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)

Naloxone and its congener, methyl naloxone, were given subcutaneously (s.c.) or centrally (i.c.v.) to 24-h water-deprived male rats 30 min prior to decapitation and the effect on plasma levels of vasopressin (VP) and oxytocin (OT) was studied. The potency of s.c. applied methyl naloxone to increase plasma OT levels did not differ from that of naloxone. Injected i.c.v., neither methyl naloxone nor naloxone had a clear effect and they antagonized i.c.v. co-administered dynorphin A-(1-13) equipotently. Methyl naloxone or naloxone, s.c., antagonized the inhibitory action of simultaneous dynorphin A-(1-13) and beta-endorphin-(1-31) given i.c.v., although higher doses of methyl naloxone were required. The data indicate that the sites of inhibition of neurohypophysial hormone release due to beta-endorphin-(1-31) are more likely to be located mostly within the blood-brain barrier, to which methyl naloxone has less ready access, than are the sites of inhibition due to dynorphin A-(1-13).
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PMID:Pharmacological assessment of the site of action of opioids on the release of vasopressin and oxytocin in the rat. 168 Jul 8

An ultrastructural analysis of post-embedding glutamate immunocytochemistry within the neural lobe of the pituitary was used to explore the possible role of glutamate within the magnocellular neuroendocrine cells. Relative densities of a colloidal gold marker associated with various cellular and subcellular compartments of the neural lobe were quantified by computer analysis of electron micrographs. Robust glutamate immunoreactivity was observed in both pituicytes (cytoplasm, mitochondria and nucleus) and neurosecretory endings. Within the neurosecretory endings, glutamate staining was specifically localized to the microvesicles with no overlap into the neurosecretory granule population. Stimulation of the vasopressin/oxytocin neurosecretory system by water deprivation increased glutamate content in pituicytes and mitochondria within neurosecretory endings but had little influence on microvesicle glutamate content. The results are consistent with the existence of multiple functional pools of immunoreactive glutamate in both pituicytes and neurosecretory endings. Microvesicles within the neurosecretory endings exhibit many properties of secretory vesicles, appear to be functionally independent of the neurosecretory granules, and have sufficient glutamate immunoreactivity to suggest that this amino acid may be compartmentalized for release in the neural lobe.
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PMID:Ultrastructural distribution of glutamate immunoreactivity within neurosecretory endings and pituicytes of the rat neurohypophysis. 168 73

In situ hybridization histochemistry and indirect immunofluorescence histochemistry were used to study changes in the expression of vasopressin (VP), oxytocin (OXY), tyrosine hydroxylase (TH), galanin (GAL), dynorphin (DYN) and cholecystokinin (CCK) in hypothalamic magnocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of rats. After prolonged administration of 2% sodium chloride as drinking water (salt-loading), the treatment increased the levels of VP, OXY, TH, GAL, DYN and CCK mRNA in the PVN and SON. The increase in CCK mRNA was, however, proportionally higher in the PVN than in the SON. Within cell bodies of the PVN and SON of salt-loaded rats, a depletion of VP- and OXY-like immunoreactivity (LI) and an increase in TH-LI were seen. In salt-loaded/colchicine-treated rats, a marked decrease in GAL- and DYN-LI, but no specific changes in CCK-LI were observed. Within nerve fibers of the posterior pituitary of salt-loaded rats, a marked depletion of VP-, GAL- and DYN-LI was found. Less pronounced depletion was observed in OXY- and CCK-LI, and no specific changes in TH-LI were seen. The results show that high plasma osmolality induces increased mRNA levels for VP, OXY, TH, GAL, DYN and CCK, presumably indicating increased synthesis, an increased export from cell somata of VP, OXY, GAL and DYN, and a decrease in levels of these peptides in the posterior pituitary, suggesting increased release. The catecholamine-synthesizing enzyme TH, however, which has a cytoplasmic localization and is not released from nerve endings, remains high in the cell bodies and nerve endings during this state of increased activity.
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PMID:Peptides and transmitter enzymes in hypothalamic magnocellular neurons after administration of hyperosmotic stimuli: comparison between messenger RNA and peptide/protein levels. 169 5

Vasopressin action in the renal collecting duct is believed to be mediated by the cycling of water channels in principal and, possibly, intercalated cells. We used 6-carboxyfluorescein (6-CF) or fluorescein-labeled dextran (FITC-dextran) to determine the location and water permeability of endocytic vesicles from papilla and inner stripe of Brattleboro rats in different states of diuresis. Fifteen minutes after FITC-dextran infusion, fluorescent vesicles were concentrated at the apical pole of principal and intercalated cells. The osmotic water permeability (Pf) of these endosomes was measured by fluorescence quenching. In papillary endosomes, Pf was high (0.04 +/- 0.004 cm/s) when rats were in physiological states of antidiuresis or after treatment with vasopressin, 1-desamino-8-D-arginine vasopressin (DDAVP), or oxytocin; endosomes isolated from these regions of untreated animals had a low Pf. The number of papillary endosomes with high Pf increased with increasing doses of DDAVP. Endosomes from the inner stripe also had a high Pf only after vasopressin treatment. Confocal microscopy of sections of papilla showed that vasopressin significantly increased endocytosis in principal cells but had no effect on intercalated cells. Our data demonstrate that the bulk of fluorescently labeled vesicles from the papilla originate from the apical membrane of principal cells and contain water channels in their limiting membrane only when the rats are in physiological states of antidiuresis. In contrast, the majority of endocytosis in intercalated cells is not involved in water channel recycling.
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PMID:Endocytosis of water channels in rat kidney: cell specificity and correlation with in vivo antidiuresis. 170 69

Endothelin-3-like immunoreactivity (ET-3-ir) was detected in extracts of rat hypothalamic median eminence, and in the anterior and neurointermediate lobes of the pituitary at levels (ng ET-3/mg protein) exceeding those present in extracts of abdominal aorta. This ET-3-ir appeared authentic because radioimmunoassay (RIA) dose-response curves parallel to those of synthetic ET-3 could be constructed and this ET-3-ir comigrated on C-8 high-pressure liquid chromatography (HPLC) with synthetic ET-3. Endothelin-1-like immunoreactivity, on the other hand, was abundant in extracts of abdominal aorta and cerebral cortex and only minimally present in hypothalamus and anterior pituitary gland. Central administration of 11 and 23 pmol ET-3 resulted in significant (4.2- and 5.7-fold, respectively) elevations of plasma levels of vasopressin. Oxytocin levels were transiently, yet significantly, elevated (1.8-fold) by the higher dose of ET-3. These results, and our findings that central administration of ET-3 inhibits stimulated water drinking, suggest a physiologically important role for endogenously produced endothelin in the central mechanisms regulating fluid and electrolyte homeostasis.
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PMID:Hypothalamic endothelin: presence and effects related to fluid and electrolyte homeostasis. 172 77

We examined the responses of vasopressin-neurons (VP-neurons) and oxytocin-neurons (OT-neurons) to acute salt-loading in a group of conscious rats (CON, n = 8) and rats under sodium pentobarbital (NEM, 50 mg/kg, i.p., n = 8) or urethane (URE, 1.6 g/kg, i.p. n = 8) anesthesia. Fifteen minutes following the induction of anesthesia, sodium pentobarbital produced an increase in basal plasma osmolality (Posm, 290 +/- 2 to 296 +/- 3 mosm/kg H2O, p less than 0.007) while urethane did not change basal Posm (287 +/- 2 to 289 +/- 2 mosm/kg H2O). Neither anesthetic agent resulted in any significant changes in basal plasma levels of vasopressin-associated neurophysin (VP-RNP) and oxytocin-associated neurophysin (OT-RNP). In response to intravenous infusion of 18% saline, all three groups of rats had similar rises in Posm. The slopes of the relationship between the rise in plasma VP-RNP and the rise in Posm were markedly reduced in both groups of anesthetized animals compared to that observed for conscious animals (CON = 2.54 +/- 0.5; NEM = 1.22 +/- 0.18; URE = 1.17 +/- 0.24 fmol.ml-1.mosm-1.kg H2O-1 p less than 0.0126). The slopes of the relationship between the rise in plasma OT-RNP and the rise in Posm were not significantly (p less than 0.4478) different between the CON group and the NEM group, while the slope for the URE group was significantly (p less than 0.05) smaller than that for the CON group (CON = 10.9 +/- 1.5; NEM = 9.3 +/- 1.5; URE = 6.3 +/- 0.7 fmol.ml-1.mosm-1.kg H2O-1).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of pentobarbital and urethane on release from magnocellular neurons. 174 63

A method for reducing complications from retained tissue requiring readmission after a legally induced 1st trimester abortion is evaluated. Prior attempts had been made to ascertain the reason for an annual 6% of 22,000 readmission rate. 117 women ages 18-42 years requesting legal abortion participated in this study at Bispebjerg Hospital, Copenhagen, Denmark. 47% were primagravida and the median age was 29.5 years. This study determined gestational age of 77-12 weeks by ultrasound for measuring crown-rump length. The abortion was performed by vacuum aspiration, followed by curettage and iv administration of oxytocin 10. Aspirated tissue was measured, after removal of blood clots, in a tube contain g 50 ml of water to eliminate air bubbles. Readmission due to infection or bleeding within the nest month was recorded. Tissue removed in a reevacuation was examined microscopically to ascertain placental or decidua tissue. The results of the analysis using Mann- Whitney's rank sum test for unpaired data revealed a significant difference in amount of aspirated tissue between 7-8 and 9-10 weeks (p.01) and also between 9-10 and 11-12 weeks (p.01). 5% or 6 patients were readmitted of whom 4.2% or 5 required a recurettage because of excessive bleeding. In 3 cases (2.5%) villi chorii were found on histological examination. 2 had a retroverted uterus and all 3 were 8-9 weeks gestation, 25 years, and primagravida. The retroversion would create more difficulty in emptying. It is recommended that retained tissue should be suspected when the amount of tissue after aspiration is 15 ml in the weeks 7-8, 25 ml in the weeks 9-10 and 35 ml in the weeks 11-12 of gestation.
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PMID:First-trimester legally induced abortions. The amount of aspirated tissue in relation to gestational age. 177 67

Human myometrial strips were excised at hysterectomy and cesarean section and allowed to contract spontaneously in a water bath. Porcine myometrial strips from midpregnancy were also collected. Recombinant human relaxin completely inhibited spontaneous myometrial activity in the pig at a concentration of 0.6 micrograms/mL, but human relaxin had much less of an effect or no effect on human myometrium at concentrations up to 7.5 micrograms/mL. Any effect of human relaxin on human myometrium was seen only in estrogen-primed human tissues; that effect was never greater than a 5% reduction in amplitude and 50% reduction in frequency. When contractions were stimulated with oxytocin or prostaglandin F2 alpha, relaxin had no inhibitory effect on either porcine or human myometrium at doses up to eight times the concentration of relaxin that had attenuated spontaneous contractions. Pretreatment with progesterone did not enhance the action of relaxin on human myometrium. The limited effect of human relaxin on human myometrium as compared to the marked inhibitory action of both porcine and human relaxin on porcine myometrial activity suggests that the species specificity does not lie with the relaxins but with the target tissues. Human relaxin H2 might not play a major role in the control of myometrial activity in the human.
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PMID:Human relaxin. In vitro response of human and pig myometrium. 177 23

The effect of oxytocin on feeding and drinking behaviours was compared in male and female rats. Dose-dependent feeding and drinking inhibition was observed in either sex to about the same degree, both following intracerebroventricular or intraperitoneal administration. The results were obtained whether in animals with free access to food and water or in schedule-fed animals fasting for 21h and in two different models of thirst (water deprivation for 16h, s.c. administration of hypertonic saline). These data show that there is no sexual dimorphism in oxytocin-induced inhibition of feeding and drinking.
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PMID:Oxytocin-induced inhibition of feeding and drinking: no sexual dimorphism in rats. 179 26

It was found that acetylcholine (ACh) at the concentration of 10(-3) M inhibited ADH-stimulated water transport through the wall of amphibian urinary bladder. This effect was suggested to be caused by an interaction of ACh with acetylcholinesterase (AChE) rather than by a stimulation of the M- or N-cholinoreceptor. The inhibitory action of ACh was completely suppressed in the presence of various AChE inhibitors (physostigmine, proserine, armine, Gd-42, acridine-iodmethylate), while an inhibitor of butyrylcholinesterase (BuChE), AD-4, failed to affect it. In accord with this observation the activity of AChE (but not of BuChE) was demonstrated in the urinary bladder epithelium. Since, in addition to the hydrosmotic effects of pituitrine, 8-arginine-vasopressin or oxytocin, ACh blocked also effects of forskolin or cyclic AMP, one may conclude that it acts at some post-cyclic AMP production stage. AChE-dependent inhibition of the ADH-stimulated water transport decreased significantly when the serosal pH was raising from 7.2 to 8.0, but was augmented by serosal acidification (pH 6.8), whereas such pH alterations did not affect the activity of the epithelium AChE. The effect of ACh under consideration was suppressed by adding amiloride (10(-4) M) to the serosal solution. Similarly, the ACh effect was blocked by an inhibitor of Ca-dependent K+ channels, 4-aminopyrdine, which in addition prevented the inhibition of the ADH-stimulated water transport by the serosal acidification. It was noteworthy that some other K+ channel blockers (Ba2+, Cs+, tetraethylammonium, apamine, quinine) did not affect either the water transport or the antipituitrine effect of ACh. In conclusion, we suggest that the inhibitory action of ACh on the ADH-stimulated water transport in the urinary bladder is mediated through the intracellular acidification resulting from ACh interaction with AChE. It is unlikely that the acidification is merely a consequence of the ACh hydrolysis, rather the ACh-AChE interaction induces directly an increase in the proton conductivity of the basolateral membrane of the urinary bladder epithelium.
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PMID:[Acetylcholinesterase and the ADH-dependent transport of water in the amphibian bladder]. 181 71


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