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)

The ultrastructure and the spontaneous and drug-induced contractility of the testicular capsule of 18 boars were investigated. Isometric recordings were obtained in vitro using strips of the tunica albuginea isolated from various regions of the testis. Maximal contractile activity was found in the strips of the posterior border of the testis, in which the histological studies (light and electron microscopy) showed abundant typical smooth muscle cells distributed in layers parallel to the testicular long axis. These cells were largely aggregated in the inner layer of the testicular capsule, which displayed contractile activity similar to that of the entire tunica albuginea. The outer layer of the tunica albuginea was almost totally devoid of smooth muscle fibres and showed little or no contractility. The spontaneous contractions were rhythmic and exhibited an amplitude of 20--70 mg and a frequency of 5--30 contractions/10 min. Norepinephrine, acetylcholine and oxytocin all produced an increase of the contractility of the tunica albuginea, consisting mainly in a rise of the tone.
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PMID:Studies on the contractile activity and ultrastructure of the boar testicular capsule. 51 9

Electromyograms were obtained from three different locations on the uterus of conscious, unrestrained rats during the 4 day estrous cycle. Intrauterine pressure changes were monitored simultaneously by means of indwelling intraluminal balloons (vol. 0.02 to 0.05 ml.). Electrical activity consisted of bursts of action potentials that were usually initiated at either end of the uterus. Propagated burst activity gave rise to cyclic intrauterine pressure changes, whereas bursts appearing at one electrode only did not elicit any measurable contractions. The rate of intrauterine pressure development depended on the propagation velocity, whereas the tension achieved was related to the duration of burst activity. All three parameters of electrical activity studied, namely, the duration and frequency of spike bursts, as well as their rate of propagation, varied significantly during the cycle. Regional differences were also subject to cyclic variations; thus, in proestrus the bursts originated predominantly at the cervical end, whereas in diestrus they were usually initiated at the ovarian end. Oxytocin stimulated the frequency and duration of bursts along the whole uterus and elicited corresponding changes in intrauterine pressure. Response to oxytocin was dose dependent and modified by cycle stage. Norepinephrine caused a transient prolongation of burst activity that was not dose dependent; epinephrine had a marked dose-dependent inhibitory action. The response to catecholamines did not vary significantly during the cycle. The variations in electrical and mechanical activity were characteristic for each stage of the ovarian cycle and could be correlated with the well-known hormonal changes. High circulating estrogen levels in proestrus are associated with infrequent but rapidly propagated spike bursts, whereas low levels in estrus are associated with frequent and sometimes nonpropaged bursts. The rise in plasma estrogen in diestrus coincides with a decrease in the frequency of burst activity, and the elevated progesterone levels are probably causally related to the significant drop in propagation velocity and the increase in duration of bursts observed in diestrus. These findings are consistent with the concept that estrogen withdrawal activates the estrogen-primed, quiescent myometrium, and that progesterone has an effect similar to that of estrogen withdrawal--at least in the rat.
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PMID:Electrical and mechanical activity of rat uterus in vivo during the estrous cycle. 56 83

The effects of norepinephrine, phentalamine, oxytocin, vasopressin, several prostaglandins, and indomethacin on the spontaneous motility of isolated guinea pig cauda epididymidis were explored. Phentolamine and indomethacin reduced the isometric peak tension of spontaneous epididymal contractions. Phentolamine also depressed the frequency. Both findings suggest that catecholamines and endogenous prostaglandins are in some way regulators of the spontaneous motility of the cauda epididymidis. Norepinephrine resulted in the development of a distinct, sustained, tonic contraction without phasic activity, whereas prostaglandins E1, E2, and F2 alpha elicited a tonic increase accompanied by frequent, superimposed, phasic contractions. Both oxytocin and vasopressin comparably enhanced epididymal motility, producing contractile responses similar to those observed with prostaglandins. Since the epididymal contractions can influence the time spent by spermatozoa in passing through the ductus epididymidis, the above-mentioned compounds could play an important role in spermatozoal transport via modulation of epididymal contractile activity. In addition, such naturally occurring substances might regulate the release of sperm from the last portion of the epididymis into the ductus deferens.
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PMID:Physiologic and pharmacologic studies on the motility of isolated guinea pig cauda epididymidis. 80 41

The spontaneous motility of ovaries isolated from guinea pigs in early and late proestrus and estrus was explored. The influences of oxytocin, prostaglandin F2alpha (PGF2alpha), and adrenergic agonists and antagonists were also studied. Spontaneous ovarian isometric developed tension (IDT) and rate of contractions (RC) were greater in late proestrus than in early proestrus or estrus. Furthermore, in late proestrus, oxytocin and PGF2alpha induced ovarian motilities of comparable magnitude and significantly greater than those elicited in other stages of the cycle. Norepinephrine and phenylephrine either failed to alter or inhibited IDT and RC of ovaries in estrus, but stimulated motility in the presence of propranolol. The depressive influence of norephinephrine upon the IDT of ovaries in early proestrus was not seen in late proestrus, when the neurotransmitter was clearly stimulating. The hormonal status of guinea pigs seems to influence spontaneous ovarian motility as well as pharmacologic reactivity to several agents, including those presumably acting upon alpha- and beta-adrenergic receptors.
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PMID:Physiologic and pharmacologic studies on the motility of isolated guinea pig ovaries. 116 89

The importance of sympathetic innervation changed significantly during sexual maturation and in the course of the oestrous cycle in females. Basal secretion of progesterone is partly dependent on constant beta-adrenergic stimulation since local infusion of propranolol (beta-blocker) into the ovary decreased progesterone secretion by 20-30% of pre-treatment value. Noradrenaline given into the abdominal aorta in the moderate doses affected very quickly and dramatically the secretory function of the corpus luteum during the luteal phase in cattle and also in other species. Thus short-lasting mobilization stress protects and even supports corpus luteum function. This effect is exerted through the stimulation of beta-adrenoceptors which then activates specific intracellular enzymes. Additionally noradrenaline acts upon vascular alpha-receptors and increase ovarian blood flow allowing utilization of serum-derived lipoprotein as a source of cholesterol for steroidogenesis. The highest amount of specific beta-receptors in luteal membranes was found in the newly-formed corpus luteum which does appear to require noradrenergic support especially at that stage of its development. The mechanism of noradrenaline influence upon luteal cells resulting concomitant progesterone and ovarian oxytocin secretion is, however, obscure. It is suggested that intracellular second messengers (cAMP, Ca2+) involved in noradrenaline action can simultaneously affect the secretion of both these hormones and this indicates some functional relationship between them. The presented results are focused mainly upon cattle due to the importance of this species among other domestic animals. Nevertheless for comparison data from other species are also quoted.
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PMID:Role of the noradrenergic system in the secretory function of the corpus luteum. 134 65

Microdialysis sampling was used to measure the release of oxytocin (OXY) and monoamine and amino acid transmitters from the region of the medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BNST) during parturition and suckling in sheep. Results showed that OXY and gamma-aminobutyric acid release increased in both the MPOA and BNST during parturition and suckling. Noradrenaline (NA) release increased in both structures during parturition but not during suckling. Dopamine (DA) release increased in the MPOA and decreased in the BNST during both parturition and suckling. Aspartate release increased in the MPOA during parturition, and the BNST during suckling, and glutamate release increased in the MPOA and BNST at parturition and only in the BNST during suckling. No changes in the release of serotonin or taurine occurred in these structures during parturition or suckling. In a further experiment on 6 estrogen-primed sheep, OXY (10 micrograms/ml) was infused into the MPOA via bilaterally placed microdialysis probes. This treatment inhibited rejection behavior towards lambs, but did not activate positive maternal responses. These OXY infusions also stimulated release of NA. These results show that complex patterns of neurochemical release occur in two closely related areas of the brain, the BNST and MPOA, during parturition when maternal behavior is stimulated. However, while these patterns of release are similar in the two structures, particularly at birth when maternal behavior is stimulated, they are not identical during labor contractions and suckling. The release of oxytocin within the MPOA during parturition may be important for stimulating a reduction in aggression towards lambs, although this action might be mediated via the effect of OXY on NA release.
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PMID:Oxytocin, amino acid and monoamine release in the region of the medial preoptic area and bed nucleus of the stria terminalis of the sheep during parturition and suckling. 154 Aug 26

The substances stimulating the release of immunoreactive corticotropin-releasing factor from cultured human placental cells were investigated. Monolayer primary cultures of trophoblast cells from pregnant women at term were used. The immunoreactive corticotropin-releasing factor released in the culture medium eluted from high-performance liquid chromatography with the same retention time as human corticotropin-releasing factor. Norepinephrine and acetylcholine increased immunoreactive corticotropin-releasing factor release into the culture medium in a dose-related manner. Epinephrine was partially active, whereas dopamine and serotonin did not induce significant changes of immunoreactive corticotropin-releasing factor release from placental cultures. Angiotensin II, interleukin-1, oxytocin, and arginine-vasopressin also increased placental immunoreactive corticotropin-releasing factor release in a dose-related manner, whereas other peptides (vasoactive intestinal peptide, substance P, somatostatin, atrial natriuretic factor, interleukin-2) were ineffective. These results showed that several neurotransmitters and peptides stimulate the release of immunoreactive corticotropin-releasing factor from placental cells, suggesting their possible involvement in the physiologic regulation of placental immunoreactive corticotropin-releasing factor release during pregnancy and parturition.
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PMID:Neurotransmitters and peptides modulate the release of immunoreactive corticotropin-releasing factor from cultured human placental cells. 256 97

The mechanisms of lymphatic-vascular transfer across the ovarian vascular pedicle were studied in anaesthetized sheep 8-15 days after ovulation. [3H]Prostaglandin F2 alpha (PGF2 alpha), [14C]mannitol and [36Cl]Na were infused continuously into either a uterine lymphatic or a uterine vein and the kinetics of transfer into the adjacent utero-ovarian vein or ovarian plasma were studied. Transfer occurred according to the sequence [36Cl] greater than [14C] greater than [3H] indicating that PGF2 alpha is not transferred by rapid diffusion, as with [36Cl]Na, nor by a paracellular route, as with [14C]mannitol, but by a slower process probably involving facilitated diffusion. Transfer into the adjacent utero-ovarian vein or ovarian blood was greater when compounds were infused into a uterine lymphatic than into a uterine vein. Substantially more [3H]PGF2 alpha occurred in the adjacent corpus luteum than either of the other compounds after a lymphatic infusion. Intra-lymphatic infusion of PGF2 alpha stimulated the release of ovarian oxytocin but the effect was not confined to the adjacent ovary. Intravenous (jugular) infusion of PGF2 alpha failed to stimulate ovarian oxytocin secretion whereas close-arterial infusion into the ovaries was effective, and the possibility was investigated that any systemic effect of PGF2 alpha was mediated through neural mechanisms. Noradrenaline and acetylcholine were both effective in causing the release of ovarian oxytocin when infused close-arterially into the ovary. With infusions of acetylcholine, ovarian oxytocin secretion rate was increased over fivefold without any change in posterior pituitary release. Noradrenaline and acetylcholine produced a concomitant fall in ovarian blood flow, and neurotransmitter-induced ischaemia may have played a role in ovarian oxytocin release. The finding that PGF2 alpha infused into a uterine lymphatic stimulates ovarian secretion of oxytocin, and that the effect is bilateral whereas PGF2 alpha accumulation in ovarian tissue is unilateral, implies that its mechanism of action may not be solely directed at the luteal cell.
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PMID:Neurotransmitters and lymphatic-vascular transfer of prostaglandin F2 alpha stimulate ovarian oxytocin output in sheep. 276 49

Norepinephrine and the alpha-agonist phenylephrine in concentrations of 10(-5) to 10(-3) M prompted the release of radioimmunoassayable vasopressin (up to 150 pg/min) and oxytocin (up to 20 pg/min) from intraarterially perfused explants of rat basal forebrain. Drug effects were markedly reduced or abolished in the presence of the non-specific alpha-antagonists phentolamine and phenoxybenzamine, and the specific alpha 1-antagonist prazosin. In concert with recent in vivo and in vitro electrophysiological observations, these data imply that endogenous noradrenergic pathways to magnocellular neurosecretory cells are excitatory, mediated through activation of their alpha 1-receptors, thereby enhancing the release of both vasopressin and oxytocin in the neurohypophysis.
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PMID:Alpha 1-adrenergic receptor activation releases vasopressin and oxytocin from perfused rat hypothalamic explants. 301 17

The changes in plasma levels of arginine-vasopressin (AVP) and oxytocin (OXT) of rabbits by intraventricular administration of various drugs and their effects on the release of both hormones from the isolated posterior pituitary of rats were examined. An intraventricular injection of hypertonic saline, carbachol, angiotensin II, prostaglandin E2 or histamine to a rabbit increased the concentrations of plasma AVP and OXT, whereas serotonin decreased their plasma levels. Noradrenaline increased the concentration of OXT, but not that of AVP. Dopamine did not significantly affect the plasma level of either hormone. The release of AVP and OXT from the posterior pituitary fragments of rats was stimulated by changing the osmolality of the perfusion medium in vitro. Perfusion with medium containing dopamine suppressed the release of both hormones. However, the other bioactive amines and the drugs mentioned above did not affect the release of AVP and OXT.
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PMID:A study on the release mechanism of vasopressin and oxytocin. 323 19


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