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 intermediate lobe of the pituitary gland synthesizes the multifactorial precursor molecule pro-opiomelanocortin (POMC), from which, through a process of post-translational enzymatic processing, beta-endorphin-(1-31) (beta E) and a variety of N alpha-acetylated and C-terminally shortened forms of this peptide are generated. Using an in vitro superfusion system, the release of these endorphins from intact rat neurointermediate lobes (NILs) was investigated under basal and isoproterenol (ISO) stimulated conditions. Superfusion of NILs with the beta-adrenergic agonist ISO (30 min pulse) resulted in a rapid, sustained and concentration-dependent stimulation of the release of beta E-like immunoreactivity (beta E-IR) over basal as determined with an antiserum directed against the C-terminus of the beta E- (1-31) sequence (10(-6) M: + 145%; 10(-7) M: + 73%; 10(-8) m: + 41%). The release of N(alpha)-acetylated-endorphin-like immunoreactivity (AcE-IR) was stimulated to a similar extent. These effects of ISO were antagonized by the competitive alpha-adrenoceptor antagonist propranolol in a concentration-dependent manner, indicating the involvement of alpha-adrenoceptors. The beta-related peptides released from the NILs under basal and ISO-stimulated conditions were further characterized, based on their retention times in a reversed-phase HPLC system and their reactivity with specific antisera recognizing respectively the midportion of beta E, the N-terminus of acetylated endorphins, the C-terminus of tau-endorphin (beta E-(1-17); tau E), or the C-terminus of alpha-endorphin (beta E-(1-16); alpha E). In HPLC fractionated superfusates 10 peaks were resolved that reacted with the midportion beta E antiserum. In superfusates collected under basal conditions, three major peaks possessed chromatographical and immunological characteristics of Ac beta E-(1-26), Ac beta E- (1-27) Ac beta E-(1-31). In addition, a prominent peak was found eluting around the retention time of beta E-(1-31), that contained both acetylated and non-acetylated material. Six smaller peaks were observed, with the characteristics of beta E-(1-26) and beta E-(1-27) (these peptides were not resolved with the HPLC system used), Ac tau E, tau E, Aa alpha E, and des-tyrosine-alpha E (DT alpha E), respectively. In superfusates collected during superfusion of NILs with ISO (10(-6) M) all peaks were increased. However, those eluting as beta E-(1-31), beta E-(1-26)/beta E-(1-27), Ac beta E-(1-26) and Ac tau E appeared to be preferentially stimulated.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Isoproterenol-stimulated release of beta-endorphin and related peptides from the rat pituitary neurointermediate lobe in vitro: evidence for preferential release of certain molecular forms of beta-endorphin. 228 Aug 22

1. Macroscopic and single-channel currents were recorded from voltage-clamped neurones in the abdominal and pleural ganglia of Aplysia californica in order to investigate conductance changes elicited by application of the endogenous peptide FMRFamide (Phe-Met-Arg-Phe-NH2) and related neuropeptides to the cell surface. 2. The Ca-dependent K current, IK(Ca), when elicited at a constant voltage by intracellular injection of Ca2+, was insensitive to FMRFamide or its derivative YGG-FMRFamide (Tyr-Gly-Gly-Phe-Met-Arg-Phe-NH2). 3. Under steady voltage clamp, certain cells responded to a brief puff of FMRFamide or YGG-FMRFamide with a transient outward current lasting about 1 min. Unclamped cells responded with a corresponding hyperpolarization. These responses reversed at about -75 mV. Ion substitution indicated that the current is carried by K+. 4. FMRFamide and YGG-FMRFamide were equally effective in activating the outward current, whereas FMRF, met-enkephalin and leu-enkephalin were ineffective. 5. At voltages negative to -30 mV and, in the absence of extracellular Ca2+, also at more positive potentials, the FMRFamide-sensitive current showed no voltage dependence beyond that predicted from constant-field considerations. 6. The response to FMRFamide was relatively insensitive to extracellular tetraethylammonium (TEA, KD approximately 75 mM) and 4-aminopyridine (4-AP, KD approximately 6 mM). It was suppressed in Ba-containing solutions, but was unaffected by injection of the Ca chelating agent EGTA. The response was blocked by serotonin and other agents known to elevate intracellular adenosine 3',5'-phosphate (cyclic AMP) levels, and by direct injection of cyclic AMP into the cell. 7. In its pharmacological properties and lack of voltage dependence, the FMRFamide-activated current resembles the 'S' current, IK(S), a K current suppressed by application of serotonin in Aplysia neurones. 8. The similarity between the FMRFamide-sensitive current and the 'S' current was confirmed in cell-attached patch-clamp studies, in which activity of 'S' channels was found to be reduced by serotonin, and enhanced by FMRFamide. 9. Thus, FMRFamide may function in Aplysia to counteract the serotonergic modulation of 'S' channels, which has been proposed as a mechanism of presynaptic plasticity in this mollusc.
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PMID:Modulation of potassium conductances by an endogenous neuropeptide in neurones of Aplysia californica. 244 63

A hypothesis was examined that carboxypeptidase H (CpAse H), which is known to catalyse the release of lysine and arginine from the C-terminus of peptides, can also release histidine, tyrosine, and phenylalanine. Synthetic peptides terminating in -His-Lys or -Tyr-Lys were used as model substrates for the enzyme and amino acid analysis was employed to detect release of the terminal amino acids. With N-acetyl-beta-Ala-Asn-Ala-His-Lys and N-acetyl-beta-Ala-Asn-Ala-Tyr-Lys, which correspond to intermediates in the processing of porcine and human beta-endorphin, lysine was removed rapidly and quantitatively but no release of histidine or tyrosine could be detected. To allow more sensitive analysis, radiolabelled substrates were employed and the amounts of the products formed on incubation with CpAse H were determined after separation by ion-exchange chromatography. With 125I-D-Tyr-Ala-His-Lys-Lys as substrate at pH 5.7, very small amounts of D-Tyr-Ala were released; the main product was D-Tyr-Ala-His. At pH 5.0 the release of histidine from 125I-D-Tyr-Ala-His took place 6,000 times more slowly than the release of lysine from 125I-D-Tyr-Ala-Lys. When the tripeptides were incubated at pH 5 with porcine pituitary secretory granules, the lysine was released rapidly but no release of histidine could be detected. The results demonstrate that CpAse H catalyses the release of C-terminal histidine with great difficulty.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Catalysis of slow C-terminal processing reactions by carboxypeptidase H. 252 98

It is well established that in the pituitary gland corticotropin-releasing hormone (CRH) stimulates the release of beta-endorphin (beta-E) via a cAMP-linked mechanism. Studies of the mechanisms underlying the CRH stimulation of beta-E release from rat hypothalamic slices perifused in vitro are reported in this paper. The data indicate that both a cAMP-dependent and non-cAMP-dependent mechanism mediate the action of CRH in the hypothalamus. The presence of a cAMP-linked mechanism was suggested by the finding that cholera toxin (0.1-10 nM) and forskolin (2.5 x 10(-6) M), both of which act to raise intracellular cAMP levels, stimulated the release of beta-E. In both cases, no further stimulation was seen upon addition of CRH (10(-8)M). However, it was also found that preincubation of the tissue with pertussis toxin (PTX; 100 ng/ml) prevented both the CRH- and forskolin-stimulated release of beta-E. This indicated that, in addition to the cAMP-linked mechanism, a further messenger system which is connected to a PTX-sensitive G-protein may also play a role. The latter observation also implied that a further substance, which utilizes a separate second messenger system, might be involved in the CRH stimulation of beta-E release. In this regard the role of arginine vasopressin (AVP) was investigated due to the known interaction between CRH and AVP in the pituitary gland. AVP (10(-12) to 10(-6)M) itself potently and dose-dependently stimulated beta-E release, producing a maximal increase of 220% above basal levels. The AVP-induced release of beta-E was abolished in PTX-pretreated hypothalami. The apparently obligatory requirement of AVP for the CRH-stimulation of beta-E release was illustrated by the finding that blockade of AVP receptors using the AVP antagonist d(CH2)5 [Tyr(OEt)2,Val4]-AVP almost completely attenuated the CRH-stimulated release of beta-E. Furthermore, in the presence of a high concentration of AVP (10(-6)M) no further stimulation of release was seen with CRH (10(-8)M). These data therefore strongly indicate that CRH acts via the intermediacy of AVP to release beta-E from hypothalamic slices in vitro and that two separate second messenger systems are involved: a cAMP-linked mechanism connected to a cholera toxin-sensitive G-protein (CRH) and a second system linked to a PTX-sensitive G-protein (AVP).
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PMID:A two-step mechanism by which corticotropin-releasing hormone releases hypothalamic beta-endorphin: the role of vasopressin and G-proteins. 252 50

It is well-known that prenatal chronic intermittent stress affects the reproductive system of both sexes. Investigating the effects of an acute maternal stress on the fetal neuroendocrine system, parameters such as hypothalamic catecholamines. CRF, GRF, LH-RH, beta-endorphin, hypophysial beta-endorphin and beta-LPH as well as plasma LH, corticosterone and androstenedione were measured. Pregnant rats of Wistar strain were exposed to restraint stress at day 22 of gestation or to forced immobilization at day 20 of gestation, respectively, and were sacrificed before stress and 10, 30, 60, and 120 min after starting stress. A decrease of fetal hypothalamic catecholamines and an increase of LH-RH content of the hypothalamus as well as of plasma catecholamines were observed under stress on day 22 of gestation. On day 20 of gestation hypothalamic beta-endorphin was depleted in male and unchanged in female fetuses under stress. A depletion of hypothalamic CRF was observed in male fetuses, whereas female fetuses showed an increase of hypothalamic CRF. An increase of GRF was found in fetuses of both sexes. Pituitary opioid content increased in fetuses of both sexes initially, but was depleted secondarily in male fetuses. The LH plasma level was markedly reduced in male, the corticosterone level was elevated in fetuses of both sexes as well as the androstenedione level in female fetuses. A simultaneous treatment of mother animals with tyrosine--a catecholamine precursor--prevented the depletion of hypothalamic and pituitary beta-endorphin as well as in part the reduction of plasma LH levels in male fetuses. Hypothalamic GRF content does not increase under tyrosine treatment in male fetuses, whereas in female fetuses the stress-induced increase of GRF content was rather pronounced under tyrosine than attenuated. These results indicate that fetal hypothalamic neurotransmitters and neurohormones (such as LH-RH, CRF, GRF and opioids) are involved in changing circulating hypophysial and adrenal hormones in fetuses exposed to maternal stress in late pregnancy, whereby sex-specific different pathways might be effective in fetal stress processing. The prenatal administration of tyrosine prevented at least in part--those neurohormonal changes which are affecting the sex-specific brain differentiation.
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PMID:Sex-specific effects on the fetal neuroendocrine system during acute stress in late pregnancy of rat and the influence of a simultaneous treatment by tyrosine. 253 47

Hypotension stimulates the secretion of adrenocorticotropin (ACTH) and vasopressin (AVP) and increases plasma levels of angiotensin II (ANG II). Because AVP and ANG II increase ACTH secretion, the present experiments were performed to evaluate the role of these peptides in the increases in plasma ACTH and glucocorticoid concentrations produced by hypotension in conscious dogs. This was accomplished by determining whether administration of receptor antagonists to vasopressin, [1-(beta-mercapto-beta,beta-cyclopentamethylene propionic acid), 2-(O-methyl)tyrosine]Arg8-vasopressin, and ANG II (saralasin), reduced the ACTH and glucocorticoid responses to infusion of four doses of the vasodilator nitroprusside. Nitroprusside (NP) infusion produced dose-dependent decreases in mean arterial pressure. Larger decreases in arterial pressure were produced in dogs pretreated with the AVP antagonist or with both saralasin and the vasopressin antagonist. Left and right atrial pressures also fell with NP infusion, and larger decreases in atrial pressures were found in dogs pretreated with the AVP antagonist. Finally, NP infusion increased plasma glucocorticoid concentration and plasma ACTH concentration. Both the glucocorticoid and the ACTH responses to hypotension were reduced in dogs given the AVP antagonist and in dogs given both saralasin and the AVP antagonist, but there was no difference in the effect of AVP blockade alone vs. the effect of combined AVP and ANG II blockade. These data suggest that AVP, but not ANG II, is required for normal glucocorticoid and ACTH responses to hypotension. They also suggest that AVP is necessary for normal maintenance of arterial blood pressure and atrial pressures during NP infusion.
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PMID:Vasopressin and ANG II in the control of ACTH secretion and arterial and atrial pressures. 253 37

alpha-Melanotropin (alpha-melanocyte-stimulating hormone, alpha-MSH) is a tridecapeptide, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2. The minimal sequence of alpha-MSH required for agonism in the lizard (Anolis carolinensis) skin bioassay was determined to be Ac-His-Phe-Arg-Trp-NH2 (Ac-alpha-MSH6-9-NH2). Smaller fragments of this sequence (Ac-alpha-MSH6-8-NH2, Ac-alpha-MSH6-7-NH2, Ac-alpha-MSH7-9-NH2, and Ac-alpha-MSH7-8-NH2) were devoid of melanotropic activity. The tetrapeptide, Ac-alpha-MSH7-10-NH2, was also inactive, thus again demonstrating the importance of His at position 6 for minimal activity. The important potentiating amino acids were found to be Met-4, Lys-11, and Pro-12, since Ac-alpha-MSH4-10-NH2 was about 100 times more potent than Ac-alpha-MSH5-10-NH2, and Ac-[Nle4]-alpha-MSH4-11-NH2 was about 40 times more potent than Ac-alpha-MSH4-10-NH2 or Ac-[Nle4]-alpha-MSH4-10-NH2. Ac-alpha-MSH4-12-NH2 and Ac-[Nle4]-alpha-MSH4-12-NH2 were equipotent and about six times more potent than alpha-MSH. Since [Nle4]-alpha-MSH and Ac-[Nle4]-alpha-MSH4-13-NH2 were both equipotent but about sixfold less active than Ac-[Nle4]-alpha-MSH4-12-NH2, it is clear that valine at position 13 does not contribute to the potency of alpha-MSH, except possibly in a negative way. The minimal message sequence for equipotency to alpha-MSH appears to be Ac-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-NH2, since the analog, Ac-[Nle4]-alpha-MSH4-11-NH2, was as active as the native hormone. Ser-1, Tyr-2, Ser-3, Glu-5, and Val-13 are not important for melanotropic potency since Ac-alpha-MSH4-12-NH2 was more potent than alpha-MSH, and Ac-alpha-MSH5-10-NH2 and Ac-alpha-MSH6-10-NH2 were equipotent, being about 4,000 times less active than alpha-MSH.
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PMID:Alpha-melanotropin: the minimal active sequence in the lizard skin bioassay. 253 78

The effect of the delta-selective agonist [D-Pen2,D-Pen5]enkephalin (DPDPE) on the antinociception produced by intracerebroventricular (i.c.v.) administration of the mu agonists morphine, [D-Ala2,NMePhe4,Gly-ol5]enkephalin (DAGO), [NMePhe3,D-Pro4]morphiceptin (PLO17), beta-endorphin, phenazocine, etorphine and sufentanil was studied in mice. Only the antinociceptive effects of morphine and normorphine were modulated by i.c.v. coadministration of a dose of DPDPE which did not produce any significant antinociception alone. Both the morphine and normorphine dose-response lines were displaced to the left in the presence of DPDPE. The delta-selective antagonist ICI174,864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH) (where Aib is alpha-aminoisobutyric acid) blocked the modulation of morphine antinociception by DPDPE. ICI 174,864 alone failed to produce either a significant increase or decrease of morphine, phenazocine, etorphine or beta-endorphin antinociception. The results of the present study provide support for the hypothesis that the enkephalins may function to modulate antinociception produced at the mu receptor; such modulation may come about via the existence of an opioid mu-delta receptor complex. The mu receptors existing in such a complex may be selectively activated by morphine and normorphine, but not the other mu agonists studied here. Thus, the enkephalins may function both to directly initiate, as well as to modulate, some forms of supraspinal mu receptor-mediated antinociception.
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PMID:Modulation of mu-mediated antinociception by delta agonists in the mouse: selective potentiation of morphine and normorphine by [D-Pen2,D-Pen5]enkephalin. 254 77

Pro-opiomelanocortin (POMC) synthesized in the anterior (AL) and intermediate lobe (IL) of the rat pituitary gland, is a prohormone precursor of several peptide hormones that may participate in the regulation of blood pressure. We therefore studied the biosynthesis of POMC by measuring the incorporation of 3H-tyrosine into the IL of 32-week-old spontaneously hypertensive rat (SHR) of the Aoki-Okamoto strain and their normotensive controls, the Wistar-Kyoto rat (WKY). Under basal conditions, POMC biosynthesis was significantly reduced in the SHR (1130 +/- 102 cpm/30 min/IL, n = 13) when compared to the WKY (1515 +/- 163 cpm/30 min/IL, N = 12, P less than 0.05, t test). There was also an inverse correlation between systolic blood pressure and POMC biosynthesis in both the WKY (Y = 8.4 +/- 1.38X + 2097 +/- 673, r = 0.86 +/- 0.06, N = 5), and SHR (Y = 5.7 +/- 1.8X + 1122 +/- 336 r = 0.57 +/- 0.13, N = 3). The decreased POMC biosynthesis was associated with a higher dopamine content in IL in SHR compared to WKY (1.56 +/- 0.53, n = 17 v 0.51 +/- 0.16, n = 17 pmol/IL, P less than 0.05, Mann-Whitney test). Oral administration of three different antihypertensive agents (propranolol, captopril, or hydralazine) for 12 weeks normalized blood pressure and POMC biosynthesis in the SHR but had no effect on either variable in the WKY. Because POMC biosynthesis in IL increased with normalization of blood pressure in the SHR, the decreased POMC biosynthesis in SHR may be a consequence rather than a cause of the elevated blood pressure in SHR.
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PMID:POMC biosynthesis in the intermediate lobe of the spontaneously hypertensive rat. 255 32

The structure of alpha-melanocyte-stimulating hormone (alpha-MSH) has been determined in the pars intermedia of the frog Rana ridibunda. Pulse-chase labeling of frog neurointermediate lobes with selective amino acids revealed that the composition of frog alpha-MSH is similar to that of alpha-MSH from all mammalian species yet studied. Tryptic mapping of nexly synthetized alpha-MSH generated two fragments with the following amino acid composition: (T1) Trp, Pro, Lys, Gly, Val and (T2) Tyr, Arg, Phe, His, Ser, Glu. Concurrently, alpha-MSH was purified from 100 neurointermediate lobes to apparent homogeneity by reverse-phase HPLC. The sequence of the peptide determined by automated Edman degradation was Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val. The structure of frog alpha-MSH is thus identical to mammalian des-N alpha-acetyl alpha-MSH and differs from the sequence of toad (Xenopus laevis) alpha-MSH only by the first residue (Ser instead of Ala). These results confirm that the sequence of alpha-MSH has been highly preserved during evolution.
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PMID:Melanin concentrating hormone. V. Isolation and characterization of alpha-melanocyte-stimulating hormone from frog pituitary glands. 255 47


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