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)

Preliminary studies in rats (COSMOS 1887) suggested that levels of posterior pituitary hormones were reduced by exposure to spaceflight. To confirm these preliminary findings, we obtained pituitary tissue from rats flown for 14 days on COSMOS 2044. Posterior pituitary content of oxytocin (OT) and vasopressin (VP) were measured in these tissues as well as those from ground-based controls. The synchronous control group had feeding and lighting schedules synchronized to those in the spacecraft and were maintained in flight-type cages. Another group was housed in vivarium cages; a third group was tail suspended (T), a method used to stimulate microgravity. Flight rats showed an average reduction of 27% (P less than 0.05) in pituitary OT and VP compared with the three control groups. When hormone content was expressed in terms of pituitary protein (micrograms hormone/mg protein), the average decrease in OT and VP for the flight animals ranged from 20 to 33% (P less than 0.05) compared with the various control groups. Reduced levels of pituitary OT and VP were similar to preliminary measurements from the COSMOS 1887 mission and appear to result from exposure to spaceflight. These data suggest that changes in the rate of hormone secretion or synthesis may have occurred during exposure to microgravity.
 ...
PMID:Pituitary oxytocin and vasopressin content of rats flown on COSMOS 2044. 152 46

Our laboratory has provided substantial evidence for the presence of PRL-releasing factor (PRF) in the posterior pituitary. The objectives of this study were 1) to determine the distribution of PRF activity between the neural and intermediate lobes, and 2) to assess the PRF activity of cultured posterior pituitary cells. Posterior pituitaries from adult male rats were dispersed with trypsin and cultured for 1-7 days. Cultured cells or intact posterior pituitaries were extracted with acid and lyophilized. PRF activity was determined by the ability of reconstituted extracts to increase PRL release from cultured anterior pituitary cells. Upon dissection of the posterior pituitary, PRF activity was primarily present in the intermediate lobe. There was minimal contamination between the two lobes, as indicated by the localization of 90% of the total oxytocin in the neural lobe and 95% of alpha MSH in the intermediate lobe. Extracts from intact posterior pituitaries and posterior pituitary cells cultured for 4 days stimulated PRL secretion in a similar dose-dependent manner. Cultured liver and cerebral cortex cells had very low PRF activity. Both oxytocin and dopamine, two neuronal markers, were reduced to less than 5% of their original values within 1 week of cell culture. There was also a significant reduction in the cell content of alpha MSH. On the other hand, PRF activity was relatively stable during culture. Incubation of posterior pituitary cells for 4 days with either cycloheximide or PRL caused a 55-60% reduction of the PRF activity of the cells. We conclude the following. 1) PRF is localized, almost exclusively, in the intermediate lobe of the pituitary. 2) PRF activity is present within nonneuronal cells, either melanotrophs or a small subpopulation of nonopioid-producing cells. 3) PRF is tissue specific, and its presence in cultured posterior pituitary cells depends at least in part on de novo synthesis. 4) The synthesis and/or release of PRF may be subjected to short loop negative feedback regulation by PRL.
 ...
PMID:Prolactin-releasing factor: cellular origin in the intermediate lobe of the pituitary. 211 57

We have recently reported that the posterior pituitary contains PRL-releasing factor (PRF), a small (less than 5000 mol wt) peptide which induces a rapid, hormone-specific, and concentration-dependent stimulation of PRL secretion. Although the identity of posterior pituitary PRF is yet unknown, it is distinct from known PRL secretagogues. Recently, the vasopressin-associated glycopeptide (VAG), which is concentrated in the posterior pituitary, was suggested as a PRF. To investigate whether VAG functions as a PRF, we used Brattleboro rats, which are deficient in arginine vasopressin (AVP), AVP-associated neurophysin, and VAG. Homozygous (DI) and heterozygous (HZ) lactating Brattleboro rats were used. The water consumption of pregnant DI rats (greater than 300 ml/day) was 6-fold higher than that of HZ rats. To correct their water imbalance, DI rats were implanted with osmotic minipumps containing the vasopressin analog 1-desamino-8-D-arginine vasopressin. On days 7-8 of lactation, pups were separated for 6 h, and blood was collected from the dams via a jugular cannula. Upon introduction of the pups, plasma PRL levels increased 100-fold in both DI and HZ rats and remained elevated for the duration of suckling. The suckling-induced rises in plasma oxytocin in DI and HZ rats were also superimposable. The weight gains of the pups of DI and HZ mothers were similar. PRF activity was determined using perifused anterior pituitary cells. Posterior pituitaries from DI and HZ rats contained equivalent amounts of PRF activity. Moreover, purified rat VAG (1.5 and 6.0 micrograms) failed to stimulate PRL release from pituitary cells. The posterior pituitary content of immunoreactive AVP was 2500-fold higher in HZ rats, but the contents of dopamine and oxytocin were similar. It is concluded that VAG neither mediates the suckling-induced rise of plasma PRL, nor stimulates PRL secretion from perifused anterior pituitary cells. Furthermore, posterior pituitaries from DI and HZ rats contain equivalent amounts of PRF activity. Collectively, these data indicate that VAG is not the posterior pituitary PRF.
 ...
PMID:The vasopressin-associated glycopeptide is not a prolactin-releasing factor: studies with lactating Brattleboro rats. 250 Mar 28

We have recently shown that the posterior pituitary (neurointermediate lobe) contains a potent prolactin (PRL)-releasing factor (PRF) which is distinct from known PRL secretagogues. Posterior pituitary PRF appears to be a small peptide of an unknown cellular origin. Using pituitary stalk-sectioned (SS) male rats, the objectives of this study were: (1) to determine if PRF is transported from the hypothalamus or is synthesized within the pituitary gland, and (2) to compare changes in PRF activity with alterations in the posterior pituitary content of beta-endorphin (beta-END), oxytocin (OXY), and dopamine (DA). One or two weeks following pituitary SS or sham surgery (SHAM), acid extracts of the posterior pituitary and medial basal hypothalamus (MBH) were analyzed for their hormone content. PRF activity was assessed by determining the stimulation of PRL secretion from perifused anterior pituitary cells, DA was measured by HPLC, and OXY and beta-END levels were determined by RIAs. OXY and DA concentrations in the posterior pituitary were reduced more than 95% at both 1 and 2 weeks after SS. PRF activity in the posterior pituitary was significantly reduced by 75 and 90%, 1 and 2 weeks after SS, respectively. In contrast, beta-END levels in the posterior pituitary at these times increased 20 and 60%, as compared to SHAM rats. Unlike the posterior pituitary, OXY levels in the MBH increased 123% 1 week following SS, and 1,260% at 2 weeks. These increases may reflect the accumulation of OXY-containing secretory vesicles in the severed nerves. DA concentrations in the MBH showed a biphasic pattern. DA levels were initially decreased by 70%, and then increased, but remained 30% below SHAM levels. The reason for these alterations in DA levels is not clear.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Differential effects of pituitary stalk-section on posterior pituitary and hypothalamic contents of prolactin-releasing factor, oxytocin, dopamine and beta-endorphin. 297 37

We previously reported that the rat posterior pituitary contains a potent PRL-releasing factor (PRF) which is distinct from oxytocin (OT), TRH, and angiotensin II (AII). The objectives of this study were 1) to examine whether posterior pituitary extracts stimulate PRL release in the presence of dopamine (DA), 2) to determine the chemical nature of PRF, and 3) to estimate its mol wt. Perifused anterior pituitary cells were used to assess PRF activity. Posterior pituitaries and medial basal hypothalamus (MBH) fragments were extracted with perchloric acid and lyophilized. Subsequent to various treatments, samples were reconstituted in the perifusion medium and introduced to the cells in short pulses. Fractions were collected and analyzed for hormone content by RIA. During a constant infusion of DA (50 nM), PRL secretion was inhibited by 75%, yet the posterior pituitary extract retained its ability to rapidly stimulate PRL release. Studies using proteolytic enzymes showed that posterior pituitary PRF was resistant to inactivation by trypsin, whereas the PRF activity of AII was abolished. Both chymotrypsin and proline-specific endopeptidase significantly reduced the PRF activity in the posterior pituitary. The PRL-releasing activity of TRH was not affected by chymotrypsin. Immunoreactive vasoactive intestinal polypeptide was undetectable in posterior pituitary extracts. Oxidation of posterior pituitary extracts with performic acid caused only a modest reduction of their PRF activity, while the ability of OT to stimulate PRL release as well as immunoreactive OT was abolished. Studies using ultrafiltration membranes showed that the PRF activity in the posterior pituitary was less than 5,000 mol wt. Furthermore, posterior pituitary PRF partitioned in nearly equal amounts across 1K membranes, as did AII and OT. In contrast, about 80% of the PRF activity in the MBH and all of the synthetic TRH passed through the 1K membranes. We conclude that 1) posterior pituitary PRF can stimulate PRL secretion from perifused anterior pituitary cells in the presence of physiological concentrations of DA; 2) PRF is a small peptide(s) of less than 5,000, and perhaps closer to 1,000, mol wt; 3) PRF is resistant to inactivation by trypsin and to oxidation by performic acid, but is hydrolyzed by both chymotrypsin and proline-specific endopeptidase; and 4) these data further distinguish posterior pituitary PRF from known PRL secretagogues.
 ...
PMID:Characterization of prolactin-releasing factor in the rat posterior pituitary. 313 Nov 18

Posterior pituitary injection is an extract prepared from the dried posterior lobe of the pituitary gland from domestic animals containing two octapeptide hormones, oxytocin and vasopressin. Posterior pituitary injection carries an approved therapeutic indication as an adjunct measure for achieving surgical hemostasis. We report a case of cerebral edema and death attributed to water intoxication in a child who had received a large volume of free water concurrent with posterior pituitary injection to control bleeding after tonsillectomy and adenoidectomy.
 ...
PMID:Water intoxication and death associated with the use of posterior pituitary injection for surgical hemostasis. 372 May 41

Seven mouse monoclonal antibodies (IgGs) were produced against rat neurophysins (NPs). Three were specifically directed against vasopressin-associated NP (NP-AVP), and four were specific for oxytocin-associated NP (NP-OT). These specificities were observed in liquid phase assays, immunoblot, and immunoprecipitation experiments. Homozygous Brattleboro rat tissues and extracts, which do not contain vasopressin or NP-AVP, did not react with the anti-NP-AVP antibodies but reacted with high affinity to the anti-NP-OT antibodies. In immunoprecipitation assays the antibodies brought down the appropriate NPs as well as their precursor molecules synthesized in vivo with no detectable cross-reactivity. In solid phase assays where the antigens were presented in a different manner, there was a significant cross-reactivity of the anti-NP-AVP antibodies with NP-OT. The extent of this cross-reactivity in solid phase correlated with the cross-reactivities of the antibodies observed in immunocytochemical studies. These solid phase (and immunocytochemical) data demonstrated that liquid phase specificities and absorption controls of antibodies are inadequate to assess their immunocytochemical (solid phase) specificities. Posterior pituitary extracts from the mouse and frog, as well as purified NPs from the rat, cow, and human were studied for their cross-reactivities to two of the antibodies, PS 36 and PS 45. In liquid phase assays the anti-rat NP-OT antibody, PS 36, reacted only with rat and mouse NPs and did not cross-react with NPs from any of the other species. In contrast, the anti-rat NP-AVP antibody, PS 45, was cross-reactive across species lines including an NP-like antigen extracted from frog posterior pituitaries. Immunoblot staining with these antibodies showed heterogeneity of NP-AVP and NP-OT in the rat posterior pituitary. Analysis of the epitopes for PS 36 and PS 45 indicated the antigenic determinants were located near amino acid positions 80 to 81 in NP-OT and 75 to 86 in NP-AVP, respectively.
 ...
PMID:Neurophysin in the hypothalamo-neurohypophysial system. I. Production and characterization of monoclonal antibodies. 388 Aug 13

Posterior pituitary lobes from young pigs were fractionated by differential and sucrose-density-gradient centrifugation. The distributions of oxytocin and [8-lysine]-vasopressin were measured by bioassay and the distributions of neurophysin-I and -II by radioimmunoassays specific for each of these two proteins. Most of the hormone and neurophysin applied to the density gradient was localized in particles with the density expected of neurosecretory granules. However, the neurosecretory granules were separated into two bands (D and E). A close statistical correlation between the distributions of [8-lysine]-vasopressin and neurophysin-I, and of oxytocin and neurophysin-II on the gradients, suggested that in vivo porcine neurophysin-I binds [8-lysine]-vasopressin within one population of granules and porcine neurophysin-II binds oxytocin within another type of granule. However, there was no significant separation of oxytocin and vasopressin in fractions D and E. The molar ratios of hormones and neurophysins indicated that there was insufficient of either neurophysin to bind the [8-lysine]-vasopressin in the granule fractions or in the whole gland. Polyacrylamide-gel electrophoresis showed that only bands corresponding in mobility to porcine neurophysins-I, -II and -III were present in large amounts in the whole gland and in the granule fractions. The component with the mobility of neurophysin-III was, however, relatively enriched in whole young glands and granule fractions compared with adult gland extracts. It is suggested that the vasopressin that cannot be assigned to neurophysin-I may occur in (a) vesicles containing vasopressin but no neurophysin, (b) vesicles containing vasopressin and a protein that cannot be quantified by the radioimmunoassays used, such as porcine neurophysin-III, or (c) normal vasopressin-neurophysin granules which have accumulated extra vasopressin. Band E of the gradient was rich in adenosine triphosphatase activity, whereas band D possessed very little of this enzyme.
 ...
PMID:Subcellular organization of neurophysins, oxytocin, (8-lysine)-vasopressin and adenosine triphosphatase in porcine posterior pituitary lobes. 426 6

Porcine neurophysin proteins as well as oxytocin and lys-vasopressin were extracted from fresh (immediately after death) and stored (10, 20 and 60 min, 6, 12 and 24 hours) pituitary posterior lobes. Analyses were performed by high performance liquid chromatography (HPLC). In fresh tissue all forms of neurophysin proteins were present, the pattern of distribution of the neurophysins, oxytocin and lys-vasopressin did not change during the period of storage while other unknown peaks showed degradation. Posterior pituitary glands can be used for the preparation of neurophysin proteins, oxytocin and lys-vasopressin within 24 hours after death.
 ...
PMID:Postmortal degradation of neuropeptides in the neurohypophysis. 662 29

A cell-by-cell analysis of the magnocellular elements in hypothalami of fifty Long-Evans (normal) and Brattleboro (diabetes insipidus) rats was done using the unlabeled antibody enzyme technique (PAP) with primary antisera directed against oxytocin (OXY), vasopressin (ADH), and the neurophysins. The magnocellular neurons of the hypothalamus were found in the supraoptic (SON), paraventricular (PVN), and anterior commissural (ACN) nuclei, a number of accessory nuclei, and as individual cells in the anterior hypothalamic area. SON was divided by the optic tract into the principal part and retrochiasmatic SON. In retrochiasmatic SON a majority of the cells contained vasopressin. Within the principal part of SON oxytocin-producing cells tended to be found rostrally and dorsally, while the vasopressin cells were more common caudally and ventrally. PVN was divided into three subnuclei, the medial, lateral, and posterior subnuclei, on the basis of cellular morphology and peptide content. The magnocellular cells of the medial and lateral PVN were closely packed together and nearly round, while those of posterior PVN were more separated and fusiform in shape with their long axis running in a medio-lateral direction. Medial PVN consisted primarily of oxytocin-producing cells, while lateral PVN was formed by a core of vasopressin-producing cells with a rim of oxytocin cells. Posterior PVN contained largely oxytocin-producing cells. Both ADH and OXY cells were found in the accessory nuclei. In the Long-Evans rat the SON had, on the average, 1443 OXY and 3236 ADH cells; the PVN had 1174 OXY and 976 ADH cells; and the accessory magnocellular groups in the hypothalamus (including the ACN) had 1286 OXY and 552 ADH cells. The Brattleboro strain animal had similar numbers of cells in these nuclei. (The cells which contain ADH in normal animals were identified in the Brattleboro rat as large, neurophysin-negative cells.) Thus, a large fraction of the magnocellular oxytocin- and vasopressin-producing cells in the rat were located outside of the PVN and SON. One accessory cell group in particular, ACN, had 616 OXY cells, or about 50% as many as PVN. In each nucleus the sum of the numbers of OXY and ADH cells was approximately the number of neurophysin cells.
 ...
PMID:Immunohistochemical analysis of magnocellular elements in rat hypothalamus: distribution and numbers of cells containing neurophysin, oxytocin, and vasopressin. 701 60


1 2 Next >>