preoptic area close to the OLVT. Gn-RH-containing fibers projected to the OVLT and the zona externa of the median eminence. The two neurosecretory systems studied have two common features: magnocellular perikarya containing the neurohypophysial peptides and smaller elements containing Gn-RH are found near and appear to terminate around the fine vessels of the OVLT. In addition, cells of both systems send fibers to the hypophysial portal capillary system in the zona externa of the median eminence. Many more vasopressin-than oxytocin-containing fibers end in the entire expanse of the zona externa, where they are mainly concentrated in the anterior and middle parts, while Gn-RH fibers project to all portions.
 ...
PMID:Organization of the hypothalamic-pituitary system: current concepts from immunohistochemical studies. 82 99

The effect of toluene on the hypothalamic hormone-secreting neurons and neurotransmitter-containing fibers in the rat was investigated by immunohistochemical methods. Multiple intraperitoneal injections of toluene (totally 7.5 ml) led to significant decreases of the neuronal numbers of vasopressin, oxytocin and neuropeptide Y in the preoptic and hypothalamic areas. The densities of vasopressin, oxytocin, norepinephrine and neuropeptide Y immunoreactive fibers of the toluene dose group decreased markedly in the median eminence. In contrast, LHRH neurons remained unchanged.
 ...
PMID:Effects of toluene on the morphology of neuropeptide secretory neurons of the rat hypothalamus. 130 69

Renal cell carcinoma has been reported to contain estrogen and progesterone receptors. Thus, it has been suggested that these tumors are hormone dependent in a similar manner described for the breast and prostate cancers. It has been recently shown that mammary and prostate tumor cells contain gonadotropin-releasing hormone (GnRH) receptors and are growth inhibited directly by GnRH antagonists. In this study we examined for the presence of GnRH, estrogen and progesterone receptors in normal and malignant renal tissues. Estrogen receptors were found both in the normal and malignant kidney while progesterone receptors were present only in the normal tissue. Specific binding of [125I]buserelin, a GnRH agonist, was evident in renal carcinoma and in normal kidney and was displaced with equal efficiency by unlabeled buserelin and by D-Trp6-GnRH, but not by unrelated peptides such as thyrotropin releasing hormone and oxytocin. The non-linear scatchard curve obtained for buserelin binding, suggests the presence of at least two binding sites, one with high affinity in the nanomolar range and another in the micromolar range.
 ...
PMID:Gonadotropin-releasing hormone specific binding sites in normal and malignant renal tissue. 133 44

Physiological role and importance of calcium ion has been investigated based on the study of the mechanism of muscle contraction. Furthermore, calcium ion has been proved to have a wide variety of biological roles in hormonal secretion, cell proliferation and reproduction as well as in muscle contraction. In this lecture, I would like to show a method to measure intracellular calcium ion concentrations ([Ca2+]i) and to give a general information about the roles of calcium ion to induce various cell activities. Then I would like to talk about the changes in intracellular calcium concentration ([Ca2+]i) and their meaning in the field of reproductive physiology including uterine muscle contraction, pituitary LH secretion, and fertilization. 1) Uterine muscle contraction and calcium ion The function of calcium ion is most intensively investigated in muscle contraction. We show [Ca2+]i increase in cultured myometrial cells. This increase is inhibited by omission of extracellular calcium or addition of calcium channel blockers. These results support usefulness of Ca2+ channel blockers in treating threatened premature delivery. We also report the action of MgSO4 as an inhibitory agent of [Ca2+]i increase stimulated by oxytocin. 2) Pituitary gonadotropin secretion and calcium ion Pituitary LH secretion is regulated by gonadotropin releasing hormone (GnRH). GnRH induces rapid increases and then sustained releases of LH secretion. By the omission of extracellular calcium, or by addition of Ca2+ channel blockers, the sustained phase of LH secretion is abolished. GnRH also increase [Ca2+]i in a very similar manner to that of LH secretion. The [Ca2+]i increase is essential in LH secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[Roles of calcium ion in reproductive physiology]. 140 28

Recently, we have described a chorionic peptidase (C-ase-1) which inactivates gonadotropin releasing hormone (GnRH), oxytocin, angiotensin II and thyrotropin releasing hormone. Since all these hormones contain a proline residue, we proposed that C-ase-1 may act as a post-proline peptidase. Using HPLC and amino acid analyses, we have defined the products which resulted from enzymatic inactivation of GnRH by C-ase-1. The N-terminal nonapeptide of GnRH was isolated by HPLC and confirmed by amino acid composition analyses. Thus, it was demonstrated that C-ase-1 acts as a post-proline peptidase when inactivating GnRH, yielding the nonapeptide, i.e., des-Gly10-NH2-GnRH, and Gly-NH2. The levels of intrauterine GnRH, angiotensin II, oxytocin and thyrotropin releasing hormone may be affected and integrated by this enzyme. Thus, C-ase-1 may play an important role in the regulation of the paracrine and endocrine function during pregnancy.
 ...
PMID:Chorionic peptidase inactivates GnRH as a post-proline peptidase. 150 38

Specific low-affinity high-capacity binding sites for gonadotropin-releasing hormone (GnRH) have recently been discovered in human breast and ovarian carcinomata. We checked whether similar binding sites are present in human endometrial cancer. Plasma membrane preparations were incubated with [125I,D-Ala6-desGly10]-GnRH-ethylamide in the presence or absence of unlabelled GnRH agonists or other peptides. GnRH-binding could be demonstrated in all 12 tumor samples tested. The mathematical analysis of the binding data was consistent with a single class of low affinity (Ka = (0.8-1.4) x 10(5) M-1) and high-capacity (Bmax = (134-142) x 10(-12) M/mg membrane protein) binding sites. Native GnRH had a similar affinity to the binding sites as the GnRH agonist used. Other peptides such as oxytocin, somatostatin and thyrotropin-releasing hormone did not crossreact with the binding sites. A photolabelled derivative of [D-Lys6]-GnRH was prepared with the bifunctional photolabile reagent (4-azidobenzyl)-N-hydroxysuccinimide. Photoaffinity labelling of endometrial carcinoma membranes and subsequent sodium dodecyl sulfate electrophoresis in 10% polyacrylamide gel revealed the presence of a single molecular mass component of 62 +/- 1.9 kDa. The appearance of this photolabelled binding site could be largely suppressed by the addition of unlabelled GnRH-agonist (10(-4) M) and thus represents the specific binding site for GnRH in endometrial cancer.
 ...
PMID:Specific low affinity binding sites for gonadotropin-releasing hormone in human endometrial carcinomata. 165 55

A variety of neuroendocrine cells survive and express specific neuropeptide genes for long periods of time in slice explant cultures in the presence of serum. However, before use of these slice explant cultures as experimental models for physiological and pharmacological studies on the regulation of neuropeptide gene expression, it is first necessary to evaluate their characteristics in defined (e.g. serum free) media and to control for the spontaneous electrical and synaptic activity of neurons in these cultures. In this study, brain slices from postnatal day 4 rats were cultured in serum-containing media (SCM) for 12 days to allow thinning, and then maintained in a serum-free, defined media (SFM) for 6 days. Culture slices transferred to SFM appeared healthy and numerous neuroendocrine neurons containing messenger RNA (mRNA) encoding for LHRH and magnocellular neurons containing mRNA encoding for oxytocin (OT) were detected using in situ hybridization histochemistry (ISHH). Each of these neuronal subtypes robustly produced their appropriate gene products as determined by immunocytochemical analysis. Abundant magnocellular OT neurons were found in cultures grown in either SCM or SFM. In contrast, magnocellular vasopressin (VP) neurons were rarely detected under these conditions. Inhibition of spontaneous electrical and synaptic activity in these slice explant cultures was effectively achieved by incubation for the last 2.5 days of culture in the presence of tetrodotoxin (TTX; 10(-6) M). Densitometric single cell analyses after ISHH was performed on both LHRH and OT cells. Comparisons of the density values (corresponding to mRNA levels), from these slice explants, found that: (1) cellular LHRH mRNA levels decreased in the absence of serum, whereas cellular OT mRNA levels did not significantly change under these conditions; (2) the presence of TTX in the media resulted in an overall decrease in cellular LHRH mRNA values in both SCM and SFM, and (3) the OT neurons in these slice cultures appear to be composed of a heterogeneous population, with one cell subtype responding to TTX with an increase in cellular OT mRNA levels. These data show that factors in serum and spontaneous electrical activity can differentially influence mRNA levels of LHRH cells and magnocellular OT neurons in culture.
 ...
PMID:Maintenance of LHRH and oxytocin neurons in slice explants cultured in serum-free media: effects of tetrodotoxin on gene expression. 175 75

Effect of vasopressin, oxytocin and LHRH (10 and 20 pg/ml medium) on the proliferation and metabolism of cultured rat bone marrow stromal cells was investigated by methyl-3H-thymidine incorporation, cytochemistry and estimation of enzyme activities. Vasopressin did not change of the activity of tetrahydrofolate dehydrogenase (4HFDH), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD) and the level of reduced glutathione (GSH). However, the higher concentration of vasopressin significantly lowered the activity of acetylcholinesterase (AchE). As compared with the control cultures, stromal cells grown in the presence of oxytocin showed higher (at lower hormone concentration) and lower (at higher concentration) LDH activity as well as lower G6PD activity (only at higher concentration), while the activity of AchE and the level of GSH was not changed. LHRH significantly increased G6PD and AchE activity and decreased LDH activity in the cultured cells. As revealed by cytochemistry, LHRH specifically enhanced 4HFDH activity in reticular cells.
 ...
PMID:Effect of vasopressin, oxytocin and LHRH on the proliferation and metabolism of rat bone marrow stromal cells in culture. 176 8

Changes in the structure and function of five neuropeptide families during evolution are considered. The families of gonadotropin-releasing hormone (GnRH), corticotropin-releasing factor (CRF), growth hormone-releasing hormone (GH-RH), somatostatin (SS), and vasopressin/oxytocin (VP/Oxy) are used as models to illustrate the importance of a phylogenetic approach in understanding neuropeptide structure/activity relationships, precursors, processing, gene duplication, novel locations and functions, and gene-associated peptides.
 ...
PMID:Neuropeptide families: an evolutionary perspective. 197 5


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