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Brouns F, Shewry PR. Do gluten peptides stimulate weight gain in humans? NUTR BULL 2022; 47:186-198. [PMID: 35915782 PMCID: PMC9328276 DOI: 10.1111/nbu.12558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/05/2022] [Accepted: 04/19/2022] [Indexed: 02/06/2023]
Abstract
Observations from animal and in vitro laboratory research, and anecdotal evidence, have led to the suggestion that gluten consumption stimulates weight gain by the presence of peptides expressing opioid activity. Another proposed mechanism is that gluten peptides decrease resting energy expenditure resulting in a positive energy balance. In order to induce such effects in vivo, intact food peptides must be absorbed in sufficient quantities, remain intact in the blood for sufficient time to have long‐lasting biological activity and bind to receptors involved in appetite, satiety and energy regulation. However, although peptides from food may pass from the intestine into the blood in extremely low quantities, they are generally rapidly degraded by plasma and vasculum‐bound aminopeptidases, resulting in very short half‐lives and loss of bioactivity. At present, gluten peptide sequences that influence regulators of energy metabolism have not been identified. Furthermore, data on the quantitative absorption of gluten peptides in the blood stream, their stability and lasting bioactivity are also lacking. Therefore, there is no evidence for proposed effects on driving appetite by the brain, nor on energy expenditure and weight gain. Furthermore, the level of overweight observed in various countries appears to be independent of the level of wheat consumption, and abundant observational evidence in humans shows that the levels of gluten consumption are neither related to daily calorie intake nor to BMI. This narrative review therefore discusses the proposed effects of gluten on bodyweight (BW) and putative biological mechanisms in the light of the current evidence.
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Affiliation(s)
- Fred Brouns
- School for Nutrition and Translational Research in Metabolism Maastricht University Maastricht The Netherlands
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Moss LM, Berends CL, van Brummelen EMJ, Kamerling IMC, Klaassen ES, Bergmann K, Ville V, Juarez-Perez V, Benichou AC, Groeneveld GJ. First-in-human trial to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of STR-324, a dual enkephalinase inhibitor for pain management. Br J Clin Pharmacol 2021; 88:103-114. [PMID: 34046921 PMCID: PMC9292820 DOI: 10.1111/bcp.14931] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 04/15/2021] [Accepted: 04/18/2021] [Indexed: 11/28/2022] Open
Abstract
AIM Dual enkephalinase inhibitors (DENKIs) are involved in the regulation of nociception via opioid receptors. The novel compound STR-324 belongs to the DENKI pharmacological class. This first-in-human study evaluated the safety, tolerability, pharmacokinetics and pharmacodynamics of STR-324 in healthy male participants. METHODS This was a randomised, double-blind, placebo-controlled ascending dosing study in two parts: in part 1, 30 participants received 0.004-11.475 mg h-1 of STR-324 or placebo (ratio 4:1) by 4 h intravenous infusion in a two-group, partial crossover design with four treatment periods separated by 1 month wash-out, and in part 2, 48 participants divided into three groups received either the active drug (1.25-11.25 mg h-1 ) or placebo (ratio 3:1) by 48 h intravenous infusion. Safety and tolerability parameters, pharmacokinetics and pharmacodynamic effects on neurocognitive and neurophysiological tasks and on a nociceptive test battery were evaluated. RESULTS No clinically relevant changes in safety parameters were observed. All treatment-emergent adverse events were mild and transient. The pharmacokinetics of STR-324 could not be determined due to most concentrations being below quantifiable limits. STR-324 metabolite concentrations were measurable, showing dose proportionality of Cmax and AUCinf with an estimated t1/2 of 0.2-0.5 h. Significant changes in pharmacodynamic parameters were observed, but these were not consistent or dose-dependent. CONCLUSION STR-324 displayed favourable safety and tolerability profiles at all doses up to 11.475 mg h-1 . Although pharmacokinetic characterisation of STR-324 was limited, dose proportionality could be assumed based on major metabolite data assayed as proxy. No clear effects on nociceptive thresholds or other pharmacodynamic measures were observed. TRIAL REGISTRY EudraCT (2014-002402-21) and toetsingonline.nl (63085).
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Affiliation(s)
- Laurence M Moss
- Centre for Human Drug Research, Leiden, the Netherlands.,Leiden University, Leiden, the Netherlands
| | - Cecile L Berends
- Centre for Human Drug Research, Leiden, the Netherlands.,Leiden University, Leiden, the Netherlands
| | | | - Ingrid M C Kamerling
- Centre for Human Drug Research, Leiden, the Netherlands.,Leiden University, Leiden, the Netherlands
| | | | | | | | | | | | - Geert Jan Groeneveld
- Centre for Human Drug Research, Leiden, the Netherlands.,Leiden University, Leiden, the Netherlands
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Salaga M, Mokrowiecka A, Jacenik D, Cygankiewicz AI, Malecka-Panas E, Kordek R, Krajewska WM, Sobocinska MK, Kamysz E, Fichna J. Systemic Administration of Sialorphin Attenuates Experimental Colitis in Mice via Interaction With Mu and Kappa Opioid Receptors. J Crohns Colitis 2017; 11:988-998. [PMID: 28333341 DOI: 10.1093/ecco-jcc/jjx043] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 03/17/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND AND AIMS Pharmacological treatment and/or maintenance of remission in inflammatory bowel disease [IBD] is currently one of the biggest challenges in the field of gastroenterology. Here we aimed to assess the anti-inflammatory effect and the mechanism of action of sialorphin, the natural blocker of the endogenous opioid peptide-degrading enzymes neprilysin [NEP] and aminopeptidase N [APN], in mouse models of IBD and the changes in the expression of these enzymes in IBD patients. METHODS We used two models of experimental colitis in mice [2,4,6-trinitrobenzene sulphonic acid [TNBS]- and dextran sulphate sodium [DSS]-induced]. Macroscopic score, ulcer score, colonic wall thickness, and myeloperoxidase [MPO] activity were recorded. Additionally, we measured the expression of NEP and APN in the colon of IBD patients and healthy controls. RESULTS We showed that sialorphin attenuated acute, semichronic, and relapsing TNBS-induced colitis in mice after systemic administration, and its anti-inflammatory action is associated with mu and kappa opioid receptors. CONCLUSIONS We show that indirect stimulation of opioid receptors by the blockade of NEP and APN is a promising pharmacological strategy for the treatment of IBD, and may become of greater importance than the use of classical opioid agonists.
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Affiliation(s)
- M Salaga
- Department Biochemistry, Medical University of Lodz, Lodz, Poland
| | - A Mokrowiecka
- Department of Digestive Tract Diseases, Medical University of Lodz, Lodz, Poland
| | - D Jacenik
- Department of Cytobiochemistry, University of Lodz, Lodz, Poland
| | - A I Cygankiewicz
- Department of Molecular Biotechnology, University of Gdansk, Gdansk, Poland
| | - E Malecka-Panas
- Department of Digestive Tract Diseases, Medical University of Lodz, Lodz, Poland
| | - R Kordek
- Department of Pathology, Faculty of Medicine,Lodz, Poland
| | - W M Krajewska
- Department of Cytobiochemistry, University of Lodz, Lodz, Poland
| | - M K Sobocinska
- Department of Molecular Biotechnology, University of Gdansk, Gdansk, Poland
| | - E Kamysz
- Department of Molecular Biotechnology, University of Gdansk, Gdansk, Poland
| | - J Fichna
- Department Biochemistry, Medical University of Lodz, Lodz, Poland
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Abstract
Eighteen male cluster headache (CH) inpatients within a CH series participated in this research. Blood samples were drawn from patients at least 6-hour pain-free after the last acute CH episode and then shortly prior (SP), during, and soon after (SA) a new acute CH attack. Three healthy male, age-comparable drug-free volunteers served as controls; 5 samples were obtained from each of these individual over a 24-hour period. Individual patient's methionine-enkephalin (MET) plasma concentration showed significant changes, and in some subjects, dramatic changes, during the different phases of a single CH episode. Peptide levels followed a general pattern of higher plasma concentration SP to an acute CH attack, followed by decreased levels during the attack itself, and falling even further SA the acute episode. Consistently, 16 of the 18 patients tested showed pre-CH peptide levels significantly higher (arbitrarily the authors considered values 20% or more as "significant") than their own values obtained during the acute CH pain phase, with observed differences reaching 80% or more in 7 of these individuals. For about half of these patients, peptide concentration during the acute CH episode was significantly above the control's range (68.2-87.6 pg MET/mL; control's circulating MET concentration remaining essentially unchanged during a 24-hour period). MET levels were further decreased in essentially all of the post-CH samples, with values falling within (n = 6) or even further below than those in the control's range (n = 11). Neither age, time of CH occurrence, nor patient's use of a number of medications known for failing to influence plasma MET degradation kinetics seemed to significantly influence MET levels. These results might help in the biochemical characterization of the actual phases of a CH episode. Developing drugs modulating MET bioavailability could lead to novel antinociceptive agents useful for the treatment of CH's associated pain.
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van den Brink OWV, Cochrane AD, Rosenfeldt FL, Penny DJ, Pepe S. Increased myocardial methionine-enkephalin with reduced arterial oxygenation in congenital heart disease. J Paediatr Child Health 2014; 50:E63-7. [PMID: 20626583 DOI: 10.1111/j.1440-1754.2010.01794.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Cardiac opioid peptides have been identified to exert important adaptive metabolic signalling for cardioprotection against ischaemia or hypoxia-related injury. AIMS To determine myocardial methionine-enkephalin content in children with hypoxemic congenital heart defects and to correlate myocardial content of methionine-enkephalin with the extent of arterial oxygen desaturation. METHODS Children (n= 20, median age of 16 months), undergoing cardiac surgical repair (tetralogy of Fallot, 17/20), were included in this study. Arterial oxygen saturation was measured on admission. Myocardial samples obtained during surgery were assayed via radioimmunochemistry for methionine-enkephalin content. RESULTS Greater methionine-enkephalin content was measured in the right ventricles of the patients suffering from recent cyanotic spells compared with those with no recent spells (cyanotic spells: 2418 ± 844 pg/g wet weight tissue, n= 6; no spells: 1175 ± 189 pg/g wet weight tissue, n= 14, P= 0.04). An inverse correlation was evident between the arterial oxygen saturation and myocardial methionine-enkephalin content. CONCLUSION Myocardial methionine-enkephalin levels increase with the severity of hypoxic stress in congenital cardiac disease and may play an important adaptive role in countering adrenergic over-activity and related excess demand on myocardial metabolic capacity.
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Affiliation(s)
- Olivier W V van den Brink
- Department of Cardiothoracic Surgery, Alfred Hospital, Department of Surgery, Monash University, Murdoch Children's Research Institute, Critical Care and Neurosciences, Heart Research, Victorian Paediatric Cardiac Surgery Unit, Department of Cardiology, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
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Mosnaim AD, Chuang F, Wolf ME. Degradation kinetics of methionine5-enkephalin by cerebrospinal fluid: in vitro studies. Am J Ther 2010; 18:9-13. [PMID: 20838201 DOI: 10.1097/mjt.0b013e3181f0593c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Changes in the levels or biochemistry of cerebrospinal fluid (CSF) neuropeptides with opioid-like properties have been suggested to reflect alterations in specific biological processes. We have determined various kinetic parameters for methionine-enkephalin (MET) degradation by CSF samples from nonneurological patients. Study subjects included 9 males (51-67 years of age) and 5 females (47-61 years of age). Aliquots, removed from an incubation vessel containing buffer, CSF, and peptide [tyr-3',5'-H(N)MET], were analyzed for tyrosine and other degradation products. Essentially all of the labeled tyrosine from the added MET was recovered as free amino acid after 60 minutes of incubation (1:2 ratio, vol:vol; optimum pH 7.4; and temperature 37°C); other possible peptide metabolites (>3%) were not detected. Irrespective of age or gender, the peptide's degradation half-life and initial velocity values were in a limited range; t1/2 26.2 ± 5.5 and 20.8-33.8 minutes, and Iv 0.03 ±0.01 and 0.02-0.03 pg of peptide per milligram protein per minute. Km and Vmax values were 0.19 ± 0.02 and 0.17-0.21 mM, and 9.8 ± 2.2 and 7.6-12.0 μmol·L·min, respectively. Neither CSF sample storage time (up to a year) nor repeated freezing and thawing (up to 3 times over a year) altered the kinetics or products of this reaction. These preliminary findings might serve as reference values when conducting similar studies using CSF from patients diagnosed with specific neurological conditions; significant alterations in MET degradation profile in such a population could provide valuable biological markers for diagnostic and treatment purposes.
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Affiliation(s)
- Aron D Mosnaim
- Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science/Chicago Medical School, N. Chicago, IL 60064, USA.
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Jia MR, Wei T, Xu WF. The Analgesic Activity of Bestatin as a Potent APN Inhibitor. Front Neurosci 2010; 4:50. [PMID: 20631848 PMCID: PMC2903224 DOI: 10.3389/fnins.2010.00050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 06/10/2010] [Indexed: 11/13/2022] Open
Abstract
Bestatin, a small molecular weight dipeptide, is a potent inhibitor of various aminopeptidases as well as LTA4 hydrolase. Various physiological functions of Bestatin have been identified, viz.: (1) an immunomodifier for enhancing the proliferation of normal human bone marrow granulocyte-macrophage progenitor cells to form CFU-GM colonies; Bestatin exerts a direct stimulating effect on lymphocytes via its fixation on the cell surface and an indirect effect on monocytes via aminopeptidase B inhibition of tuftsin catabolism; (2) an immunorestorator and curative or preventive agent for spontaneous tumor; Bestatin alone or its combination with chemicals can prolongate the disease-free interval and survival period in adult acute or chronic leukemia, therefore, it was primarily marketed in 1987 in Japan as an anticancer drug and servers as the only marketed inhibitor of Aminopeptidase N (APN/CD13) to cure leukemia to date; (3) a pan-hematopoietic stimulator and restorator; Bestatin promotes granulocytopoiesis and thrombocytopoiesis in vitro and restores them in myelo-hypoplastic men; (4) an inhibitor of several natural opioid peptides. Based on the knowledge that APN can cleave several bioactive neuropeptides such as Met-enkaphalins, Leu-enkaphalins, beta-Endorphin, and so on, the anti-aminopeptidase action of Bestatin also allows it to protect endopeptides against their catabolism, exhibiting analgesic activity. Although many scientific studies and great accomplishments have been achieved in this field, a large amount of problems are unsolved. This article reviews the promising results obtained for future development of the analgesic activity of Bestatin that can be of vital interest in a number of severe and chronic pain syndromes.
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Affiliation(s)
- Mei-Rong Jia
- School of Pharmacy, Shandong UniversityJinan, Shandong, China
| | - Tao Wei
- School of Public Health, Shandong UniversityJinan, Shandong, China
| | - Wen-Fang Xu
- School of Pharmacy, Shandong UniversityJinan, Shandong, China
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Bacitracin-Sensitive Aminopeptidase(s) Degradation of Methionine5-Enkephalin by Human Brain Putamen and Hippocampus Preparations: Inhibition by Phenothiazine Drugs. Am J Ther 2009; 16:512-6. [DOI: 10.1097/mjt.0b013e3181bbf6e9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Degradation Kinetics of Methionine5-Enkephalin by Select Brain Areas From Patients With Chronic Schizophrenia. Am J Ther 2008; 15:126-30. [DOI: 10.1097/mjt.0b013e31815db845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mosnaim AD, Nguyen TD, Tse R, Puente J, Couceyro P, Wolf ME. In vitro Methionine5-Enkephalin Degradation Kinetics by Human Brain Preparations. Neurochem Res 2007; 33:81-6. [PMID: 17676390 DOI: 10.1007/s11064-007-9418-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 06/18/2007] [Indexed: 12/01/2022]
Abstract
Incubation of [3H]-tyrosine methionine5-enkephalin (MET) with human brain preparations (100,000g supernatant; sections of the limbic system, thalamus, basal ganglia, cerebellum, and cortex) results in its rapid and complete degradation; over 95% of the initial labeled tyrosine is recovered as the free aminoacid within 10 min. Results show a considerable range in the peptide initial velocity (Iv) and half-life (t1/2) degradation values obtained from different brain sections of individual brains, either from the same or from different main brain areas. This relatively wide range of values was scattered, failing to identify consistent differences between the various brains areas studied. Differences in brain tissue storage time or repeated sample freezing and thawing failed to alter significantly either of these kinetic parameters of MET metabolism. Peptide degradation rate (optimum pH and temperature of 7.4 and 37 degrees C, respectively) was concentration-dependent inhibited by known aminopeptidase inhibitors (puromycin, bacitracin, and bestatin, and to a lesser extent by thioridazine). However, it was not significantly affected by either N-carboxymethyl phenyl leucine, captopril or thiorphan [dipeptidyl peptidase(s) or peptidyl dipeptidase(s) inhibitors, respectively]. A better understanding of the mechanisms regulating brain MET metabolism may contribute to the rational design of pharmacological strategies based in the modulation of its bioavailability.
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Affiliation(s)
- Aron David Mosnaim
- Department of Cellular and Molecular Pharmacology, RFUMS/Chicago Medical School, N. Chicago, IL 60064, USA.
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Mosnaim AD, Puente J, Ranade V, Hoang C, Wolf ME. Inhibition of human plasma leucine5-enkephalin aminopeptidase hydrolysis by various endogenous peptides and a select number of clinically used drugs. Am J Ther 2005; 11:459-65. [PMID: 15543085 DOI: 10.1097/01.mjt.0000134785.42464.17] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We identified a number of clinically used drugs and biologically active endogenous peptides able to significantly decrease the rate of human plasmatic aminopeptidase (AP) leucine-enkephalin (LEU) degradation. Bacitracin, bestatin, fluvoxamine, and each of 4 peptides tested significantly increased, in a dose-dependent manner (10-10 M), LEU degradation half-life (t1/2) in each of 5 plasma samples studied. Each sample was obtained by pooling equal volume of 6 randomly selected, individual plasmas (4 male and 2 female healthy, drug-free volunteers). Thirty subjects (20 females and 10 males) participated in this study. With the exception of fluvoxamine, this inhibitory effect was lacking in various other commonly used drugs with widely different chemical structures and pharmacological profiles, eg, antidepressants (SSRIs, imipramine-like tricyclics, MAOIs), acute antimigraine agents (triptan class drugs), the nonselective beta-adrenergic antagonist propranolol, and serotonin receptor agonists and antagonists. Agents (concentration 10 M used as illustration), listed in decreasing order of LEU-AP inhibitory activity: substance P > angiotensin III > methionine-enkephalin > angiotensin II > fluvoxamine > bestatin gave t1/2 values (+/- SD) of 39.3 +/- 1.1, 29.4 +/- 0.8, 28.3 +/- 0.8, 27.4 +/- 0.7, 24.5 +/- 1.5, and 23.6 +/- 0.9 minutes, respectively. Control, bacitracin, and fluphenazine (known LEU-AP inhibitors were used for comparison) values of 11.8 +/- 1.0, 31.3 +/- 0.7, and 19.6 +/- 1.0 minutes, respectively. As expected, these drugs significantly decreased the initial velocity of peptide degradation; Iv values (+/- SD) of: 0.17 +/- 0.1 (0.02 +/- 0.01), 0.23 +/- 0.2 (0.02 +/- 0.01), 0.25 +/- 0.2 (0.02 +/- 0.01), 0.26 +/- 0.2 (0.03 +/- 0.01), 0.31 +/- 0.1 (0.03 +/- 0.01), and 0.33 +/- 0.1 (0.03 +/- 0.01), respectively; control, bacitracin, and fluphenazine: 1.10 +/- 0.3 (0.12 +/- 0.03), 0.20 +/- 0.1 (0.02 +/- 0.01), and 0.82 +/- 0.2 (0.08 +/- 0.02) pg LEU/min (pg LEU/mg protein/min), respectively. Results emphasize the selective nature of chemical structures required to significantly inhibit AP activity and provided information that could help the rational design of agents with high specificity in a biologic milieu containing multiple peptidases. In this case, targeted modulation of the bioavailability of LEU and other endogenous AP-degraded hormonal and nonhormonal peptides could be useful in the treatment of the pathophysiology associated with various disease conditions. Whether their development could find useful pharmacological applications remains to be explored.
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Affiliation(s)
- Aron D Mosnaim
- Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science/The Chicago Medical School, N. Chicago, Illinois 60064, USA.
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Fanciulli G, Dettori A, Fenude E, Demontis MP, Alberico E, Delitala G, Anania V. Intravenous administration of the food-derived opioid peptide Gluten Exorphin B5 stimulates prolactin secretion in rats. Pharmacol Res 2003; 47:53-8. [PMID: 12526862 DOI: 10.1016/s1043-6618(02)00267-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gluten Exorphin B5 (GE-B5) is a food-derived opioid peptide, identified in vitro in enzymatic digests of wheat gluten. It has been suggested that this peptide may play a regulatory role on pituitary secretion, since it stimulates prolactin (PRL) secretion when administered in the cerebral ventricles in rats. It is not known, however, if GE-B5 can exert this stimulatory action after peripheral administration. In order to clarify this aspect, we gave the following treatments to four groups of male rats: intravenous (i.v.) vehicle, GE-B5 3 mg/kg body weight i.v., naloxone intraperitoneally (i.p.) followed by vehicle i.v., naloxone i.p. followed by GE-B5 i.v. Blood samples for PRL were taken at intervals for 60 min after vehicle or GE-B5 administration. At the dose of 3 mg/kg body weight, GE-B5 induced a significant increase in PRL levels; naloxone completely abolished any effect of GE-B5 on PRL secretion. The present study indicates that GE-B5 stimulates PRL secretion after peripheral administration and that its action is mediated via classical opioid receptors; moreover, it identifies the minimum peptide dose which must reach the blood in order to exert its action on PRL secretion.
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Affiliation(s)
- Giuseppe Fanciulli
- Dipartimento-Struttura Clinica Medica-Patologia Speciale Medica, Istituto di Patologia Medica, University of Sassari, Viale San Pietro 8, 07100 Sassari, Italy.
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