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)

Loperamide is a peripheral opiate agonist able to inhibit ACTH secretion. In this work, the interactions between loperamide and two ACTH secretagogues, lysine vasopressin (LVP) and corticotropin-releasing hormone (CRH), were investigated in patients with Addison's disease. After loperamide (16 mg orally) or placebo administration, 5 patients received LVP (0.06 IU/kg i.v. over 1 h) and 6 patients received oCRH (1 micrograms/kg i.v. as bolus). In all patients loperamide induced a significant fall in plasma ACTH levels. LVP increased ACTH levels after both loperamide (from 48 +/- 17.3 to a peak of 95 +/- 21 pmol/l) and placebo (from 231 +/- 59.5 to 365 +/- 86.6 pmol/l): the interaction between treatments and time was not significant. CRH caused a rise in plasma ACTH after both loperamide (from 30 +/- 16.6 to a peak of 108 +/- 31 pmol/l) and placebo (from 98.5 +/- 47 to 211 +/- 61.7 pmol/l): the interaction between treatments and time was significant, and the first phase of CRH-induced ACTH secretion was significantly lower after loperamide. These data demonstrate that loperamide differently modifies the stimulatory action of LVP and CRH on ACTH secretion: namely, LVP and loperamide act in an additive manner, while CRH and loperamide interact in a non additive way. Although these findings might be explained by the involvement of different intracellular ACTH-secreting mechanisms, an influence of loperamide on some suprapituitary factors modulating the ACTH response is suggested.
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PMID:Loperamide, an opiate analog, differently modifies the adrenocorticotropin responses to corticotropin-releasing hormone and lysine vasopressin in patients with Addison's disease. 285 5

Loperamide was tested on electrically-evoked contractions using a series of "in vitro" isolated preparations, in comparison with morphine, met-enkephalin, beta-endorphin, ethylketocyclazocine used as representative agonists of mu, delta, epsilon, kappa receptors respectively. The IC50 of loperamide on myenteric plexus longitudinal muscle of guinea pig ileum was found to be 1.90 X 10(-7)M and equal to that of morphine. The IC50 on mouse vas deferens was found to be 13.02 X 10(-7)M. In this tissue, loperamide resulted as active as morphine, but 54 times less active than met-enkephalin (IC50 0.24 X 10(-7)M). On the rat vas deferens where, as expected, beta-endorphin was strongly active (IC50 1.38 X 10(-7)M), morphine exerted a stimulatory action within the range 10(-5)M-10(-4)M and loperamide was only poorly depressive. The Ke value of naloxone, a specific mu receptor antagonist, against loperamide in the guinea pig ileum was 3.83 nM, and in the mouse vas deferens was 82.87 nM indicating that loperamide in the guinea pig ileum acts on mu receptors while in the mouse vas deferens on another opiate receptor.
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PMID:Loperamide: evidence of interaction with mu and delta opioid receptors. 631 84

The effect of the antidiarrheal drug loperamide, a mu-opiate agonist, on ACTH secretion and biosynthesis, cAMP generation and phosphoinositide turnover was studied in rat anterior pituitary cell cultures. The cAMP-dependent protein kinase A pathway was stimulated with both corticotropin-releasing hormone (CRH; 2-5 nM) and the membrane-permeable Bu(2)cAMP (0.5-2.5 mM). The protein kinase C pathway was stimulated with 1 microM arginine vasopressin (AVP) and 1-10 nM phorbol 12-myristate 13-acetate (PMA). After 3.5 h, loperamide (10 microM) had no effect on basal ACTH levels but significantly suppressed CRH-induced ACTH release, in a dose-dependent manner, to 60 +/- 4% of control (100%) (p < 0.0001). After 24 h, basal proopiomelanocortin mRNA was significantly decreased to 50% of control by loperamide (p < 0.05). The suppressive effect of loperamide on CRH-induced ACTH secretion was not reversible by naloxone (0.1-1,000 microM). Morphine (0.01-10 microM) had no effect on basal and CRH-induced ACTH secretion. Loperamide did not influence basal and CRH-induced adenylate cyclase activity in anterior pituitary cell membrane preparations, but it significantly blunted Bu(2)cAMP-induced ACTH secretion in cell culture from 100 +/- 4 to 77 +/- 4% (p < 0.05). In Ca(2+)-depleted medium (Ca2+ < 0.1 mM), loperamide had no suppressive effect on CRH-induced ACTH secretion. AVP-induced ACTH secretion was significantly suppressed by loperamide from 100 +/- 5 to 74 +/- 3% (p < 0.0001), while basal and AVP-induced inositol 1-phosphate generation and PMA-induced ACTH secretion were not affected by loperamide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Loperamide inhibits corticotrophic cell function by a naloxone-insensitive mechanism in the rat in vitro. 823 60