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)

The biosynthesis of oxytocin, vasopressin and their associated neurophysins were studied in the projection from the paraventricular nucleus of the hypothalamus to the spinal cord in individual freely-moving adult male rats. Neuropeptide biosynthesis was studied in vivo by the delivery of [35S]cysteine through stereotaxically implanted indwelling cannulae using an osmotic minipump delivery system. Following the appropriate chase times, the neural lobe and spinal cord segments T1-T4 and T12-L2 were removed from fresh tissue; in addition, the nucleus of the solitary tract was punched from frozen coronal sections. The radiolabeled peptides were purified from the tissue homogenates by sequential linear and exponential gradient elution from reverse-phase high performance liquid chromatography columns. This approach has allowed us to purify radiolabeled oxytocin and vasopressin from both the upper and lower spinal cord. However, the kinetics of oxytocin and vasopressin biosynthesis appeared to be remarkably different, as judged by their differential labeling with different pulse and chase times. Additionally, the use of different chase periods following the pulse of radiolabel has allowed us to determine that oxytocin reaches the spinal cord via the fast component of axonal transport (greater than 8 mm h-1). Using immunoprecipitation and purification by high performance liquid chromatography, we were also able to purify radiolabeled neurophysins from spinal cord tissue homogenates. These results lend further support to a role for oxytocin and vasopressin in the modulation of autonomic nervous system function and to the role of the paraventricular nucleus as an integration center for endocrine and autonomic function.
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PMID:In vivo biosynthesis and transport of oxytocin, vasopressin and neurophysin from the hypothalamus to the spinal cord. 242 Nov 98

An aminopeptidase from monkey (Macaca radiata) liver, inactivating oxytocin in vitro and located predominantly in the lysosomal and microsomal fractions, was purified by chromatography on Bio-Gel HTP, DEAE-Sephacel and nickel ion chelate gel and gel filtration on Sephacryl S300. Absence of binding to nickel ion chelate gel indicated the absence of exposed histidine and thiol residues on the enzyme. The enzyme appeared to be a high molecular weight (Mr 106,000) monomeric protein. It was sensitive to inhibition by metal chelators and was found to be a zinc metalloprotein by atomic absorption spectrophotometry. Divalent metal ions Ni2+ and Co2+, and sulphydryl activators glutathione and 2-mercaptoethanol had activating effects, while 4-chloro mercuribenzoate, amino acids with large hydrophobic side chains and L-cystine, beta-lactam antibiotic cloxacillin and peptidase inhibitor amastatin had inhibitory effects on the enzyme activity. The enzyme was most active against S-benzyl L-cysteine 4-nitroanilide substrate. The properties of the enzyme were distinct from those of the well-characterized alanine and leucine aminopeptidases (EC 3.4.11.2 and EC 3.4.11.1 respectively) of liver, and of primate placental cystine aminopeptidases (EC 3.4.11.3).
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PMID:A peptidase activity from primate liver that inactivates oxytocin in vitro: purification and partial characterization. 275 77

The effect of cysteamine injection on the in vivo incorporation of [35S]cysteine into somatostatin-14 (SRIF-14), SRIF-28, arginine vasopressin (AVP), and oxytocin (OXT) in rat hypothalamus was studied. [35S]Cysteine was injected into the third ventricle 1 h, 4 h, or 1 week after cysteamine (300 mg/kg, sc) injection; animals were killed 4 h later. The drug was found to substantially reduce immunoreactive SRIF levels, but not OXT or AVP, 4 h after its injection. Cysteamine also caused large reductions in label incorporation into SRIF-14, SRIF-28, and OXT 1 and 4 h after drug injection. However, [35S]cysteine incorporation into AVP was increased substantially at these time points, while that into acid-precipitable protein was normal. One week after cysteamine injection, label incorporation into all hypothalamic peptides was normal. Cysteine specific activity was also measured after [35S]cysteine injection and was found to be similar in treatment and control groups. The results suggest that cysteamine inhibits the syntheses of SRIF-14, SRIF-28, and OXT and stimulates that of AVP.
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PMID:Effects of cysteamine administration on the in vivo incorporation of [35S]cysteine into somatostatin-14, somatostatin-28, arginine vasopressin, and oxytocin in rat hypothalamus. 287 17

The rates of incorporation of [35S]cysteine into arginine vasopressin (AVP) and oxytocin (OXT) were studied concurrently in hypothalami from intact and hypophysectomized male rats. After label injection into the third ventricle, rats were killed 0.5, 1, 2, 4, or 8 h later. The hypothalamic peptides were quantitated by specific RIA and separated by HPLC to allow quantitation of label incorporation into each peptide. In intact rats, labeling of both OXT and AVP rose rapidly to peak at 2 h; thereafter, radioactivity in both peptides declined slowly to 8 h. In hypophysectomized rats, labeling of AVP fell below that in intact animals at all time points. Labeling of OXT was somewhat below normal 2 h after label injection, but considerably above normal at 4 and 8 h. For comparison, label incorporation into somatostatin-14 (SRIF-14) and somatostatin-28 (SRIF-28) was also studied in the same animals. In intact rats, labeling of both SRIF peptides rose slowly to maximal values at 8 h. In hypophysectomized animals, labeling of each peptide was reduced substantially at all times tested. Endogenous cysteine specific activity and protein specific activity did not differ between intact and hypophysectomized animals. Immunoreactive levels of AVP and OXT in the hypothalamus were unaffected by hypophysectomy, though total SRIF-like immunoreactivity was depressed. Together these results suggest that hypothalamic neurons synthesize OXT and AVP at rates much faster than those for the SRIF peptides, and that hypophysectomy has differential effects on the syntheses of cysteine-containing peptides in the hypothalamus. Specifically, the syntheses of SRIF-14 and SRIF-28 appear to be sizeably reduced in hypophysectomized rats, while that of AVP only modestly diminished. OXT synthesis may be increased.
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PMID:In vivo biosynthesis of arginine vasopressin and oxytocin in hypothalami from intact and hypophysectomized rats. 288 2

Preprovasopressin-neurophysin II (prepro-AVP-Np), the precursor of the cyclic, amidated nonapeptide, arginine vasopressin (AVP), is present in the central and peripheral nervous systems, adrenal glands, and gonads of rats. To study cell-specific processing of prepro-AVP-Np, a fusion gene consisting of the heavy metal-inducible promoter of the mouse metallothionein I gene and the rat prepro-AVP-Np gene was introduced by cellular transfection into several defined cell phenotypes: a fibroblast line (BHK), a pituitary growth hormone and prolactin-producing cell line (GH4), a pituitary cell line that produces several amidated peptides (AtT-20), and an insulin-producing pancreatic islet line (RIN- 1046-38). Clonal cell lines were isolated and prepro-AVP-Np-specific transcripts were detected by Northern blot hybridization analyses. Fibroblast BHK and pituitary GH4 cells transfected with the fusion gene synthesized a polypeptide (Mr = 18,000) characteristic of the glycosylated precursor, pro-AVP-Np; in metal -treated cells, this protein was the major secreted cysteine-labeled polypeptide. Extracts of RIN-1046-38 and AtT-20 cells transfected with the fusion gene contained predominantly processed neurophysin and amidated arginine vasopressin, whereas extracts of BHK and GH4 cells contained mainly precursors of AVP and neurophysin. These observations indicate that the pathways involving specific post-translational processing of pro-AVP-Np are more efficiently utilized in the prohormone-producing AtT-20 and RIN-1046-38 cells than in GH4 and BHK cells that do not synthesize any recognized prohormones.
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PMID:Provasopressin-neurophysin II processing is cell-specific in heterologous cell lines expressing a metallothionein-vasopressin fusion gene. 365 60

A tissue culture model was established for the study of hypothalamic peptide synthesis and secretion. Microdissected explants of the paraventricular and supraoptic regions from Sprague-Dawley rats (neonates or young rats) were maintained in culture for up to 3 weeks. Studies were performed to evaluate vasopressin and oxytocin content (medium and tissue levels), immunocytochemical localization, and biosynthetic activity. Immunocytochemical staining for oxytocin, neurophysin, and neuron-specific enolase showed positive neurons in both the paraventricular and supraoptic cultures. In many cases, the neurons were large (30-40 microns) and bipolar, resembling the classic magnocellular neuron. Measurement of tissue and medium content showed the continued presence of vasopressin and oxytocin in the cultured explants. Even after 3 weeks, there were significant amounts of vasopressin present. Biosynthesis was evaluated by determining the incorporation of 35S-labeled cystine or cysteine into proteins and peptides. The medium and tissue extracts were separated by reverse-phase high-performance liquid chromatography. Results showed that most of the labeled peptides were released into the medium rather than stored. There were two labeled peaks in the medium, which chromatographically resembled native vasopressin and oxytocin. Treatment with a protein synthesis inhibitor, either puromycin or cycloheximide, resulted in a decrease in labeled peptides. A comparison of 35S-labeled cystine and cysteine showed that the latter was the label of choice, with significantly greater incorporation.
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PMID:Biochemical and immunochemical studies of supraoptic and paraventricular cultures. 372 56

Lesions of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) have been shown to disrupt body fluid homeostasis. The acute post-lesion phase in rats is characterized by adipsia, the lack of an appropriate antidiuretic response, and plasma vasopressin levels which do not rise. Electron micrographs of the supraoptic nucleus and neural lobe of lesioned adipsic rats suggest no stimulation of biosynthetic activity, and large stores of neurosecretory material in the axon terminals. To directly investigate the status of these neurons, we determined neural lobe vasopressin and oxytocin content and the incorporation of [35S]cysteine into hypothalamic proteins in rats with sham-lesions or lesions of the AV3V after 3 days of adipsia or water deprivation, and in water replete sham-lesioned rats. The results demonstrate that adipsic rats with AV3V lesions have neural lobe vasopressin and oxytocin content equivalent to water-replete sham-lesioned rats. Neural lobe vasopressin and oxytocin levels of water-deprived sham-lesioned rats were significantly below those of all other groups. In addition, this group had a radioactivity incorporation rate into hypothalamic proteins which was two-fold greater than either of the other groups. The results indicate that 3-day adipsic AV3V-lesioned rats do not increase neurohypophyseal hormone release or biosynthesis as do 3-day water-deprived sham-lesioned rats. The periventricular tissue of the AV3V would therefore appear to be crucial in providing information to the hypothalamo-neurohypophyseal neurons on body fluid homeostasis.
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PMID:Neurohypophyseal hormone release and biosynthesis in rats with lesions of the anteroventral third ventricle (AV3V) region. 374 94

Neurosecretory granules from the rat and bovine neurohypophysis were isolated and some of their biochemical and biophysical properties studied. Neurosecretory granules (NSG) from rat neurohypophysis were labeled, in vivo, with [35S]cysteine and isolated on isoosmotic gradients. Whereas 1 day after labeling most of the radioactivity was found in the lower part of the gradient, 35 days later the isotope was also located in the lighter NSG-containing fraction. Different analytical procedures showed that the lighter fraction, both in bovine and rat NSG, contain more subpopulations of neurophysin-like material than the heavier fraction. The first material to be released during stimulation of secretion, in vivo or in vitro, is mobilized from the heavy NSG. Isolation of rat NSG, at different times during and after dehydration of the animals, reveals that the newly synthesized material is found in the heavy NSG-containing fraction. Furthermore, the results indicate that the newly synthesized NSG are more resistant to lysis than the lighter granules. The results are discussed in relation to the maturation and degradation processes of the granule content and to the functional state of the NSG.
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PMID:Characterization of newly formed and aged granules in the neurohypophysis. 376 Aug 74

Tocinoic acid analogs with penicillamine in place of one or both of the cysteine residues have been studied and [1-beta-mercaptopropionic acid, 6-penicillamine] tocinoic acid (dPen6TA) and [1-beta,beta-dimethyl-beta-mercaptopropionic acid, 6-penicillamine] tocinoic acid (dPen1Pen6TA) have been synthesized in solution. Biological activities of these 2 compounds and those of the previously synthesized [1-beta,beta-dimethyl-beta-mercaptopropionic acid] tocinoic acid (dPen1TA) have been assayed. It was found that dPen1TA and dPen1Pen6TA, both of which have a beta,beta-dimethyl-beta-mercaptopropionic acid in position 1, are strong inhibitors of the uterine activity of oxytocin in vitro (without Mg2+) with pA2 values of 7.1 and 7.8, respectively, whereas dPen6TA with penicillamine in position 6 is a mild agonist.
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PMID:Desaminopenicillamine tocinoic acid derivatives--inhibitors of oxytocin. 377 Nov

Twenty-four hours after the injection of [35S]cysteine near either the rat paraventricular nuclei or the supraoptic nuclei, the [35S]neurophysin-like proteins of the brain stem were extracted, immunoprecipitated with anti-bovine neurophysins antibodies and analyzed. They consisted essentially of species behaving as neurophysin on sodium dodecyl sulfate--polyacrylamide gel electrophoresis. There was a very low percentage of neurophysins precursors which could be characterized in the paraventricular nuclei. In the rats pretreated by colchicine, the [35S]neurophysins were not detected in the brain stem, while they appeared in the paraventricular nuclei indicating that the precursors have been processed and the transport inhibited. These results suggest that: (i) both the biosynthetic and transport events in the hypothalamo-brain stem pathway are comparable to those occurring in the hypothalamo-neurohypophyseal tract; (ii) this pathway originates both from the supraoptic and paraventricular nuclei. Moreover, they indicate that processing is essentially complete in the hypothalamus of colchicine-pretreated animals. This provides further support to a model associating enzymes with both the endoplasmic reticulum membranes and the derived corresponding secretory vesicles.
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PMID:Hypothalamic biosynthesis and transport of neurophysins and their precursors to the rat brain stem. 399 5


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