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)

To investigate the mechanism of ovulation in the hen, histological and physiological investigations on the contractility of the follicular wall were carried out. Smooth muscle bundles in the loose connective tissue coat from the stalk to the equator showed spontaneous rhythmic contractions with an alternation of contraction and pausing periods of about 4 min. The administration of prostaglandins F2 alpha (PGF2 alpha), E2 (PGE2), ovarian oviposition inducing factor (OOIF), oxytocin and acetylcholine increased the frequency and amplitude of the contractions. The theca layer showed spontaneous contractions at a frequency of about 30 per 10 min. PGF2 alpha, OOIF, acetylcholine, adrenaline and noradrenaline induced tonic contractions, whereas PGE2, oxytocin and histamine induced relaxation. It is suggested that the contraction of the follicular wall promotes the rupture of the stigma at ovulation and the neurotransmitters as well as prostaglandins and OOIF may be involved in this event.
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PMID:Studies on the contractility of follicular wall with special reference to the mechanism of ovulation in hens. 613 16

The above procedures clearly demonstrate the effectiveness of the fluorescence histochemical and immunohistochemical methods in analysis of central CA neuron systems. Each method is well characterized and possesses sufficient versatility to permit a variety of experimental applications. The fluorescence histochemical technique is extremely reliable, produces good cell and fiber morphology, and has served as the fundamental procedure used to define the organization and distribution of CA-containing neurons throughout both the central and peripheral nervous system. However, the basic method makes no distinction between individual catecholamine neuron systems unless combined with mechanical or chemically induced lesions. The immunohistochemical technique relies upon the availability of antisera generated against the catecholamine-synthesizing enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase(DBH), and phenylethanolamine N-methyltransferase (PNMT). Each of these enzymes catalyzes different steps in catecholamine metabolism and therefore can be used in conjunction with one another to selectively delineate the organization and distribution of neuronal cells and processes containing dopamine (TH), noradrenaline (TH and DBH), and adrenaline (PNMT). In addition, the immunohistochemical method may be coupled with the fluorescence histochemical technique, dual-labeling immunohistochemical methods, and retrograde tract tracing methods to provide further information on the interrelations of individual CA systems with one another and other chemically distinct systems of neurons. The usefulness of the immunohistochemical method in elucidating the organization of separate systems of CA-containing neurons is illustrated in a recent study by Swanson and collaborators. Utilizing antisera raised against the previously mentioned CA synthesizing enzymes, they analyzed the organization of CA systems within the paraventricular and supraoptic nuclei of the hypothalamus. By combining this analysis with immunohistochemical staining with antisera generated against vasopressin and oxytocin, they were able to demonstrate differential distribution of adrenergic and noradrenergic fibers within each nucleus which could be correlated with the distribution of vasopressin-containing neurons. In addition, through the combined use of immunofluorescence and retrograde transport of the tracer dye true blue, they were able to show that a small percentage of TH-containing neurons within the paraventricular nucleus project to the region of the dorsal motor vagal complex and/or thoracic levels of the spinal cord. Although the later finding relied upon fluorescence microscopy, Bowker a
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PMID:Neurotransmitter histochemistry: comparison of fluorescence and immunohistochemical methods. 614 2

The effects of chlorbutol (0.7, 1.4 and 2.8 mM) on the contractile responses induced by KCl and noradrenaline (NA) and on 45Ca movements have been studied on rat isolated thoracic aorta. Chlorbutol decreased, in a dose-dependent manner, contractions induced by KCl and NA and this effect was observed whether it was added before or after the induced contractions. Preincubation with chlorbutol inhibited the contractile responses elicited by addition of Ca (1-5 mM) to Ca-free high-potassium solution. It also inhibited in a dose-dependent manner the 45Ca influx but increased 45Ca efflux in rat aortic strips. These results suggest that chlorbutol decreases peripheral resistance by reducing the availability of intracellular Ca to the contractile machinery in vascular smooth muscle cells. The effects of synthetic oxytocin (Syntocinon) at concentrations containing the same chlorbutol concentration were quantitatively similar from those produced by chlorbutol alone. Therefore, the inhibitory cardiovascular effects ascribed previously to synthetic oxytocin may be attributed to its preservative, chlorbutol, and not to oxytocin itself.
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PMID:Effects of chlorbutol on 45Ca movements and contractile responses of rat aorta and its relevance to the actions of Syntocinon. 614 94

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

Newborn rats were treated once with 2 Units of vasopressin (VP) or oxytocin, respectively. At the age of 2 months and 1 year, respectively, the reactivity of isolated aortic strips to vasopressin and noradrenaline was tested. In young adults animals vasopressin pretreatment enhanced whilst oxytocin pretreatment decreased the responsiveness of aortic strips to VP. In elder specimens both types of pretreatment resulted in an increased late sensitivity to VP. The norepinephrine-sensitivity was higher in the young adults pretreated with oxytocin, whilst in the elder ones vasopressin-retreatment gave the same late effect. It could be established that the hormone excess produced in the neonatal age led to the "amplification" of hormone receptors and this alteration provided to be permanent. A compound which is similar to but not identical with the hormone--in our case, oxytocin--would elicit an alteration of a less unindirectional and permanent type; late sensitivity changes in both directions may occur.
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PMID:Amplification of hormone receptors by neonatal oxytocin and vasopressin treatment. 624 17

Rhythmic motility of teats in lactating cows in vivo was studied by an improved plethysmographic technique. Oxytocin was infused intravenously and drugs were injected into the artery of the filled udder. The beta-adrenergic agent, isoprenaline, induced relaxation of the teats whereas the alpha-adrenergic agents phenylephrine and noradrenaline, elicited contraction. In one animal however, noradrenaline always exerted a biphasic effect. Pre-treatment with propranolol, a beta-adrenergic blocking agent, changed the biphasic effect into a purely activating response. Adrenaline, which exhibits both alpha and beta effects, induced relaxation, but after propranolol treatment relaxation was abolished and even converted into contraction of the teat. It seems clear that both alpha and beta adrenoceptors are present in longitudinal smooth muscles of the teats. Milk losses as intermittent spurts were observed in several cows. Spurts occurred synchronously with rhythmical teat motility in the filled udder during oxytocin infusion. The intensity of milk leakage was increased by isoprenaline and inhibited by noradrenaline, indicating the presence of alpha and beta receptors in teat sphincter muscles. Starting and stopping of milk spurts in correlation with rhythmical teat contractions were studied by audiovisual synchronization of video recording tape. The most common type of spurt began near the middle of the teat's relaxation phase and ended either just before or exactly at the beginning of the contraction phase. Interruption of the spurt is primarily due to closure of the streak canal.
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PMID:Studies on the motility of smooth muscles of the teats in lactating cows. 625 18

The arterial blood flow distribution between tumour and intact renal tissue was investigated in rats with transplanted sarcomas. Changes in tissue flow were measured by the microsphere tracer technique, and the redistributing effects on blood flow of vasopressin, noradrenalin and oxytocin was recorded. Bolus injections of vasopressin gave a transient decrease of intact tissue flow, not found in tumours. At increasing doses of vasopressin and in early tumour growth phase, the flow discriminating effect tended to vanish. Constant intravenous infusion of vasopressin gave similar reduction of flow in tumour and intact tissue. Selective administration into the renal artery reduced flow in intact tissue but produced ambiguous effects in tumour tissue. Noradrenalin produced less reduction of tumour flow as compared with intact tissue flow. Oxytocin increased tumour blood flow while no flow change occurred in intact tissue. Oxytocin thus appeared to produce the most favourable redistribution of flow within tumour kidneys for the prospect of conveying cytotoxic agents selectively to the tumour.
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PMID:Effects of vasopressin, noradrenalin and oxytocin on blood flow distribution in rat kidney with neoplasm. 627 54

Various lines of evidence have suggested that astrocytes play a dynamic role in control of hormone synthesis and release from the CNS. The model system most studied has been the rat hypothalamo-neurohypophysial system, consisting chiefly of the supraoptic and paraventricular nuclei and their axonal terminals. Neurons of this system manufacture and secrete oxytocin and vasopressin. Electron microscopic studies have shown that certain physiological conditions (e.g., dehydration, lactation) produce increases in direct apposition among these neurosecretory cells, an effect due to withdrawal of glial processes from between the neurons. Neurohypophysial astrocytes (pituicytes) show dynamic interactions with the neurons at the level of the terminals, by engulfing them and interposing processes between the terminals and the basement membrane when hormone demand is low. Pituicyte processes retract from both areas when hormone demand is high, allowing the neuronal terminals direct access to the perivascular space. Recently, osmotic manipulations (in the physiological range) have shown that these changes can be produced in vitro in neurohypophysial explants without stimulated hormone release. Experiments on cultured adult rat pituicytes have revealed similar morphological changes in response to noradrenaline. These changes were reversed or blocked by propranolol. The increase in direct soma-somatic apposition (7-9 nm separation) of magnocellular neurons could produce a tonic rise in (K+)o which would increase protein synthesis and contribute to the raised excitability of these neurons. Also, the removal of interposed glia could allow the formation of gap junctions and specialised synapses which are known to occur between these neurons. These in turn may participate in producing the coordinated firing that maximizes hormone release. The interactions of pituicytes with the terminals in the neurohypophysis suggests that these astrocytes are also a part of the mechanism of control of hormone release.
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PMID:Dynamic neuronal-glial interactions in hypothalamus and pituitary: implications for control of hormone synthesis and release. 638 46

The effect of SKF 525A (20 mg/kg i.v.) on pressor responses of various origin was studied. SKF 525A abolished or markedly reduced the pressor responses to ganglionic stimulants (DMPP and McN-A-343), but potentiated those to noradrenaline (in normal and pithed animals), adrenaline, tyramine, oxytocin and carotid occlusion. After recovery of the pressor effect of McN-A-343 from the SKF 525A-induced suppression, the pressor effect of noradrenaline was still further enhanced. The abolition of the pressor responses to ganglionic stimulants is due to the ganglion and adrenal-medullary blocking action of SKF 525A. This action of SKF 525A is of secondary importance for its potentiating effect. It is tentatively suggested that for the SKF 525A-induced potentiation a partial depolarization of arterial smooth muscle membrane resulting from a prolonged release of subthreshold concentrations of catecholamines from tissue stores, may be of primary importance.
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PMID:Potentiation by SKF 525A of the pressor responses to catecholamines, oxytocin and carotid occlusion in rats. 646 7

The distribution of dopamine (DA)-containing fibers in the virtual absence of noradrenaline (NA)-containing ones has been mapped by aldehyde fluorescence histochemistry in rats subjected to a combined neurotoxin treatment (intracerebral 6-hydroxydopamine injections plus systemic injections of the selective NA neurotoxin DSP-4). This pretreatment left di- and telencephalic DA levels largely unaffected, but reduced the NA levels by at least 86-96%. The resulting DA:NA ratios suggested that the catecholamine-containing structures, demonstrable by fluorescence histochemistry in the di- and telencephalic regions, were predominantly the DA-containing ones. While the distribution of DA terminal systems in the neo- and allocortical regions conformed well to previous results, the combined neurotoxin treatment revealed new features of the distribution of DA fibers in the diencephalon. In addition to the previously described innervations of the tubero-hypophyseal system, the incerto-hypothalamic system, and the mesohabenular pathway, previously unknown innervations were revealed in the supraoptic, paraventricular and dorsomedial nuclei of the hypothalamus, and in the paraventricular nucleus of the thalamus. Apart from some scattered fibers in the periventricular and lateral hypothalamic areas and medical zona incerta, other diencephalic nuclei seemed to be devoid of any significant DA terminal networks. The dopaminergic nature of these innervations is supported by DA uptake experiments (evaluated by fluorescence histochemistry) as well as by independent biochemical and immunohistochemical evidence. It is suggested that the DA innervations of the hypothalamic neurosecretory nuclei originate in cell bodies of the diencephalic A11-A14 cell groups and that such intradiencephalic DA projections participate in the regulation of oxytocin and vasopressin release from the pituitary.
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PMID:Selective histochemical demonstration of dopamine terminal systems in rat di- and telencephalon: new evidence for dopaminergic innervation of hypothalamic neurosecretory nuclei. 646 73


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