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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Noradrenaline (NA) (1-100 microM) was applied to 41 neurons recorded intracellularly from the supraoptic nucleus (SON) of the rat hypothalamic slice preparation; 34 (83%) neurons showed membrane depolarization which was dose-dependent. The depolarization was frequently accompanied by decreased membrane resistance, increased firing rate and increased fluctuations in membrane potential. Following the application of the alpha-agonist, phenylephrine, 10 out of 11 neurons tested showed similar responses, while the beta-agonist, isoproterenol, caused no changes in 6 out of 7 SON cells. We found no difference in responsiveness between neurons having a 'phasic' or a 'non-phasic' pattern of firing. We conclude that NA depolarized and increased the firing rate of both vasopressin- and oxytocin-containing neurons through an action on alpha-adrenergic receptors.
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PMID:Depolarizing effect of noradrenaline on neurons of the rat supraoptic nucleus in vitro. 356 13

The frog urinary bladder undergoes, in some conditions, a marked increase of its water permeability when incubated in hypertonic media. This increase was observed with various nonpermeant solutes. It seems to result from the shrinkage of an osmo-sensitive compartment of the tissue, probably the epithelial cells. Many similarities were found between this effect and the physiological increase in water permeability (hydrosmotic response) elicited by antidiuretic hormone (ADH): both were dependent on the physiological state of the animals, and although the response was slower after hyperosmolar than after hormonal challenge, the patterns of response were similar, and in both cases markedly dependent on bathing solution temperature. Norepinephrine and prostaglandin E(1), which in this tissue reduce the hydrosmotic action of ADH, presumably by inhibiting the adenyl cylase also reduced the effect of hyperosmolarity. Conversely this effect was potentiated by incubation in the presence of oxytocin, exogenous cyclic AMP, and theophylline, conditions in which the intracellular concentration of cyclic AMP is increased. These data demonstrate that the response to hyperosmolarity is elicited, at least partly, by mechanisms also involved in the physiological hydrosmotic response to ADH.
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PMID:The effect of hypertonic media on water permeability of frog urinary bladder. Inhibition by catecholamines and prostaglandin E 1 . 434 37

Extracellular application of some peptides (oxytocin, Lys-vasopressin, Leu-enkephalin) to neuron RPal induced pacemaker potentials generation and initiated or increased bursting activity. Norepinephrine and prostaglandins E1 and E2 effects on neuron RPal electric activity were qualitatively similar to those produced by oxytocin and Lys-vasopressin. Dibutyryl-cAMP, papaverine (phosphodiesterase inhibitor) and sodium fluoride (nonspecific adenylate cyclase activator) induced or potentiated bursting activity. It is supposed that oxytocin, Lys-vasopressin, Leu-enkephalin, norepinephrine and E group prostaglandins effects are mediated by intracellular processes related to activation of adenylate cyclase and increase of cAMP level in the neuron.
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PMID:[Reactions of an identified edible snail neuron to application of peptides, mediators, prostaglandins, and cyclic nucleotides]. 611 55

The effects of Pro-Leu-GlyNH2 (PLG), administered i.c.v. in doses of 3.5, 35, 350 and 3500 pmol, were studied on the alpha-MPT-induced disappearance of catecholamines in microdissected rat brain nuclei. PLG, dose-dependently, increased dopamine disappearance in the nucleus caudatus and globus pallidus, whereas a decrease in dopamine disappearance was observed in the nucleus dorsomedialis. Noradrenaline disappearance was decreased in the medial septal nucleus, anterior hypothalamic area and lateral amygdala. A tendency towards an increase in noradrenaline disappearance was observed in the nucl. supraopticus. These data show that PLG has a central site of action. The effects of PLG on dopamine disappearance are comparable to those previously found with vasopressin, while the effects of PLG on noradrenaline utilization show a striking similarity with those previously obtained with oxytocin.
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PMID:Pro-Leu-GlyNH2 affects dopamine and noradrenaline utilization in rat limbic-forebrain nuclei. 615 Jul 49

The effects of exogenous noradrenaline on the milk-ejection response were determined for nine Holstein cows. Noradrenaline was injected (0.95 nmol/kg) 15 s after the start of teat stimulation (preparation) or infused (0.13 nmol/kg per min, after bolus injection of 0.47 nmol/kg) starting 10 min before milking for 20 min. Cows were prepared (udder wash and dry) for 1 min before milking. Both injection and infusion resulted in approximately a 3.5-fold increase in peripheral noradrenaline at 1.75 min after the start of milking (baseline noradrenaline 0.83 and 0.89 nmol/l plasma; at 4 min, 2.00 and 3.00 nmol/l). Prolactin release was delayed and oxytocin release enhanced, while milk yield was decreased by 8.6% for both treatments. The maximum rate of milk flow was also depressed by treatment. In contrast, milking time increased for injection and decreased for infusion. In addition, a milk-yield-dependent change in the pattern of milk flow was seen in response to treatment. In medium-yield animals, two distinct milk-flow peaks were apparent and injection delayed the time to the second peak. We conclude that physiologically meaningful increases in peripheral noradrenaline can inhibit milk-ejection response by means of a peripheral mechanism not involving inhibition of release of oxytocin.
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PMID:Small increases in peripheral noradrenaline inhibit the milk-ejection response by means of a peripheral mechanism. 669 36

In vivo microdialysis and retrodialysis were used to investigate the role of oxytocin (OXY) release in the mediobasal hypothalamus (MBH) of the ewe in the control of sexual receptivity. Initial experiments showed that OXY release was significantly increased in ovariectomized animals treated with progesterone and oestradiol when they were sexually receptive towards males and received intromissions. No such increases were seen during tests where the ewes were receptive but the males were prevented from achieving intromission. By contrast, OXY release was significantly reduced in tests where the ewes were not receptive to the male. In a second experiment artificial vaginocervical stimulation (VCS) was found to significantly increase OXY release when the animals were treated with oestradiol and this effect was potentiated by progesterone priming. OXY release in the MBH was not significantly altered by VCS in the presence of progesterone priming alone. Plasma OXY concentrations were significantly increased by VCS following all three hormone treatments but no one treatment was significantly more effective than another. Noradrenaline release in the MBH was only significantly increased following VCS when progesterone priming was given before oestradiol treatment. No effects of VCS on release of GABA, glutamate or dopamine were seen but their basal concentrations were significantly increased by the combined steroid treatment compared to oestradiol alone. In a third experiment it was found that OXY (10 microM) infused bilaterally into the MBH of receptive ewes, by retrodialysis, significantly decreased sexual receptivity and increased the release of noradrenaline and GABA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of oxytocin release in the mediobasal hypothalamus of the sheep in relation to female sexual receptivity. 809 40

It was found previously that the reduction of ovarian oxytocin (OT) content by up to 80% on d 12 and 16 of the cycle affects neither luteolysis nor estrous cycle duration in cattle. Because ovarian OT is suggested to be involved in progesterone synthesis/secretion, in the present study we wanted to investigate whether ovary depletion of OT in the early stages of the estrous cycle will influence the corpus luteum (CL) secretory function. In experiment 1, heifers (n = 15) had cannulae inserted into the aorta abdominalis through the coccygeal artery. The tip of each cannula was placed cranial to the origin of the ovarian artery. Noradrenaline (NA; 4 mg) was infused on d 5-10 for 30 min daily, evoking release of OT and lower, but evident, increases in the progesterone levels. This did not affect the length of the estrous cycle compared with control heifers infused with saline only. Because ovarian OT cannot be restored once discharged, NA served as a tool to deplete the CL of OT in experiment 2. The same dose of NA was given on d 5-10 to 4 heifers. The corpora lutea used to determine OT tissue concentrations were obtained by surgery under local anaesthesia 10-15 min after the last NA infusion. This dose of NA, depleted CL of OT by about 51% compared with control heifers. We conclude that significant reduction of ovarian OT content on d 5-10 does not affect the CL function. Thus, if ovarian OT is involved in ovarian steroidogenesis, it plays a modulatory rather than a mandatory role.
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PMID:Reduction of ovarian oxytocin content from early luteal phase does not affect the corpus luteum secretory function in cattle. 817 17

Noradrenaline stimulates the concomitant release of ovarian oxytocin and progesterone in cattle within a few minutes, but the mechanism of its action is unknown. Changes in alpha- and beta-receptors and blood pressure were considered as possible mechanisms of the noradrenaline effect. Heifers in group 1 (n = 4) were infused with noradrenaline (0.16 microgram kg-1 min-1) for 30 min into the aorta abdominalis (cranial to the origin of the ovarian artery) on day 10. On days 11 and 12 before noradrenaline, phentolamine (alpha-blocker; 30 micrograms kg-1 min-1) or propranolol (beta-blocker; 5 micrograms kg-1 min-1) were infused for 30 min. Four other heifers were infused with noradrenaline only as controls. Only propranolol inhibited the stimulatory effect of noradrenaline on the secretion of progesterone and oxytocin. In group 2, heifers (n = 4) were infused, making use of the latin square design, with vasoconstrictive (angiotensin; 0.042 microgram kg-1 min-1) or vasodilatory (xanthinol-theophylline nicotinate; 250 micrograms kg-1 min-1) drugs that do not act through the adrenoceptors. Noradrenaline (0.3 microgram kg-1 min-1) was given 1 h later as in group 1. Blood pressure changes were measured in the posterior aorta abdominalis and oxytocin and progesterone concentrations were determined in the blood samples collected from the jugular vein. Noradrenaline and angiotensin increased (P < 0.01), whereas xanthinol decreased (P < 0.01), blood pressure during their infusion. However, the rise of oxytocin and progesterone concentrations was observed only after noradrenaline infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of noradrenaline influence on the secretion of ovarian oxytocin and progesterone in conscious cattle. 838 56

Mature heifers (n = 31) were infused with either saline or noradrenaline (0.3 microgram kg-1 min-1) via a cannula inserted into the aorta abdominalis through the coccygeal artery (cranial to the origin of the ovarian artery). Noradrenaline was infused for three periods of 30 min on days 11 and 12 and on days 15 and 16 of the oestrous cycle. After the noradrenaline treatment, saline was given for 1 h in the same way. During each infusion, peripheral blood samples were collected for progesterone and oxytocin determination every 5-10 min and then once a day until oestrus. As a control, four heifers were infused with saline in latin square design on days 11, 12 and on days 15, 16; they were bled once a day until oestrus. Other heifers were infused on the same days, but 1 h after the last infusion of noradrenaline, 500 micrograms of prostaglandin F2 alpha (PGF2 alpha) analogue was injected, to measure any remaining luteal oxytocin. For comparison four heifers were injected with PGF2 alpha analogue alone on day 12 and four others on day 16. Blood samples were taken as described previously. Each infusion of noradrenaline stimulated (P < 0.01) progesterone secretion. There was a significant (P < 0.05) response of oxytocin to each noradrenaline stimulation on days 11 and 12, although on each day the response to the second infusion was reduced and further reduced after the third infusion. On days 15 and 16, only the first noradrenaline infusion caused a clear surge of oxytocin with much smaller increases in oxytocin secretion after subsequent infusions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of oxytocin removal from the corpus luteum on secretory function and duration of the oestrous cycle in cattle. 850 12

Oxytocin (OT) release within the brain is thought to play a major role in inducing maternal behaviour in a number of mammalian species but little is known about the sites of release which are important in this respect. We have investigated whether the paraventricular nucleus of the hypothalamus (PVN) is a site of OT action on maternal behaviour in the sheep. In vivo microdialysis and retrodialysis was used to determine whether OT is released in the region of the PVN during the post-partum induction of maternal behaviour and if its release at this site can stimulate maternal behaviour in non-pregnant animals. In vivo sampling showed that OT concentrations increased significantly in the region of PVN at birth. When OT was retrodialysed bilaterally into the PVN (1 or 10 microM) of multiparous ewes treated with progesterone and oestradiol to stimulate lactation, maternal behaviour was induced in a significant number of animals (1 microM, 6/8 and 10 microM, 5/8) compared with controls (0/8 ewes). Similar infusions of the ring structure of OT, tocinoic acid (TOC-10 microM), also induced maternal behaviour in a significant proportion of animals (5/6 ewes) as did intracerebroventricular (ICV) OT (6/8 ewes) and artificial stimulation of the vagina and cervix (VCS, 8/9 ewes). On the other hand, vasopressin (AVP) 1 microM did not induce maternal behaviour in any ewes and a 10 microM dose only induced it in 2/8 animals. The neurochemical changes accompanying the above treatments were also investigated. Noradrenaline concentrations increased in the PVN after the retrodialysis administration of OT 1 microM and 10 microM, TOC 10 microM and AVP 1 microM, OT ICV and VCS. Dopamine concentrations were also increased by OT 10 microM, TOC 10 microM, AVP 1microM and OT ICV. Aspartate and glutamate concentrations were significantly reduced by retrodialysis infusions of OT 1 microM and AVP 1 and 10 microM but not by any other treatment. Finally, the retrodialysis infusion of OT and TOC, as well as ICV OT, significantly increased plasma OT release whereas AVP infusions did not. These results provide evidence that OT is released in the PVN during parturition and is important for the induction of maternal behaviour. It seems probable that OT release at this site has a positive feedback effect on both parvocellular and magnocellular OT neurons to facilitate co-ordinated OT release both in central OT terminal regions (to facilitate maternal behaviour) and peripherally into the blood (to facilitate uterine contractions/milk let down). The potential functional roles for the actions of OT on monoamine and amino acid transmitter release in the PVN are discussed.
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PMID:The role of oxytocin release in the paraventricular nucleus in the control of maternal behaviour in the sheep. 873 Jun 50


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