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)

We examined the effects of several in vitro experimental systems on the apparent potencies of putative secretagogues for stimulating ACTH release from rat anterior pituitary cells. Cells were prepared by trypsin digestion and gentle mechanical dispersion. Aliquots of the same cell preparations were tested in 1) a microperifusion system immediately after dispersion (day 0), 2) the same microperifusion system after 4 days of static suspension culture on a layer of Sephadex G-10 gel particles (day 4), 3) a static suspension system after 4 days of static suspension culture, and 4) a static monolayer system after 4 days of monolayer culture. Ovine CRF stimulated release of similar amounts of ACTH in all of the systems on days 0 and 4, except in one experiment, in which the response was less on day 4. Arginine vasopressin (AVP), oxytocin, and angiotensin II all appeared to be more potent in day 4 than in day 0 cells in the perifusion system, and the synergism of AVP with ovine CRF was also increased. Dioctanoylglycerol, which directly activates protein kinase-C, and forskolin, which directly activates adenylate cyclase, both stimulated greater release in day 4 cells. The mechanism(s) responsible for the difference in the responses of day 0 and day 4 cells is unknown. Epinephrine had only a small effect in the microperifusion system, but both epinephrine and norepinephrine had potencies comparable to AVP in the static suspension and monolayer systems. This was not due to prolonged exposure to the catecholamines, suggesting that these agents may act on other anterior pituitary cells to release metabolic products that secondarily stimulate the corticotrophs to release ACTH. The same situation appears to be true for atrial natriuretic factor. Gastrin-releasing peptide, its bioactive COOH-terminal half, which was active in a rat urinary bladder smooth muscle assay, its amphibian analog, bombesin, and cholecystokinin (26-33) were devoid of ACTH-releasing activity in all of the systems, in contrast to the findings of others. Since 4-day culture of dispersed cells improved most of their responses and diminished none, we postulate that they may more closely resemble normal pituitary cells in function, and since cellular metabolites are unlikely to accumulate in the interstitial fluid of the pituitary gland, we propose that the secretory functions of cells in perifusion systems may more closely resemble those in the pituitary gland in situ than they do in static incubation systems.
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PMID:Effects of several in vitro systems on the potencies of putative adrenocorticotropin secretagogues on rat anterior pituitary cells. 283 88

The direct effect of vasopressin on adrenal steroidogenesis and its effect on angiotensin II- and adrenocorticotropic hormone (ACTH)-stimulated steroidogenesis was evaluated by using an isolated perfused canine adrenal gland preparation. Infusions of vasopressin alone (50, 100, or 250 pg/ml perfusate) had no significant effect on the secretion of either aldosterone or cortisol. Infusions of vasopressin at 75 or 250 pg/ml perfusate during stimulation of steroidogenesis by angiotensin II or by ACTH did not cause a consistent increase in aldosterone secretion. In contrast, infusion of 250 but not 75 pg vasopressin/ml perfusate caused a consistent enhancement of ACTH-stimulated cortisol secretion. The infusion of a vasopressin V1-receptor agonist, but not of either a vasopressin V2-receptor agonist or oxytocin, also caused a significant enhancement of ACTH-stimulated cortisol secretion. These results suggest that the sensitivity of fasciculata cells to vasopressin is greater than that of glomerulosa cells. Finally, levels of vasopressin reported to occur in plasma during severe hemorrhage appear to be capable of enhancing cortisol secretion by a direct action on the adrenal gland via a V1-receptor mechanism.
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PMID:Effect of vasopressin on adrenal steroidogenesis. 284 63

The anterior hypothalamus has been implicated in the regulation of hydromineral balance, drinking, vasopressin release, sodium excretion and blood pressure control. Using anaesthetized rats, we have looked at the activity of cells in this region through using a recording electrode cemented to a 7 barrelled iontophoretic electrode inserted ventrally. Cells were tested for their responsiveness to iontophoretic application (Io) of angiotensin II (AII), vasopressin (AVP) and oxytocin (Ox). Of the 47 cells found to responsive to Io glutamate, 23 increased firing to AII, 18 to AVP and 6 to Ox. Nine cells responsive to AVP also responded to AII. Two cells responded to both Ox and AII. It appears that this rostral diencephalic area has neurons sensitive to more than one of the hormones implicated in the various responses involved in hydromineral regulation.
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PMID:Iontophoretic application of angiotensin II, vasopressin and oxytocin in the region of the anterior hypothalamus in the rat. 285 16

The possible relationship between the renin-angiotensin system and water balance in the toad Bufo arenarum has been indirectly explored. A positive correlation was found between the hydrosmotic response of ventral pelvic toad skin to angiotensin II (A II) and some age indicators (body weight, snout-urostyle length or head width). A different hydrosmotic response for oxytocin and isoproterenol (but not for A II) was found between four cutaneous regions of toad body. We conclude that A II may not be directly involved in the regulation of water balance mediated by water absorption across the skin of Bufo arenarum toads.
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PMID:Comparative effects of angiotensin II on osmotic water permeability in the toad (Bufo arenarum). 288 46

The contractile effects of 19 factors on isolated human arterial segments at term pregnancy were quantified, and 14 contractile agents were similarly applied to preterm (23 to 35 weeks) umbilical arteries. Responses to potassium chloride were used to normalize the data. At comparison with the term vessel, the preterm artery contracted more to angiotensin II and arachidonic acid and was more sensitive to oxytocin. Contractions were greater in term arteries to vasopressin, norepinephrine, prostaglandin D2, and prostaglandin E2 but similar in both group of arteries to bradykinin, histamine, acetylcholine, and prostaglandin F2 alpha. Neuropeptide Y, linoleic acid, uridine triphosphate, and thrombin were ineffective. Hyperoxia inconsistently induced weak, short-lived contractions. Contractions to cooling manifested marked desensitization and tachyphylaxis. Serotonin was the only agonist that displayed the pharmacodynamic features most likely to be important for closure: potency, efficacy, and long duration of action (greater than 2.5 hours). It was postulated that cellular elements surrounding umbilical vessels are primary sources of vasoactive agents that are important to closure of the fetoplacental circulation at birth.
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PMID:Pharmacodynamic study of maturation and closure of human umbilical arteries. 291 87

We have reported that microinjection of angiotensin II (ANG II) into the nucleus tractus solitarius of urethan-anesthetized normotensive rats produces an increase in mean arterial pressure (MAP) over the dose range 50-500 pmol. The effect in spontaneously hypertensive rats (SHR) is now reported. Over the range 100-500 pmol SHR exhibit increases in MAP and heart rate greater than Wistar-Kyoto or Sprague-Dawley rats. SHR did not exhibit exaggerated responses to intravenous phenylephrine, suggesting a central site of increased responsiveness to ANG II. We also found depressor effects in Sprague-Dawley at lower doses (0.1 and 1 pmol). The decreases in MAP were extremely variable and not dose related. A selected dose of additional neuropeptides identified in the NTS was tested. Somatostatin, bradykinin, and vasoactive intestinal peptide (0.5 nmol) were without cardiovascular effects. Oxytocin and vasopressin, however, produced significant increases in MAP. Substance P produced a very small but significant increase in heart rate and MAP. Interaction between the vasopressin and ANG II pressor effects was studied, and each proved to be independent.
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PMID:Neuropeptide action in nucleus tractus solitarius: angiotensin specificity and hypertensive rats. 293 Oct 31

Extracellular recordings were obtained in anaesthetized rats from single neurons located in various structures around the rostral end of the third ventricle, known to harbour integrative neurons sensing deficiencies in and originating corrective responses for water-electrolyte balance. Once arginine vasopressin (AVP) responsive neurons were located, a selective antidiuretic agonist (binding to V2 receptors) and either V1 (pressor response related) or V2 (antidiuretic) antagonists were iontophoretically applied. Neurons in this region did not respond to the V2 agonist and only the V1 antagonist was able to block the response to AVP. It is assessed that the investigated region has neurons equipped only with receptors of the V1 type. Interestingly, a number of these neurons also responded to angiotensin II (AII), oxytocin and to blood pressure changes. The integrative neuronal population of parasagittal rostrodiencephalic neurons seem therefore to sense indices of haemodynamic changes including their neuro-hormonal signals within the brain such as AII and AVP which bind to V1 (pressor response related) receptors.
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PMID:Evidence for vasopressin V1 receptors of rostrodiencephalic neurons: iontophoretic studies in the in vivo rat. Responses to oxytocin and to angiotensin. 297 Feb 80

Suspensions of rat anterior pituitary cells were exposed to corticotropin-releasing factor (CRF) (5 nM) and various neurohormones (0.002-1000 nM). CRF-induced secretion of ACTH was doubled by 0.1 nM arginine vasopressin (AVP), 0.2 nM arginine vasotocin, 1 nM oxytocin, 10 nM angiotensin II, and 100 nM noradrenalin; vasoactive intestinal peptide had no effect at 0.2-200 nM. CRF potentiation by AVP was also observed at lower concentrations of CRF. Since AVP appeared to be the most potent modulator of CRF-induced ACTH secretion, potentiation was further tested with specific antidiuretic and oxytocic agonists. Potentiation was clearly related to pressor biological activity, less so to antidiuretic, and hardly at all to oxytocic activities. However, even at 200 nM, the antipressor antagonists dPTyr(Me)AVP and d(CH2)5Tyr(Me)AVP had no effect on potentiation by AVP. The lack of antagonism was partly due to the agonistic effects of the antagonists on the pituitary gland, an effect not observed within vascular tissue. The results thus suggest that anterior pituitary vasopressin receptors resemble, but are not identical to, V1 (pressor and hepatic), do not resemble the V2 (renal), and might be classified as V3 (pituitary) receptors.
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PMID:A novel type of vasopressin receptor on anterior pituitary corticotrophs? 298 63

In addition to corticotropin-releasing factor (CRF) and structurally related peptides, arginine vasopressin (AVP), oxytocin, angiotensin II, vasoactive intestinal polypeptide, peptide histidine isoleucinamide, epinephrine (E), and norepinephrine induce secretion of adrenocorticotropin (ACTH) from corticotropic cells in vitro. The apparent affinity and intrinsic ACTH-releasing activity of these substances are lower than those of CRF. These substances can also act synergistically with CRF. In this paper the role of catecholamines and AVP in the control of ACTH release is discussed. Infusion i.v. of E increases plasma ACTH and corticosterone to levels that are normally found during stress. E-induced stimulation of pituitary-adrenal activity is mediated by beta adrenoceptors and involves release of CRF, because it can be prevented by beta-adrenoceptor blockers and by destruction of CRF neurons (hypothalamic lesions), blockade of CRF release (chlorpromazine, morphine, and Nembutal), or administration of CRF antiserum. Although stress can cause a vast increase in plasma E, circulating E is not essential for the acute stress-induced release of ACTH because blockade of beta (or alpha) adrenoceptors, administration of chlorisondamine, or extirpation of the adrenal medulla and sympathectomy do not prevent the pituitary-adrenal response to stress. In contrast, circulating E plays a major role in the release of intermediate-lobe peptides during emotional stress. Studies of the role of AVP in pituitary-adrenal control by the use of pressor receptor (V1) antagonists are not valuable because of the ineffectiveness of such antagonists in blocking AVP-induced release of ACTH from corticotropic cells in vitro. Treatment of rats with an antiserum to AVP reduces the ACTH response to stress. We conclude that AVP has an important role in stress-induced activation of the pituitary-adrenal system, possibly by potentiating the effects of CRF.
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PMID:Role of epinephrine and vasopressin in the control of the pituitary-adrenal response to stress. 298 37

Neuropeptides and biogenic amines known to be present in neurons or afferent terminals in the paraventricular nucleus (PVH), supraoptic nucleus (SON) and/or lateral hypothalamus (LH) were added to small areas of these structures obtained by micropuncture and cyclic adenosine monophosphate (cAMP) levels were measured. cAMP accumulation occurred in PVH, SON and LH in response to neuropeptides of the secretin family, such as vasoactive intestinal peptide (VIP) and in response to catecholamines. Bradykinin, alpha-melanocyte-stimulating (alpha-MSH), luteinizing hormone-releasing hormone (LH-RH), oxytocin and carbamylcholine stimulated cAMP accumulation selectively in one or two of the above structures. Glucagon, cholecystokinin (CCK), somatostatin (SRIF), corticotropin-releasing factor (CRF), thyrotropin-releasing hormone (TRH), adrenocorticotropin (ACTH), melanocyte-stimulating hormone (MSH), methionine enkephalin (Met-Enk), beta-endorphin, neurotensin, bombesin and angiotensin II did not effect cAMP levels while leucine enkephalin (Leu-Enk), arginine vasopressin and gamma-aminobutyric acid (GABA) elicited regionally selective decreases in basal levels of cAMP. When interactions between some of these compounds were measured, VIP and norepinephrine exerted a more than additive effect on cAMP elevation in the PVH, while the effect on cAMP of the SON and LH was additive.
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PMID:Interaction of neuropeptides and biogenic amines on cyclic adenosine monophosphate accumulation in hypothalamic nuclei. 300 57


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