Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The corticotropin-releasing hormone (CRH) neurosecretory system in normal rats consists of two major subpopulations of parvicellular neurons in the hypothalamic paraventricular nucleus distinguished by the presence or absence of coexistent vasopressin precursor (pro-AVP)-derived peptides. These neurons project to the external zone of the median eminence, where the two subtypes of axons (CRH +/AVP + and CRH+/AVP-) were previously found to be approximately equal in number. The present study was undertaken 1) to determine whether the relative numbers of pro-AVP expressing and pro-AVP deficient perikarya in the paraventricular nucleus corresponded to what we previously found for the axons in the median eminence, 2) to map the two cell types throughout the entire paraventricular nucleus to determine whether significant differences existed in their distributions, and 3) to ascertain whether or not the pro-AVP deficient subpopulation expressed pro-AVP after adrenalectomy. Postembedding electron microscopic immunocytochemistry on serial ultrathin sections was used to identify the peptide phenotypes of perikarya in the paraventricular nucleus in normal rats and 7 days after adrenalectomy with and without colchicine treatment. The peptide phenotypes of neuronal perikarya in the paraventricular nucleus were identified by using antibodies to CRH, AVP, neurophysin (NP), the C-terminal glycopeptide of pro-AVP (GP), and oxytocin-associated neurophysin (NPOT). Groups of three serial coronal ultrathin sections were analyzed at 200-micron intervals throughout the entire rostrocaudal extent of the paraventricular nucleus. The sections in each group were stained for CRH, a pro-AVP-derived peptide (AVP, NP, or GP), and NPOT, respectively. Parvicellular CRH neurons were defined as CRH-positive cells, approximately 10 micron in diameter, that did not contain detectable NPOT. Pro-AVP expressing cells were defined as staining positively for AVP, GP, or NP and negatively for NPOT. Approximately equal numbers of pro-AVP expressing ("NPAVP+") and pro-AVP deficient ("NPAVP-") parvicellular CRH neurons were found within the paraventricular nucleus of colchicine-treated normal rats, and the two subtypes were distributed differently within the paraventricular nucleus. Although the pro-AVP expressing CRH cells stained intensely for NP and GP, staining for AVP was quite variable and difficult to quantify in colchicine-treated normal animals.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Distributions of pro-vasopressin expressing and pro-vasopressin deficient CRH neurons in the paraventricular hypothalamic nucleus of colchicine-treated normal and adrenalectomized rats. 326 32

Release of vasopressin (AVP) and oxytocin (OT) from rat median eminence and posterior pituitary tissue was studied in vitro by incubation in Krebs-56 mM KCl buffer. Both total tissue content and releasable pool of each hormone was measured in control rats, adrenalectomized rats and dexamethasone-treated rats. Adrenalectomy resulted in significantly increased release of AVP, but not OT, from median eminence tissue, whereas dexamethasone treatment failed to affect release of either hormone. Neither treatment had any effect on AVP or OT release from posterior pituitary tissue. Similarly, neither treatment caused any significant changes in total median eminence or posterior pituitary AVP and OT contents relative to controls, although dexamethasone-treated rats had a significantly lower posterior pituitary OT content than adrenalectomized rats. KCl-stimulated hormone release from median eminence tissue most likely represents an estimate of AVP and OT in zona externa terminals rather than in zona interna axons, because release was blocked by CoCl2 indicating calcium-dependent exocytosis. Immunohistochemical staining of median eminence tissue correlated well with the results of in vitro hormone release, in that increased AVP staining in the zona externa of adrenalectomized rats was also the only significant change noted using this methodology. Since increased levels of releasable AVP in the median eminence probably reflects similarly increased AVP levels in the hypothalamo-hypophyseal portal vessels of adrenalectomized rats, these results support a potential physiologic role for median eminence AVP, but not OT, in the chronic stimulation of adrenocorticotropin hormone secretion following adrenalectomy.
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PMID:In vitro release of vasopressin and oxytocin from rat median eminence tissue. 370 65

The effect of vasopressin released during Finnish sauna on blood pressure, heart rate and skin blood flow was investigated in 12 healthy volunteers. Exposure to the hot air decrease body weight by 0.6 to 1.25 kg (mean = 0.8 kg, P less than 0.001). One hour after the end of the sauna sessions, plasma vasopressin was higher (1.7 +/- 0.2 pg/ml, P less than 0.01 mean +/- SEM) than before the sauna (1.0 +/- 0.1 pg/ml). No simultaneous change in plasma osmolality, plasma renin activity, plasma norepinephrine, epinephrine, cortisol, aldosterone, beta-endorphin and metenkephalin levels was observed. Despite the slight sauna-induced elevation in circulating vasopressin, intravenous injection of the specific vascular vasopressin antagonist d(CH2)5Tyr(Me)AVP (5 micrograms/kg) 1 h after the sauna had no effect on blood pressure, heart rate or skin blood flow. These data suggest that vasopressin released into the circulation during a sauna session reaches concentrations which are not high enough to interfere directly with vascular tone.
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PMID:Haemodynamic role of vasopressin released during Finnish sauna. 375 60

Oxytocin (OT), vasopressin (AVP), and corticotropin (ACTH) levels were measured in peripheral plasma of male rats subjected to one of three models of stress: restraint, cold, or ether. ACTH secretion was increased in all three groups compared to unstressed controls. OT secretion was increased in rats subjected to restraint or ether but not cold. AVP secretion was increased only by ether stress. The data suggest that the hypothalamic and neurohypophysial contribution to the control of ACTH secretion may vary in response to different types of stress.
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PMID:Dissociation of oxytocin, vasopressin and corticotropin secretion during different types of stress. 608 65

The pituitary mechanism of the central inhibitory effect of PGE2 on gastric secretion was investigated in rats. The intravenous (i.v.) injection of neurointermediate lobe extracts but not of anterior lobe extracts inhibited gastric secretion in pylorus-ligated rats. The i.c.v. administration of 3 micrograms of PGE2 increased the plasma level of vasopressin but had no effect on plasma beta-endorphin/beta-lipotropin. The i.v. administration of 10 micrograms d(CH2)5Tyr(Me) AVP, a vasopressin antagonist, prevented the inhibition of gastric secretion induced by i.c.v. administration of 3 micrograms PGE2 to pylorus-ligated rats. The results indicate that the central antisecretory action of PGE2 is due to the release of vasopressin from the pituitary gland.
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PMID:Centrally administered PGE2 inhibits gastric secretion in the rat by releasing vasopressin. 609 7

Basal and stimulated secretion of immunoreactive ACTH, LPH and beta-endorphin from four human pituitary tumours has been studied in vitro using a superfused, isolated cell system. Chromatography of cell secretions under acid-dissociating conditions demonstrated that the human tumor cells released immunoreactive peptides with the elution profiles of alpha h (1-39) ACTH, beta h-LPH, gamma h-LPH and beta h-endorphin confirming that beta h-endorphin is secreted by human pituitary tumour cells and is not formed by enzymic cleavage from beta h-LPH in blood. No alpha- or beta h-MSH, nor any higher molecular weight forms of ACTH or LPH were detected. The cells from all four tumours responded to stimulation with rat stalk-median eminence extract (SME) and synthetic AVP with a concomitant release of ACTH, beta-LPH, gamma-LPH and beta-endorphin. In contrast to the isolated rat anterior pituitary cells, the pattern of responses to SME and AVP were indistinguishable and the release provoked by rat SME could be accounted for virtually entirely by its vasopressin content. No stimulation of release was observed when the cells were exposed to a variety of biogenic amines. Addition of hydrocortisone to the perfusion buffer of two tumours resulted in a slow inhibition of both basal and stimulated ACTH and LPH release. These data demonstrate that human pituitary tumour tissue from patients with Cushing's disease and Nelson's syndrome can be studied in vitro and that such studies may contribute to a greater understanding of the aetiology of these diseases.
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PMID:Secretion of ACTH, LPH and beta-endophin from human pituitary tumours in vitro. 625 99

Basal and stimulated secretion of N-terminal pro-opiocortin (Pro-gamma-MSH), ACTH and LPH from seven pituitary and three ectopic ACTH secreting tumours have been studied in vitro using a perfused isolated cell system. The peptides were shown to be released concomitantly and in equimolar amounts. The pituitary tumours responded to stimulation with rat stalk median eminence extracts (SME) and synthetic AVP. However, peptide release from the ectopic tumours, although pulsatile, remained autonomous. Prior to surgery, gel-chromatographic profiles of plasma immunoreactive ACTH showed only one peak, which eluted in the position of 1-39 ACTH, in patients with the pituitary tumours, but there was a second peak of large molecular weight ACTH present in the plasma from those with the ectopic ACTH syndrome. This second form of ACTH could not be detected in any of the tumour cell column effluents. An eighth pituitary tumour was atypical, in its unusually large size, clinically aggressive nature and spectrum of peptide release. Although peptide release in response to stimulation with SME was similar to that observed with the other pituitary tumours, the chromatography of the plasma ACTH resembled the ectopic plasma pattern, showing two peaks of immunoreactivity.
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PMID:Pro-opiocortin related peptides in human pituitary and ectopic ACTH secreting tumours. 630 38

The transport properties of several peptides across blood-brain barrier (BBB) have been investigated theoretically in terms of simple diffusion and facilitated diffusion processes. Comparison of the calculated results from the simple diffusion and the experimental data reveals the presence of the facilitated diffusion of these substances which we have conceived of as a carrier-mediated process. The values of the partition coefficients f for these peptides were in the range 7 X 10(-4) less than or equal to f less than or equal to 200 X 10(-4). The calculated f values gave permeabilities, Ps, in lipids between 10(-7) less than or equal to Ps less than or equal to 14 X 10(-7) cm/s. These values were then used to estimate the extraction for peptides from simple diffusion alone which vary from 0.3 to 3.5% compared with the experimental extraction (0.4-12%) indicating the inadequacy of the simple diffusion alone to explain the experimental data. As for the carrier-mediated facilitated diffusion process we have used the activated-complex theory. The extraction in this case depends on the maximal rate of transport (Tmax)f and the reciprocal of the affinity constant Kt for the transport of peptides through BBB. We have deduced that (Tmax)f approximately 0.46 X 10(-3) pmol/g X s and Kt approximately 0.35 nM for Met-enkephalin (Met-ENK), Leu-enkephalin (Leu-ENK), glutathione, carnosine, alpha-MSH and MIF and (Tmax)f approximately 10 X 10(-3) pmol/g X s and Kt approximately 7 nM for AVP, beta LT, beta E and alpha E to explain the observed results. We have also obtained the quantitative variation of extraction with concentration of peptides in the brain-capillary and have established that the extraction decreases with increasing concentration of peptides, tending to a small constant value at high concentrations. It has been inferred that carrier-mediated facilitated diffusion is important for the transport of peptides across BBB.
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PMID:Theoretical interpretation of extraction (in brain) of peptides including concentration variations. 643 51

High performance liquid chromatography (HPLC) was used for the separation of many neuropeptides. Chromatography was carried out using a Hitachi Model 638 high performance liquid chromatograph. Peptides and samples from tissue dissolved in an aqueous buffer were injected into a stainless-steel column (4 X 250mm) packed with Hitachi #3053 (octadecylsilane). The aqueous buffer consisted of NaH2PO4 and H3PO4. After a loading phase (0% organic solvent) of 1 min, the peptides were sequentially eluted at room temperature using a gradient of organic solvent (acetonitrile or methanol, 0-60%). The eluted polypeptides were detected by UV absorbance at 220nm, and then they were collected for subsequent bio and radioimmunoassay using a fraction collector. The gradient of methanol or acetonitrile in 0.02M NaH2PO4, 0.1% H2PO4 was useful for separating small molecular peptides. The gradient of acetonitrile in 0.05-0.1M NaH2PO4, 0.1% H2PO4 was useful for separating many neuropeptides including ACTH related peptides. Retention times of chromatographed polypeptides showed good reproducibility. Good reproducibility was also found in peak areas of these peptides. A linear relationship was observed between the doses of peptides and their peak areas. The extracts of rat pituitary neurointermediate lobe showed several peaks of UV absorbance on PHLC; some of them coincided with AVP, oxytocin, alph-MSH, CLIP and beta-endorphin but others were unidentified. AVP immunoreactivity showed one peak which coincided with the AVP peak of UV absorbance, but ACTH immunoreactivity showed 5-6 peaks. Thus, many polypeptides were well separated using HPLC by changing the eluting condition. The simplicity, speed, good reproducibility and good quality of the separations render this technique suitable for purification and quantitative analysis of neuropeptides, and the combination of HPLC, radioimmunoassay and bioassay gives very fine analysis of neuropeptides.
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PMID:[The separation of neuropeptides by high performance liquid chromatography and its application to the analysis of peptides in the rat pituitary neurointermediate lobe (author's transl)]. 680 25

Histamine administered intraperitoneally increased, in a dose-dependent manner, AVP, OXT and PRL levels in plasma of rats, whereas alpha-MSH levels were not affected. Levels of AVP in plasma after histamine 20.0 mg/kg treatment were approximately 100-fold higher than those of controls, while OXT and PRL levels were approximately 7-fold higher after this treatment. CSF content of AVP, OXT, PRL and alpha-MSH was not influenced by histamine, indicating that a stimulated release of hormones from the pituitary into the blood is not accompanied by a concomitant increase of secretion of these hormones into the CSF. Convulsions induced by pentylenetetrazol were accompanied by a temporary increase in AVP levels and by strongly and consistently elevated OXT levels in plasma. PRL and alpha-MSH plasma levels were affected in a biphasic manner. A convulsion type 1 induced elevated PRL levels and diminished alpha-MSH levels, while a convulsion type 2 had no effect on plasma PRL concentration, but increased the concentration of alpha-MSH. Only the level of OXT in CSF was increased after a pentylenetetrazol-induced convulsion type 1. The present data suggest that histamine affects the release of AVP, while pentylenetetrazol might act more specifically on the OXT-releasing system. Furthermore, a possible relationship between the pentylenetetrazol-induced increase of OXT levels in the CSF and amnesia is suggested.
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PMID:Hypophyseal hormone levels in blood and cerebrospinal fluid in response to histamine and pentylenetetrazol. 715 99


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