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 present studies were designed to test, using a combination of in vivo and in vitro paradigms, the potency of angiotensin II (AII) to release ACTH, in relation to that of other neural peptides with corticotropin-releasing activity (CRA), such as synthetic corticotropin releasing factor (CRF), arginine vasopressin (AVP) and oxytocin (OXY); and to determine whether a central or peripheral locus is the primary site of action of the peptide. Injection of AII (1 and 5 micrograms, i.p.) in intact unanesthetized male rats, resulted in an increase in plasma ACTH and beta-endorphin-like immunoreactivity (beta-end-LI) levels after the largest dose. The responses, however, were not as pronounced as those elicited by 0.5 microgram of CRF or 1 micrograms of AVP. Injection of AII (i.v., 1 or 5 micrograms) in centrally blocked rats (pretreated with chlorpromazine-morphine-nembutal) failed to elicit any increase in either ACTH or bet a-end-LI levels, whereas 0.5 microgram of either CRF or AVP increased both hormones several fold. In vitro studies using dispersed anterior pituitary cells obtained from male donor rats showed that AII as well as AIII could increase ACTH release at doses of 10(-8) M or larger. Under the same conditions, CRF and AVP stimulated ACTH release to a greater degree at 10(-10) and 10(-9) M, respectively. On the other hand, OXY was stimulatory at 10(-8) M. Dose-response studies indicated a rank order of CRA as follows: CRF greater than AVP greater than OXY greater than AII = AIII. Both AII and AIII showed additive effects when coincubated with either CRF or AVP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Angiotensin II and ACTH release: site of action and potency relative to corticotropin releasing factor and vasopressin. 631 48

The present studies were designed to evaluate the binding characteristics of arginine vasopressin (AVP), using rat anterior pituitary dispersed cells, in correlation with the biological activity of the peptide. Synthetic AVP released ACTH from dispersed anterior pituitary cells in a concentration-dependent fashion, with a minimal effective dose of 10(-10) M. [3H] AVP, the ligand for binding studies, showed full biological activity at different concentrations. Saturable and high affinity binding sites for [3H]AVP were obtained using dispersed anterior pituitary cells. Specific binding reached equilibrium by 180 min at 22 C, and rapid and complete dissociation was obtained after the addition of excess AVP. Scatchard analysis of the data indicated a single class of binding sites, with an apparent Kd of 1.63 nM and a binding capacity (Bmax) of 10.7 fmol/10(6) cells, at 37 C. When cells were incubated at 22 C, Kd (7.63 nM) and Bmax (39 fmol/10(6) cells) values were within the same order of magnitude. AVP effectively inhibited [3H]AVP binding with an IC50 of 1.5 X 10(-7) M, while oxytocin showed a somewhat higher IC50 (0.9 X 10(-6) M) and did not achieve complete inhibition of binding. An AVP analog with a ring substitution ( Asu1 ,6 AVP) showed decreased displacement capacity. Both oxytocin and the AVP analog showed weak ACTH-releasing activity compared to synthetic AVP. This indicates that modifications in the tail and/or ring portion of the AVP molecule reduce both the binding affinity and ACTH-releasing activities of these peptides. Other structurally unrelated peptides with intrinsic ACTH-releasing activity, such as rat corticotropin-releasing factor and angiotensin II, had no affinity for AVP-binding sites. The results indicate that specific AVP-binding sites in anterior pituitary cells are closely correlated with the intrinsic ability of the peptide to elicit ACTH release.
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PMID:Arginine vasopressin and adrenocorticotropin release: correlation between binding characteristics and biological activity in anterior pituitary dispersed cells. 632 40

Comparative ultrastructural localization of corticotropin-releasing factor (CRF) and oxytocin was performed in the rat median eminence of Long Evans and Brattleboro rats. The peroxidase-antiperoxidase technique used on serial ultrathin sections revealed CRF and oxytocin neurosecretory granule colocalization in the same fibers of the internal layer running towards the posterior pituitary. It is probable that both these peptides coexist in the same granules. In the Brattleboro rats, while genetically lacking vasopressin, CRF was nevertheless shown to be present. In these rats, as was demonstrated in the Long Evans rats, CRF distribution paralleled that of oxytocin only in the internal zone of the median eminence.
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PMID:Comparative immunoelectron microscopic localization of corticotropin-releasing factor (CRF-41) and oxytocin in the rat median eminence. 633 45

A corticotropin-releasing factor (CRF), oxytocin and arginine-vasopressin were localized immunohistochemically in the paraventricular nucleus of colchicine-treated male rats. Small CRF-containing neurons were distributed in the parvocellular region. Some magnocellular neurons were also immuno-stained with anti-CRF serum, but after preabsorption of the antiserum with pure synthetic CRF, the staining of these magnocellular neurons was unaffected, which suggests that this CRF-positive reaction was non-specific. By comparing the distribution of CRF and oxytocin or vasopressin on serial 5 micron cryostat sections, it was revealed that CRF and oxytocin or CRF and vasopressin do not coexist in the same neuron.
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PMID:Immunohistochemical evidence against the coexistence of a corticotropin-releasing factor and oxytocin or vasopressin in the rat paraventricular nucleus. 633 30

A specific rabbit anti-CRF serum and the immunoperoxidase technique were used to show that CRF-containing neurons are mainly distributed in the paraventricular and supraoptic nuclei of the rat hypothalamus. In addition, immunoreactive neurons are scattered in other hypothalamic regions. These neurons are 20--30 micrometers in diameter. From the present and previous investigations it may be concluded that the hypothalamic magnocellular nuclei, i.e., paraventricular and supraoptic, and other hypothalamic accessory nuclei, are the producing sites not only for vasopressin and oxytocin, but also for corticotropin-releasing factor.
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PMID:Immunohistochemical identification of neurons containing corticotropin-releasing factor in the rat hypothalamus. 634 98

Conspicuous differences in the distributional pattern of nerve fibers containing corticotropin-releasing factor (CRF) or posterior lobe hormones, respectively, were shown in the median eminence of the adult male rat by means of immunoperoxidase histochemistry, with the use of anti-CRF, anti-oxytocin, and anti-vasopressin sera. In the rostral and central divisions of the median eminence, a high concentration of CRF-immunoreactive nerve fibers was found in the median portion of the external layer; these fibers terminated on the capillary loops of the hypophysial portal system. In the caudal division of the median eminence, the CRF-immunoreactive nerve fibers were located in the median to paramedian portions of the external layer. Numerous oxytocin- and vasopressin-immunoreactive nerve fibers were observed evenly distributed throughout the internal layer of the median eminence. In the external layer, a small number of the oxytocin- and vasopressin-containing nerve fibers was found around the capillary loops, particularly in the median to paramedian portions. The distributional patterns of the CRF and the posterior lobe hormones in the hypothalamo-hypophysial system and their functional interrelationship are discussed.
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PMID:Differences in the distributional pattern of CRF-, oxytocin-, and vasopressin-immunoreactive nerve fibers in the median eminence of the rat. 634 99

To clarify the anatomical organization that allows for the synergy of vasopressin and oxytocin with corticotropin-releasing factor (CRF) in promoting adrenocorticotropic hormone secretion from the anterior pituitary, immunohistochemical double staining methods were used to compare the distribution of these peptides in the hypothalamic paraventricular nucleus of normal, colchicine-treated, and adrenalectomized male rats. In untreated animals, a few CRF-stained cells were found in the parvocellular division of the paraventricular nucleus, while brightly stained oxytocin- and vasopressin-immunoreactive cells were centered in the magnocellular division. In animals treated with colchicine, and inhibitor of axonal transport, large numbers of CRF-stained cells were found in the parvocellular division of the nucleus, and 1-2% of these also stained with antivasopressin. As reported previously, a substantial number of oxytocin-stained cells, centered in a discrete anterior part of the magnocellular division, also expressed CRF immunoreactivity. In contrast, after adrenalectomy, CRF immunostaining of cells in the parvocellular division was enhanced selectively and greater than 70% of these cells also stained positively for vasopressin. The distribution of oxytocin-stained cells was not influenced by adrenalectomy. The unusual localization of vasopressin immunoreactivity in parvocellular neurosecretory neurons in the adrenalectomized rat suggests that a single population of cells can produce CRF and vasopressin, both of which are potent promoters of adrenocorticotropic hormone secretion. These findings indicate that there is a state-dependent plasticity in the expression of biologically active peptides by individual neuroendocrine neurons.
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PMID:Co-expression of corticotropin-releasing factor and vasopressin immunoreactivity in parvocellular neurosecretory neurons of the adrenalectomized rat. 636 32

Neural elements immunoreactive for ovine corticotropin releasing factor-like immunoreactivity (oCRF-LI) were shown to be present in the diencephalon of the pigeon by using peroxidase-antiperoxidase immunocytochemistry. The external zone of the anterior median eminence contains a rich network of varicose oCRF-LI fibers in close proximity to the pituitary portal capillaries. Perikarya reactive for oCRF-LI were found in several regions known to innervate the median eminence and gave rise to axons which joined the hypothalamo-hypophyseal tract. A close topographical relationship between neurophysin-containing and oCRF-LI-containing neurons was found in anterior periventricular regions. These observations suggest that oCRF-LI material might be involved in the hypothalmic control of anterior pituitary hormone secretion in birds, and that neurophysin- and oCRF-LI-producing nerve cells might be functionally coupled.
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PMID:Comparative localization of neurons containing ovine corticotropin releasing factor (CRF)-like and neurophysin-like immunoreactivity in the diencephalon of the pigeon (Columba livia domestica). 638 81

Using adjacent serial brain sections, a morphometric method has been developed for analysing the coexistence of the neurophysial hormones, vasopressin (VP) and oxytocin (OT), with their specific neurophysins (N). A significative correlation was found between the immunoreactive areas stained with (1) anti-VP and anti-N-VP sera, and between the immunoreactive areas detected with anti-OT and anti-N-OT antibodies. Besides, the immunoreactive areas stained with (1) anti-VP and anti-OT antibodies, (2) anti-N-OT and anti-VP antibodies, (3) anti-N-OT and anti-N-VP antibodies or (4) anti-OT and anti-N-VP antibodies were totally independent. A different method projecting the microscope images on a reference grid with a camera lucida permitted to quantify the coexistence of an ovine corticotropin-releasing factor-related-peptide (41-CRF) with OT in the paraventricular neurons of the Brattloro rat brain. In these animals, the same method applied after total hypophysectomy demonstrated that the neurons synthezising simultaneously 41-CRF and OT projected their axons to the neurohypophysis; the same operation increased the relative number of neurons containing 41-CRF only; it can be supposed that they originated the infundibular terminals.
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PMID:[The co-localization of neurohypophysis peptides and the corticotropin-releasing factor in the rat brain. Contribution of morphometric analyses]. 639 88

Reversed-phase, high-performance liquid chromatography (HPLC) was carried out to characterize rat hypothalamic corticotropin-releasing factor (CRF) using synthetic ovine CRF as a marker. Samples were injected onto a stainless steel column (4 X 250 mm) packed with Hitachi gel 3053. The column was eluted using a gradient elution of increasing acetonitrile concentration, in a mixture of NaCl-HCl at a flow rate of 1.0 ml/min, monitoring the column effluent at 220 nm with an UV detector. Fractions eluted every 1-2 min were collected and lyophilized for subsequent CRF bioassay and radioimmunoassay. When various neuropeptide mixtures including synthetic ovine CRF were injected onto the column, synthetic ovine CRF was separated from the other neuropeptides with a gradient of 0-60% acetonitrile in 0.1 M NaCl-0.01 N HCl or 0-08% acetonitrile in 0.05 M NaCl-0.01 N HCl. The median eminence extracts showed two main peaks of CRF bioactivity on HPLC. One (small CRF) coeluted with arginine vasopressin and oxytocin markers, and the other (big CRF) appeared near the position of synthetic CRF and was divided into two peaks. One coeluted with synthetic ovine CRF and the second eluted after synthetic CRF, showing high CRF activity. Three or four peaks of CRF immunoreactivity appeared on HPLC and the main peak appeared after synthetic ovine CRF marker. Our results suggest that rat CRF is different from ovine CRF, and the total lipophilicity of amino acid residues of rat CRF may be higher than that of ovine CRF.
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PMID:Characterization of rat hypothalamic corticotropin-releasing factor by reversed-phase, high-performance liquid chromatography with synthetic ovine corticotropin-releasing factor as a marker. 660 51


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