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)

Rats drinking and libitum tap water or hypertonic (i.e., 2%) sodium chloride solution were given intracerebroventricularly (i.c.v.), during three days, thyrotropin-releasing hormone (TRH) in a daily dose of 200 ng dissolved in 10 microliters of 0.9% sodium chloride. Treatment with TRH resulted in significantly increased hypothalamic oxytocin content in both euhydrated (i.e., given tap water ad libitum) and salt-loaded rats and vasopressin content only in euhydrated rats. Similarly, neurohypophysial vasopressin and oxytocin content significantly increased in animals drinking tap water or 2% sodium chloride during treatment with TRH. The present data suggest that TRH may be involved in some regulatory processes to vasopressin and oxytocin biosynthesis and release from the rat hypothalamo-neurohypophysial system.
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PMID:Influence of thyroliberin (TRH) on hypothalamo-neurohypophysial vasopressin and oxytocin content of rats drinking 2% NaCl. 830 34

The acclimation of the clawed toad Xenopus laevis to hyperosmotic solutions of NaCl (balanced solution of sea salt), urea or mannitol was studied. The animals could not be acclimated to salt solutions more concentrated than 400 mosm.1-1. Urea was tolerated till 500 mmol.1-1. Plasma osmolality was always hyperosmotic to the environmental solution, but with diminished osmotic gradient at the highest tolerated solutions. Plasma urea concentration approached 90 mmol.1-1, similar in the three solutions of acclimation. Urine volume was very small under all conditions. Serum aldosterone and corticosterone did not differ significantly, although there was a slight tendency towards lower aldosterone in the NaCl solution. In vivo water uptake in tap water acclimated animals was very small, and was higher in the other groups. Only the salt- and urea-acclimated, but not the tap water and mannitol-acclimated groups responded with a clear increase following injection of oxytocin or theophylline. In vitro urea fluxes were similar and invariable in both directions under all conditions. No significant effect of theophylline was observed. Sodium transport measured by the short-circuit technique in vitro was lower in salt- and mannitol-acclimation conditions, and was stimulated significantly under all conditions in response to serosal oxytocin or theophylline. It is concluded that Xenopus laevis can osmoregulate at a limited range of external solutions. It is limited in the increase of its plasma urea concentration; the transport properties of the skin do not change very much upon acclimation, except for the hydroosmotic response to oxytocin.
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PMID:Mechanisms of hyperosmotic acclimation in Xenopus laevis (salt, urea or mannitol). 834 83

The dynamics of change in mitochondria-rich (MR) cells density in the skin epithelium of Bufo viridis was studied on skin biopsies taken in vivo, throughout experimental periods lasting up to 3 months. When the bathing solution contained Cl-, MR cells' density (Dmrc) greatly decreased. There was one exception, when the acclimation solution was KCl, Dmrc in the skin increased. The rate of decrease in Dmrc depended on the mode of acclimation. When bath NaCl concentration was elevated slowly in small increments, the change in Dmrc was very slow. A regression line was calculated for the rate of decrease in the density of MR cells. An equation in the form of y = 1574 - 10.23x (where x = days; R2 = 0.626) was obtained with bath NaCl that was elevated from 30 to 200 mmol/l, in 45 days. Oxytocin (60 mU/ml) increased sodium transport, independently and without effect on Cl- conductance. Theophylline (1 mmol/l), which leads also to elevation of cellular cAMP in contrast, increased Na+ transport, but elevated Cl- conductance 3-4 times as well. Cl- conductance that is activated by transepithelial potential was much lower in skin from hyperosmotic NaCl-acclimated toads, as compared with that in skin from tap water-acclimated animals. Our experiments confirm that MR cells are a major pathway for Cl- conductance, as suggested earlier. However, the density of these cells in the skin epithelium of B viridis depends not only on bath NaCl concentration, but also on the mode of acclimation of the animals. Since transport functions other than gCl reside in the amphibian skin MR cells, the density of MR cells must also depend on these functions. These functions, and the mechanisms responsible for the down and up regulation of MR cells' density, remain to be established.
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PMID:Dynamics and density of mitochondria-rich cells in toad skin epithelium. 878 20

Ultrastructural studies of the supraoptic nucleus (SON) of the hypothalamus suggest that an active retraction and extension of astrocytic processes (structural plasticity) from between magnocellular neuroendocrine neurons plays a role in the release of oxytocin, vasopressin, or both peptides that accompanies parturition, lactation, and dehydration. In support of this, Salm et al. (1985) previously demonstrated a lactation-associated reduction in immunoreactive glial fibrillary acidic protein (GFAP), an astrocyte-specific cytoskeletal constituent. To determine if similar changes occur in response to dehydration, and if they are reversible, the present study examined GFAP-immunoreactivity (IR) in the SON under various hydration states. Rats were dehydrated for 7 days by substitution of drinking water with 2% saline (n = 3), or dehydrated for 7 days followed by 7 days of rehydration (n = 3). A control group (n = 3) with free access to tap water was used for comparisons. The optical density of GFAP-IR was obtained from the SON, globus pallidus, and lateral hypothalamic regions. The areas of the ventral glial limitans subjacent to the SON (SON-VGL) and of linearly equivalent segments of glial limitans more distant from the SON were also determined. Dehydration resulted in a significant reduction in GFAP-IR in the SON compared to control and rehydrated levels. We also found that the area of the SON-VGL was significantly larger than that of linearly equivalent segments of glial limitans elsewhere and that it was significantly reduced in dehydrated rats, returning to control levels with rehydration. GFAP-IR and glial limitans thickness in regions unrelated to body fluid homeostasis lateral to the SON, overlying to dorsal cortex, and subjacent to the optic chiasm were not significantly changed by hydration state. These results are similar to the changes of GFAP-IR reported for lactating rats and provide further evidence for a role of structural plasticity of astrocytes in events surrounding the selective functional activation of local neurons.
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PMID:Dehydration and rehydration selectively and reversibly alter glial fibrillary acidic protein immunoreactivity in the rat supraoptic nucleus and subjacent glial limitans. 948 12

The neuropeptides arginine vasopressin (AVP) and oxytocin (OT) have been implicated in the genesis of hypertension due to deoxycorticosterone acetate (DOCA)-salt treatment of uninephrectomized rats. In this work, we studied if DOCA treatment of intact rats in doses arousing a salt appetite (a prehypertensive state), modulated mRNA for AVP and OT in the hypothalamus. Male Sprague-Dawley rats were offered both tap water and 3% NaCl in separate bottles and received vehicle or subcutaneous injections of 10 mg DOCA on alternate days for 7 days (4 injections) or 17 days (9 injections). They developed a preference for 3% NaCl solutions 24-48 h after treatment. Brain slices from rats killed on the 8th or 18th day were exposed to 35S-labeled probes encoding prepro-AVP mRNA or OT mRNA, respectively. Expression of these mRNAs was measured in the magnocellular and parvocellular divisions of the paraventricular nucleus (PVN) and magnocellular cells of the supraoptic nucleus (SON). No changes were obtained in neuropeptide mRNA levels in the parvocellular division of the PVN between control and the two groups of DOCA-treated rats. However, DOCA-treated animals presented an increased number of grains per cell for AVP mRNA in the magnocellular division of the PVN and in magnocellular cells of the SON, as shown by group mean comparisons and frequency histograms. No changes were detected for OT mRNA. In a second series of studies, control or DOCA-treated rats were offered 3% NaCl or water as the only choice. Animals drinking 3% NaCl showed increased AVP and OT mRNA levels, whether they received DOCA or not. However, AVP mRNA levels in both nuclei were higher in DOCA-treated rats drinking 3% NaCl than in controls drinking salt solution. In comparison, control and DOCA-treated rats drinking water showed lower levels of AVP mRNA. OT mRNA levels in the SON remained unchanged in the same groups. The results suggest that in the magnocellular cells of the PVN and SON, increments in AVP mRNA are obtained following increments in salt intake produced by either mineralocorticoid treatment or exclusive salt drinking. In rats offered salt solution and water to drink, DOCA effects on AVP mRNA developed before changes occurred in serum sodium levels. Because combined DOCA + salt treatment induced a higher response in terms of AVP mRNA expression, we suggest that AVP could be a target of the central effects of the mineralocorticoid.
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PMID:Increased expression of magnocellular vasopressin mRNA in rats with deoxycorticosterone-acetate induced salt appetite. 970 77

It was shown previously that luteinizing hormone-releasing hormone (LHRH) affects the neurohypophysial oxytocin release in water-deprived rats. However, the detailed mechanisms by which LHRH modifies the oxytocin response to hyperosmotic stimulation have not been explained so far. Using the isolated hypothalamo-neurohypophysial explants obtained from euhydrated rats, the effect of LHRH on the oxytocin secretion was studied under conditions of direct osmotic (i.e., Na(+)- evoked) as well as nonosmotic (i.e., K(+)-evoked) stimulation. Additionally, the oxytocin response to LHRH was investigated using the explants obtained from animals drinking 2% saline for eight days (systemic, i. e., both direct and indirect, osmotic stimulation). LHRH significantly enhanced Na(+)- and K(+)-evoked oxytocin release from explants taken from rats drinking tap water, indicating that LHRH could affect the Na(+)/K(+)-dependent depolarization of perikarya of oxytocin neurones. In contrast, LHRH significantly diminished the K(+)-stimulated hormone release when the neurohypophysial complex was obtained from previously salt-loaded rats, suggesting that peripheral osmotic stimulation somehow modifies the sensitivity of oxytocinergic neurones to LHRH (possible mechanisms are discussed). It is concluded that LHRH may participate in the regulation of oxytocin secretion via both direct and indirect impact on magnocellular oxytocinergic neurones depending on the current functional status of the hypothalamo-neurohypophysial complex.
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PMID:Luteinizing hormone-releasing hormone and oxytocin response to hyperosmotic stimulation: in vitro study. 1085 29

The presence of corticotropin-releasing hormone (CRH) receptors type-1 (CRHR-1) and type-2 (CRHR-2alpha) in the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei, and the effects of i.c.v. injection of CRH and urocortin on arginine vasopressin (AVP) and oxytocin release, have suggested that CRH ligands have a role in osmoregulation. In this study, double labelling in situ hybridization using 35S-labelled CRHR-1 or CRHR-2alpha and digoxigenin-labelled AVP, oxytocin or CRH riboprobes was employed to examine the localization of CRHR-1 or CRHR-2alpha mRNA in the SON and PVN of control and osmotically stimulated rats. Rats received an i.p. hypertonic saline (1.5 M) injection or isotonic saline injection (controls), or 2% NaCl intake (salt loading) or tap water (controls) for 12 days. While CRHR-1 mRNA was undetectable in the SON and PVN in control rats, its expression was increased markedly at 4 h after i.p. hypertonic saline injection or after 12 days salt loading. Of the cells labelled with digoxigenin-AVP, 53% in the SON and 90% in the PVN coexpressed CRHR-1 mRNA after i.p. hypertonic saline injection. In oxytocinergic neurones, 73% in the SON and 91% in the PVN showed CRHR-1 autoradiographic grains higher than background levels after i.p. hypertonic saline injection. In addition, i.p. hypertonic saline induced CRHR-1 mRNA expression in digoxigenin-CRH stained cells in the parvocellular PVN. CRHR-2alpha transcripts were present in both the SON and PVN under basal conditions, and salt loading, but not acute i.p. hypertonic saline injection, further stimulated this expression. Double labelling in situ hybridization showed colocalization of CRHR-2alpha mRNA with AVP and oxytocin mRNA in the SON. These studies support a role for CRH and urocortin regulating the hypothalamo-neurohypophyseal system, and suggest a direct action of the peptides in the magnocellular neurones.
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PMID:Vasopressin and oxytocin neurones of hypothalamic supraoptic and paraventricular nuclei co-express mRNA for Type-1 and Type-2 corticotropin-releasing hormone receptors. 1097 8

Male mice (9-13 mo of age) in which the gene for oxytocin (OT) had been deleted (OT -/-) were administered 0.5 M sodium chloride (NaCl) solution or tap water as a two-bottle choice test following overnight fluid deprivation (1600 to 1000 the following day). Compared with wild-type cohorts (OT +/+), OT-deficient mice ingested sevenfold greater amounts of saline in the first hour following reintroduction of fluids, P < 0.001, and fourfold greater amounts at the end of 6 h, P < 0.02. No significant difference in total water ingested was noted between the two genotypes at the end of either 1 or 6 h. If food deprivation accompanied the overnight fluid deprivation and food was reintroduced 1 h after the reintroduction of both water and saline, OT -/- mice still ingested greater amounts of saline, but not water, than OT +/+ mice at both 1 h, P < 0.001, and 6 h, P < 0.02. No differences were noted between genotypes in the daily intake of 0.5 M NaCl solution or water during a 3-day observation period before the overnight fluid deprivation. The volume of saline consumed in each 24-h observation period represented about one-tenth of the total fluids ingested in each genotype. We conclude that OT -/- mice display an enhanced salt appetite compared with OT +/+ mice when fluid deprived overnight. The salt appetite was only apparent in the presence of a perturbation such as fluid deprivation, which predisposes the animal to moderate hypovolemia. The observations support an inhibitory role for OT in the control of sodium appetite in mice.
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PMID:Mice deficient in oxytocin manifest increased saline consumption following overnight fluid deprivation. 1164 Nov 4

Effects of repeated daily intracerebroventricular injections of 1 microg of glucagon-like peptide-1 (7-36) amide (tGLP-1) on feeding and drinking behaviour, as well as neurohypophysial hormone secretion, was investigated in rats drinking tap water or 2% saline for 6 days. In euhydrated rats, tGLP-1 decreased moderately food and water consumption without a marked reduction of body weight. In salt-loaded rats, tGLP-1 considerably inhibited saline intake. On the other hand, food consumption and body weight changes were similar in vehicle- and tGLP-1-treated rats drinking 2% saline. Osmotic stimulation resulted in the augmented release of both neurohypophysial hormones. tGLP-1 did not alter plasma vasopressin and oxytocin concentrations either in euhydrated or osmotically stimulated rats. It is concluded that tGLP-1 may modify feeding and drinking behaviour under conditions of normal or disturbed water-electrolyte balance in the rat.
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PMID:Effects of tGLP-1 on feeding behaviour and neurohypophysial function under chronic osmotic stimulation. 1253 13

Intact and ovariectomized oxytocin (OT)-deficient (OT-/-) and wild-type (OT+/+) mice were tested for consumption of 0.5 M NaCl solution or tap water in a 2-bottle choice test. During 3 days of acclimation, voluntary ingestion of NaCl was equal between genotypes. After overnight fluid deprivation, intact OT-/- mice ingested 2 times more NaCl solution than OT+/+ mice in the 6th hr, but not the 1st hr, after reintroduction of fluid. Ovariectomized mice consumed less than intact mice after overnight fluid deprivation. When a 0.2 M NaCl solution was administered for 6 days in ovariectomized mice, OT-/- mice voluntarily consumed greater amounts than OT+/+ mice. After overnight fluid deprivation, consumption by OT-/- mice was 3 times that of OT+/+ mice at 1 hr and 2-fold greater after 6 hr. Enhanced intake of NaCl-containing solutions in female OT-/- mice suggests that central OT may be an important inhibitor of sodium consumption.
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PMID:Consumption of solutions containing sodium chloride is enhanced in female oxytocin-deficient mice. 1261 5


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