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)

Corticotropin-releasing factor (CRF) has been reported to be expressed in oxytocin-containing magnocellular neurosecretory neurons of the paraventricular (PVN) and supraoptic (SON) nuclei, and in Barrington's nucleus, a pontine micturition center. Each of these cell groups is known to play a role in fluid and electrolyte homeostasis. To gain a better understanding of the role of CRF in this context, the effects of osmotic stimulation and volume loading on CRF mRNA levels in the PVN, SON and Barrington's nucleus were examined using in situ hybridization histochemistry with an 35S-labeled cRNA probe. Adult male rats received either normal tap water (control), or hypertonic (2%) saline (HS) for up to 3 days. In a second experiment, normal saline was infused through a jugular vein cannula at 6 ml/h for 3 days; control rats were cannulated but received no infusion. Relative levels of CRF mRNA were compared by estimating both the number of positively hybridized cells and the density of silver grains in emulsion-dipped autoradiograms. HS treatment resulted in marked increases in CRF mRNA in the magnocellular neurosecretory system. All recognized oxytocinergic cell clusters, i.e., the anterior, medial and posterior magnocellural subdivisions of the PVN, the dorsal aspect of the SON, and components of the accessory magnocellular system, displayed this effect. By contrast, HS treatment resulted in significant decreases in CRF mRNA levels in the parvocellular (hypophysiotropic) division of the PVN and in Barrington's nucleus. By contrast, volume loading, which failed to affect plasma osmolality, significantly increased CRF mRNA levels in Barrington's nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of corticotropin-releasing factor mRNA in neuroendocrine and autonomic neurons by osmotic stimulation and volume loading. 148 95

Recent results have demonstrated altered corticotropin-releasing factor (CRF)-41 content of the neurointermediate lobe (NIL) of the pituitary gland in response to various manipulations including osmotic stimulation. This study was undertaken to determine whether changes in CRF-41 content of the NIL are accompanied by changes in intensity of CRF-41-like immunoreactivity (CRF-41-LI) of neurosecretory neurones of the hypothalamus in response to osmotic stimulation. Wistar rats of both sexes given either tap water ad libitum, 2% NaCl solution, or access to tap water was limited to 20 min daily, for 7 days. Subsets of rats from each group were adrenalectomized (ADX) or treated with dexamethasone (DEX). Thirty-six hour before perfusion with fixative consisting of buffered formaldehyde and picric acid, animals received 75 micrograms colchicine i.c.v. Forty micrometer thick vibratome sections were stained for CRF-LI, arginine vasopressin (AVP-LI) and oxytocin (OXY-LI) using the avidin-biotin-peroxidase complex method. In response to both types of osmotic stimulation magnocellular neurones of the paraventricular (PVN) and supraoptic nuclei (SON) showed increased CRF-LI, AVP-LI and OXY-LI, while CRF-LI of parvocellular perikarya of the PVN decreased. The enhanced CRF-LI seemed to appear in a subset of magnocellular neurones with OXY-LI but not AVP-LI. Increased staining intensities were also observed in magnocellular neurones in ADX rats challenged osmotically. In contrast, systemic DEX administration, as well as implantation of DEX in the area on the SON, sharply attenuated CRF-LI but not AVP-LI or OXY-LI of magnocellular neurones in osmotically stimulated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxytocinergic neurons in rat hypothalamus. Dexamethasone-reversible increase in their corticotropin-releasing factor-41-like immunoreactivity in response to osmotic stimulation. 211 29

1. The measurement of cellular mRNA content by quantitative in situ hybridization is a valuable approach to the study of gene expression in brain since this tissue exhibits a high degree of phenotypic heterogeneity. 2. The cellular content of vasopressin and oxytocin mRNA in hypothalamo-neurohypophysial system neurons was altered by maintaining rats for 24 hr on 2% sodium chloride water. 3. Statistical and graphical techniques were then used to analyze cell by cell how mRNA levels were altered as a result of osmotic stimulation. We propose that the negative binomial probability distribution is a suitable model to describe how mRNA content varies across a defined cell population. For both measures of oxytocin and vasopressin mRNA levels, maximum-likelihood estimation indicated that this model adequately described empirical findings obtained from rats drinking tap water or salt water. 4. Both graphical and statistical analyses suggested how the defined neural system responds to osmotic stimulation: mRNA content was altered as a multiplicative function of "initial state." The utility and limitations of the quantitative approach are discussed.
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PMID:Quantitative in situ hybridization to measure single-cell changes in vasopressin and oxytocin mRNA levels after osmotic stimulation. 233 46

1. Water uptake in vivo, and water fluxes across the isolated skin were studied in salt (NaCl) acclimated toads. 2. Water uptake of acclimated toads maintained in the solution of acclimation, decreased with the environmental salinity. 3. The osmotic water permeability (Pos) of the skin increased upon salt (NaCl) acclimation, both in vivo and in vitro. 4. Pos of the skin of toads acclimated to non-permeant solutes such as sucrose (230 mmol/l) or mannitol (400 nmol/l), was greatly reduced. 5. Oxytocin (syntocinon) increased the Pos both in tap water and salt acclimated toads. In high salt (greater than 200 mmol/l NaCl) acclimated toads however, the increased Pos and water flux at larger osmotic gradients, could not be stimulated further by the hormone. 6. The adaptive nature of the selective changes in the permeability properties of the skin under salt acclimation conditions is discussed.
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PMID:The effect of salt acclimation of the water uptake and osmotic permeability of the skin of the toad (Bufo viridis, L.). 350 23

In earlier ultrastructural studies of the supraoptic nucleus in adult rats we noted "free" and incompletely covered postsynaptic densities (collectively referred to here as vacant postsynaptic densities) on dendritic shafts. Free postsynaptic densities have been reported in other parts of the central nervous system of normal rodents. We investigated the possibility that physiological activation of the supraoptic cells, which produces changes in many aspects of their morphology, would alter the incidence of the free or incompletely covered postsynaptic densities on dendrites in the supraoptic basal dendritic zone. The cells of the supraoptic nucleus are activated to increase cell firing and secretion of oxytocin and/or vasopressin in response to dehydration, gestation, and lactation. We have examined: untreated virgin females; untreated males; 24 h water-deprived males; prepartum (21st day of gestation) females; postpartum females (on the day of parturition); lactating females (14 days of suckling); mothers 10 days after weaning their pups; females given 2% saline to drink (dehydrated) for 10 days; and females or males given 2% saline to drink for 10 days, then given tap water for 2 or 5 weeks to allow rehydration. Only long-term activation of the supraoptic nucleus by lactation or by drinking saline for 10 days brought about significant decreases in the percentage of dendrites with vacant postsynaptic densities. These densities did not reappear in saline treated rats which had been rehydrated for 2 weeks, but did return in both the 5-week rehydration and the 10-day postweaning groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vacant postsynaptic densities on supraoptic dendrites of adult rats diminish in number with chronic stimuli. 373 Dec 49

After dehydration, oral rehydration causes a fall in plasma arginine vasopressin (AVP) that precedes changes in plasma osmolality. To investigate further the stimulus for this effect, its specificity, and association with thirst, six volunteers were deprived of water for 24 h and given a salt load on two separate occasions. On each study day they then drank rapidly 10 ml/kg of either tap water or hypertonic saline (360 mosmol/kg). There was a significant fall in plasma AVP from 2.0 +/- 0.3 to 1.2 +/- 0.4 pmol/l (P less than 0.05) 5 min after drinking water and from 1.8 +/- 0.3 to 0.9 +/- 0.2 pmol/l (P less than 0.05) after hypertonic saline. Plasma osmolality fell 30-60 min after water and was unchanged after saline. Plasma renin activity, oxytocin, and total protein all remained unchanged. All subjects reported diminished thirst after hypertonic saline. Gargling with water reduced thirst but did not affect plasma AVP. There appears to be a drinking-mediated neuroendocrine reflex that decreases plasma AVP irrespective of the osmolality of the liquid consumed. The sensation of thirst did not correlate with plasma osmolality and was not always related to plasma AVP concentration.
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PMID:Oral hypertonic saline causes transient fall of vasopressin in humans. 374 Mar 1

I would like to comment on the letters of Dr. Bruce (August 19, p. 380) and Dr. Alderman (August 5, p. 279) concerning the part played by an inflated Foley catheter balloon in the uterus when abortion is being induced with extraamniotic (PGs) prostaglandins and/or oxytocin. That some mechanical stimulation of the uterus may result cannot be denied, but several factors have to be considered. The size of the balloon relative to that of the uterus no doubt plays an important part in the irritability produced, and the volume of the balloon in Dr. Bruce's investigation was much larger than that used by Alderman et al. (July 1, p. 5), and ourselves. If the balloon is too large, the dilation needed before it is expelled may be more than that required for fetal expulsion and the abortion may be unnecessarily delayed. On the other hand, if the baloon is too small it may be extruded prematurely, as Alderman et al. found. A further point is that if, occasionally, insertion of the catheter results in a bloody tap by disturbing the placental site, a greater than average degree of uterine contractility might ensue. In 2 cases we have inserted a Foley balloon (without obtaining a bloody tap) at 18 weeks gestation and inflated with 40 ml. of sterile water. Intrauterine activity was recorded for 18 hours via the open end of the Foley catheter. The amount of uterine activity produced was negligible, particularly when compared with that seen upon the addition of extraamniotic PGs.
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PMID:Abortion with extra-amniotic prostaglandins. 411 2

Sustained hyperosmolality increases the levels of hypothalamic oxytocin (OT) and arginine vasopressin (AVP) messenger ribonucleic acids (mRNAs). Gonadectomy is known to abolish this response (12,18). In this study we investigated whether thyroidectomy would alter OT and AVP mRNA levels in the hypothalamic paraventricular nucleus (PVN) of the hyperosmotically stimulated rat. Male Sprague-Dawley rats underwent thyroidectomy (hypothyroid) or sham thyroidectomy (euthyroid) at 7 weeks of age. Three weeks later hypothyroid and euthyroid animals were administered 2% NaCl (6-11 days) or tap water and sacrificed at the end of the experiment. Northern blot hybridization was used to assess size and levels of hypothalamic OT and AVP mRNAs. Hypothyroid rats had significantly lower levels of serum thyroxine (T4) than their euthyroid cohorts (P < 0.0001). Both the euthyroid and the hypothyroid animals receiving 2% NaCl developed hypernatremia and increased the levels and the size of OT and AVP mRNAs compared to their tap water cohorts. We conclude that in contrast to gonadectomy, thyroidectomy does not alter the level of OT and AVP mRNAs in the hypothalamus of chronically hypernatremic male rats.
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PMID:Thyroidectomy does not alter hypothalamic oxytocin and vasopressin expression in chronically hypernatremic rats. 760 12

Rats drinking ad libitum tap water or hypertonic (i.e. 2%) sodium chloride solution were given intracerebroventricularly (i.c.v.), for 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 decreased hypothalamic oxytocin content in both euhydrated (i.e. given tap water ad libitum) and salt-loaded rats. In rats drinking tap water, neurohypophysial oxytocin content decreased. Plasma oxytocin concentration was distinctly elevated under TRH treatment in rats euhydrated but, on the contrary, decreased in salt-loaded rats as compared with animals similarly drinking hypertonic saline but not TRH-treated. The present data suggest that TRH may be involved in some regulatory processes related to oxytocin biosynthesis and release from the rat hypothalamo-neurohypophysial system.
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PMID:Thyrotropin-releasing hormone (TRH) modifies oxytocin release from the hypothalamo-neurohypophysial system in salt-loaded rats. 767 Jan 25

The effect of hypertonic NaCl consumption on vasopressin (VP) and oxytocin (OT) mRNA levels and plasma and pituitary peptides was evaluated in rats with sham or anterior ventral third ventricular (AV3V) lesions. Rats were given tap water or 2% NaCl for 4 days. Because the rats with lesions drank significantly less salt solution than the controls (78.8 +/- 17.4 vs. 205.5 +/- 37.8 ml/4 days), a second control group was included in which saline intake was matched to the lesioned group. AV3V rats showed a deficit in the peptide response to the osmotic stimulus. There was no increase in plasma VP or OT or decrease in posterior pituitary peptide content in the face of an extreme hypernatremia: plasma sodium of 180.1 +/- 4.2 meq/l. Evaluation of mRNA changes by means of in situ hybridization showed that animals with lesions responded to the salt challenge with increases in hypothalamic VP and OT mRNA levels. There were significant increases in paraventricular and supraoptic OT mRNA and paraventricular VP mRNA in the lesioned group. The salt-matched control group showed no changes in peptide mRNA levels. These results demonstrate that AV3V lesions produce an impairment of the salt-neuroendocrine reflex but a persistence of the peptide mRNA response. Differences in control mechanisms must account for this dissociation between peptide mRNA expression and peptide secretion.
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PMID:Dissociation between vasopressin and oxytocin mRNA and peptide secretion after AV3V lesions. 781 Jul 75


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