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De Iuliis A, Montinaro E, Fatati G, Plebani M, Colosimo C. Diabetes mellitus and Parkinson's disease: dangerous liaisons between insulin and dopamine. Neural Regen Res 2022; 17:523-533. [PMID: 34380882 PMCID: PMC8504381 DOI: 10.4103/1673-5374.320965] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/08/2021] [Accepted: 03/04/2021] [Indexed: 11/13/2022] Open
Abstract
The relationship between diabetes mellitus and Parkinson's disease has been described in several epidemiological studies over the 1960s to date. Molecular studies have shown the possible functional link between insulin and dopamine, as there is strong evidence demonstrating the action of dopamine in pancreatic islets, as well as the insulin effects on feeding and cognition through central nervous system mechanism, largely independent of glucose utilization. Therapies used for the treatment of type 2 diabetes mellitus appear to be promising candidates for symptomatic and/or disease-modifying action in neurodegenerative diseases including Parkinson's disease, while an old dopamine agonist, bromocriptine, has been repositioned for the type 2 diabetes mellitus treatment. This review will aim at reappraising the different studies that have highlighted the dangerous liaisons between diabetes mellitus and Parkinson's disease.
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Affiliation(s)
| | - Ennio Montinaro
- Department of Neurology, Santa Maria University Hospital, Terni, Italy
| | | | - Mario Plebani
- Department of Medicine-DiMED, University of Padova, Italy
- Department of Medicine-DiMED, University of Padova, Padova, Italy; Department of Laboratory Medicine-Hospital of Padova, Padova, Italy
| | - Carlo Colosimo
- Department of Neurology, Santa Maria University Hospital, Terni, Italy
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Li M, Maddison LA, Page-McCaw P, Chen W. Overnutrition induces β-cell differentiation through prolonged activation of β-cells in zebrafish larvae. Am J Physiol Endocrinol Metab 2014; 306:E799-807. [PMID: 24473439 PMCID: PMC3962607 DOI: 10.1152/ajpendo.00686.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Insulin from islet β-cells maintains glucose homeostasis by stimulating peripheral tissues to remove glucose from circulation. Persistent elevation of insulin demand increases β-cell number through self-replication or differentiation (neogenesis) as part of a compensatory response. However, it is not well understood how a persistent increase in insulin demand is detected. We have previously demonstrated that a persistent increase in insulin demand by overnutrition induces compensatory β-cell differentiation in zebrafish. Here, we use a series of pharmacological and genetic analyses to show that prolonged stimulation of existing β-cells is necessary and sufficient for this compensatory response. In the absence of feeding, tonic, but not intermittent, pharmacological activation of β-cell secretion was sufficient to induce β-cell differentiation. Conversely, drugs that block β-cell secretion, including an ATP-sensitive potassium (K ATP) channel agonist and an L-type Ca(2+) channel blocker, suppressed overnutrition-induced β-cell differentiation. Genetic experiments specifically targeting β-cells confirm existing β-cells as the overnutrition sensor. First, inducible expression of a constitutively active K ATP channel in β-cells suppressed the overnutrition effect. Second, inducible expression of a dominant-negative K ATP mutant induced β-cell differentiation independent of nutrients. Third, sensitizing β-cell metabolism by transgenic expression of a hyperactive glucokinase potentiated differentiation. Finally, ablation of the existing β-cells abolished the differentiation response. Taken together, these data establish that overnutrition induces β-cell differentiation in larval zebrafish through prolonged activation of β-cells. These findings demonstrate an essential role for existing β-cells in sensing overnutrition and compensating for their own insufficiency by recruiting additional β-cells.
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Affiliation(s)
- Mingyu Li
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
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3
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Ustione A, Piston DW, Harris PE. Minireview: Dopaminergic regulation of insulin secretion from the pancreatic islet. Mol Endocrinol 2013; 27:1198-207. [PMID: 23744894 DOI: 10.1210/me.2013-1083] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Exogenous dopamine inhibits insulin secretion from pancreatic β-cells, but the lack of dopaminergic neurons in pancreatic islets has led to controversy regarding the importance of this effect. Recent data, however, suggest a plausible physiologic role for dopamine in the regulation of insulin secretion. We review the literature underlying our current understanding of dopaminergic signaling that can down-regulate glucose-stimulated insulin secretion from pancreatic islets. In this negative feedback loop, dopamine is synthesized in the β-cells from circulating L-dopa, serves as an autocrine signal that is cosecreted with insulin, and causes a tonic inhibition on glucose-stimulated insulin secretion. On the whole animal scale, L-dopa is produced by cells in the gastrointestinal tract, and its concentration in the blood plasma increases following a mixed meal. By reviewing the outcome of certain types of bariatric surgery that result in rapid amelioration of glucose tolerance, we hypothesize that dopamine serves as an "antiincretin" signal that counterbalances the stimulatory effect of glucagon-like peptide 1.
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Affiliation(s)
- Alessandro Ustione
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 702 Light Hall, Nashville, Tennessee 37232-0615, USA
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Ustione A, Piston DW. Dopamine synthesis and D3 receptor activation in pancreatic β-cells regulates insulin secretion and intracellular [Ca(2+)] oscillations. Mol Endocrinol 2012; 26:1928-40. [PMID: 22918877 DOI: 10.1210/me.2012-1226] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pancreatic islets are critical for glucose homeostasis via the regulated secretion of insulin and other hormones. We propose a novel mechanism that regulates insulin secretion from β-cells within mouse pancreatic islets: a dopaminergic negative feedback acting on insulin secretion. We show that islets are a site of dopamine synthesis and accumulation outside the central nervous system. We show that both dopamine and its precursor l-dopa inhibit glucose-stimulated insulin secretion, and this inhibition correlates with a reduction in frequency of the intracellular [Ca(2+)] oscillations. We further show that the effects of dopamine are abolished by a specific antagonist of the dopamine receptor D3. Because the dopamine transporter and dopamine receptors are expressed in the islets, we propose that cosecretion of dopamine with insulin activates receptors on the β-cell surface. D3 receptor activation results in changes in intracellular [Ca(2+)] dynamics, which, in turn, lead to lowered insulin secretion. Because blocking dopaminergic negative feedback increases insulin secretion, expanding the knowledge of this pathway in β-cells might offer a potential new target for the treatment of type 2 diabetes.
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Affiliation(s)
- Alessandro Ustione
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232-0615, USA
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Freeby M, Goland R, Ichise M, Maffei A, Leibel R, Harris P. VMAT2 quantitation by PET as a biomarker for beta-cell mass in health and disease. Diabetes Obes Metab 2008; 10 Suppl 4:98-108. [PMID: 18834437 DOI: 10.1111/j.1463-1326.2008.00943.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The common pathology underlying both type 1 and type 2 diabetes (T1DM and T2DM) is insufficient beta-cell mass (BCM) to meet metabolic demands. An important impediment to the more rapid evaluation of interventions for both T1DM and T2DM lack of biomarkers of pancreatic BCM. A reliable means of monitoring the mass and/or function of beta-cells would enable evaluation of the progression of diabetes as well as the monitoring of pharmacologic and other interventions. Recently, we identified a biomarker of BCM that is quantifiable by positron emission tomography (PET). PET is an imaging technique which allows for non-invasive measurements of radioligand uptake and clearance, is sensitive in the pico- to nanomolar range and of which the results can be deconvoluted into measurements of receptor concentration. For BCM estimates, we have identified VMAT2 (vesicular monoamine transporter type 2) as a biomarker and [(11)C] DTBZ (dihydrotetrabenazine) as the transporter's ligand. VMAT2 is highly expressed in beta-cells of the human pancreas relative to other cells of the endocrine and exocrine pancreas. Thus measurements of [(11)C] DTBZ in the pancreas provide an indirect measurement of BCM. Here we summarize our ongoing efforts to validate the clinical utility of this non-invasive approach to real-time BCM measurements.
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Affiliation(s)
- M Freeby
- Department of Medicine of Columbia University Medical Center, New York, NY, USA
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6
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Raffo A, Hancock K, Polito T, Andan G, Witkowski P, Hardy M, Barba P, Ferrara C, Maffei A, Freeby M, Goland R, Leibel RL, Sweet I, Harris PE. Role of vesicular monoamine transporter type 2 in rodent insulin secretion and glucose metabolism revealed by its specific antagonist tetrabenazine. J Endocrinol 2008; 198:41-9. [PMID: 18577569 PMCID: PMC2712213 DOI: 10.1677/joe-07-0632] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Despite different embryological origins, islet beta-cells and neurons share the expression of many genes and display multiple functional similarities. One shared gene product, vesicular monoamine transporter type 2 (VMAT2, also known as SLC18A2), is highly expressed in human beta-cells relative to other cells in the endocrine and exocrine pancreas. Recent reports suggest that the monoamine dopamine is an important paracrine and/or autocrine regulator of insulin release by beta-cells. Given the important role of VMAT2 in the economy of monoamines such as dopamine, we investigated the possible role of VMAT2 in insulin secretion and glucose metabolism. Using a VMAT2-specific antagonist, tetrabenazine (TBZ), we studied glucose homeostasis, insulin secretion both in vivo and ex vivo in cultures of purified rodent islets. During intraperitoneal glucose tolerance tests, control rats showed increased serum insulin concentrations and smaller glucose excursions relative to controls after a single intravenous dose of TBZ. One hour following TBZ administration we observed a significant depletion of total pancreas dopamine. Correspondingly, exogenous L-3,4-dihydroxyphenylalanine reversed the effects of TBZ on glucose clearance in vivo. In in vitro studies of rat islets, a significantly enhanced glucose-dependent insulin secretion was observed in the presence of dihydrotetrabenazine, the active metabolite of TBZ. Together, these data suggest that VMAT2 regulates in vivo glucose homeostasis and insulin production, most likely via its role in vesicular transport and storage of monoamines in beta-cells.
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Affiliation(s)
- Anthony Raffo
- Department of Medicine of Columbia University Medical Center, New York, NY, 10032, USA
| | - Kolbe Hancock
- Barnard College, Columbia University, New York, NY 10027, USA
| | - Teresa Polito
- Department of Medicine of Columbia University Medical Center, New York, NY, 10032, USA
| | - Gordon Andan
- Department of Surgery of Columbia University Medical Center, New York, NY, 10032, USA
| | - Piotr Witkowski
- Department of Surgery of Columbia University Medical Center, New York, NY, 10032, USA
- Dept of Surgery, Medical University of Gdansk, Poland
| | - Mark Hardy
- Department of Surgery of Columbia University Medical Center, New York, NY, 10032, USA
| | - Pasquale Barba
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Naples, 80131, Italy
| | - Caterina Ferrara
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Naples, 80131, Italy
| | - Antonella Maffei
- Department of Medicine of Columbia University Medical Center, New York, NY, 10032, USA
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Naples, 80131, Italy
| | - Matthew Freeby
- Department of Medicine of Columbia University Medical Center, New York, NY, 10032, USA
| | - Robin Goland
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY 10032, USA
| | - Rudolph L. Leibel
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY 10032, USA
| | - Ian Sweet
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Paul E. Harris
- Department of Medicine of Columbia University Medical Center, New York, NY, 10032, USA
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Harris PE, Ferrara C, Barba P, Polito T, Freeby M, Maffei A. VMAT2 gene expression and function as it applies to imaging beta-cell mass. J Mol Med (Berl) 2007; 86:5-16. [PMID: 17665159 DOI: 10.1007/s00109-007-0242-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/06/2007] [Accepted: 06/27/2007] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. The two main forms of the disease are distinguished by different pathogenesis, natural histories, and population distributions and indicated as either type 1 (T1DM) or type 2 diabetes mellitus (T2DM). It is well established that T1DM is an autoimmune disease whereby beta-cells of pancreatic islets are destroyed leading to loss of endogenous insulin production. Albeit less dramatic, beta-cell mass (BCM) also drops in T2DM. Therefore, it is realistic to expect that noninvasive measures of BCM might provide useful information in the diabetes-care field. Preclinical studies have demonstrated that BCM measurements by positron emission tomography scanning, using the vesicular monoamine transporter type 2 (VMAT2) as a tissue-specific surrogate marker of insulin production and [11C] Dihydrotetrabenazine (DTBZ) as the radioligand specific for this molecule, is feasible in animal models. Unfortunately, the mechanisms underlying beta-cell-specific expression of VMAT2 are still largely unexplored, and a much better understanding of the regulation of VMAT2 gene expression and of its function in beta-cells will be required before the full utility of this technique in the prediction and treatment of individuals with diabetes can be understood. In this review, we summarize much of what is understood about the regulation of VMAT2 and identify questions whose answers may help in understanding what measurements of VMAT2 density mean in the context of diabetes.
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Affiliation(s)
- Paul E Harris
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, CNR, Naples, Italy.
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Maffei A, Harris PE. Targeting vesicular monoamine transporter Type 2 for noninvasive PET-based β-cell mass measurements. Expert Rev Endocrinol Metab 2007; 2:35-46. [PMID: 30743747 DOI: 10.1586/17446651.2.1.35] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The common pathology in both Types 1 and 2 diabetes is insufficient β-cell mass to meet the metabolic needs of insulin production. The rising worldwide incidence of diabetes, combined with the lack of reliable endpoints of the body's true capacity to produce insulin, constitute a serious dilemma facing healthcare professionals and the pharmaceutical industry. Recent advances in imaging science and molecular imaging chemistry, as well as a broader understanding of basic islet biology, now allow the collection of quantitative information about β cells deep within the pancreas. The ability to noninvasively measure the mass of insulin-producing cells will most likely be of value towards characterizing new drugs and refining the diagnosis and treatment of this burdensome disease.
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Affiliation(s)
- Antonella Maffei
- a Research Scientist, IGB - CNR: Institute of Genetics and Biophysics, Adriano Buzzati-Traverso, Naples, 80131, Italy.
| | - Paul E Harris
- b Research Scientist, Columbia University Medical Center, Department of Medicine, BB 20-06, College of Physicians and Surgeons 650 West 168th Street, New York, NY, 10032, USA.
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Abstract
Atypical antipsychotic drugs have become the treatment of choice for psychotic disorders. However, these medications, though certainly superior in many respects to the more traditional medications, have been shown to have a number of untoward consequences. Understanding of the metabolic consequences of these medications is essential for the psychiatrist. The possible development of diabetes, weight gain, and hypertriglyceridemia in patients taking atypical antipsychotics makes it imperative that the prescribing physician regularly monitor patients on these agents. One possible monitoring scheme is outlined and recommendations for treatment are discussed.
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Affiliation(s)
- Harold E Lebovitz
- Department of Medicine, State University of New York Health Science Center at Brooklyn, USA.
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Hajduch E, Rencurel F, Balendran A, Batty IH, Downes CP, Hundal HS. Serotonin (5-Hydroxytryptamine), a novel regulator of glucose transport in rat skeletal muscle. J Biol Chem 1999; 274:13563-8. [PMID: 10224126 DOI: 10.1074/jbc.274.19.13563] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study we show that serotonin (5-hydroxytryptamine (5-HT)) causes a rapid stimulation in glucose uptake by approximately 50% in both L6 myotubes and isolated rat skeletal muscle. This activation is mediated via the 5-HT2A receptor, which is expressed in L6, rat, and human skeletal muscle. In L6 cells, expression of the 5-HT2A receptor is developmentally regulated based on the finding that receptor abundance increases by over 3-fold during differentiation from myoblasts to myotubes. Stimulation of the 5-HT2A receptor using methylserotonin (m-HT), a selective 5-HT2A agonist, increased muscle glucose uptake in a manner similar to that seen in response to 5-HT. The agonist-mediated stimulation in glucose uptake was attributable to an increase in the plasma membrane content of GLUT1, GLUT3, and GLUT4. The stimulatory effects of 5-HT and m-HT were suppressed in the presence of submicromolar concentrations of ketanserin (a selective 5-HT2A antagonist) providing further evidence that the increase in glucose uptake was specifically mediated via the 5-HT2A receptor. Treatment of L6 cells with insulin resulted in tyrosine phosphorylation of IRS1, increased cellular production of phosphatidylinositol 3,4,5-phosphate and a 41-fold activation in protein kinase B (PKB/Akt) activity. In contrast, m-HT did not modulate IRS1, phosphoinositide 3-kinase, or PKB activity. The present results indicate that rat and human skeletal muscle both express the 5-HT2A receptor and that 5-HT and specific 5-HT2A agonists can rapidly stimulate glucose uptake in skeletal muscle by a mechanism which does not depend upon components that participate in the insulin signaling pathway.
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Affiliation(s)
- E Hajduch
- Departments of Anatomy and Physiology, The University of Dundee, Dundee DD1 4HN, Scotland
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12
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Lindström P, Sehlin J. 5-hydroxytryptamine stimulates 86Rb+ efflux from pancreatic beta-cells. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 720:400-4. [PMID: 7052142 DOI: 10.1016/0167-4889(82)90118-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effects of 5-hydroxytryptamine and 5-hydroxytryptophan on 86Rb+ efflux from prelabelled ob/ob-mouse islets were studied to better understand the cellular mechanisms underlying the effects of 5-hydroxytryptamine and 5-hydroxytryptophan on insulin release. 5-Hydroxytryptophan (4 mM) had no effect on 86Rb+ efflux either at a low (3mM) or at a high (20 mM) D-glucose concentration, whereas 5-hydroxytryptamine (4 mM) stimulated 86Rb+ efflux at both glucose concentrations. These results indicate that 5-hydroxytryptamine may reduce glucose-induced insulin release by inhibiting early steps in the beta-cell stimulus-secretion coupling.
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13
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Benfenati F, Bernardi P, Cortelli P, Capelli M, Adani C, Calzà L, Agnati LF. Possible mixed agonist--antagonist activity of D-sulpiride at dopamine receptor level in man. Neurosci Lett 1981; 26:289-95. [PMID: 7033836 DOI: 10.1016/0304-3940(81)90147-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effects of different doses of D-sulpiride (1, 6, 12 and 25 mg, i.v.) on arterial blood pressure (ABP), heart rate (HR) and prolactin (PRL), growth hormone (GH), insulin and gastrin secretions have been studied in 8 normal men. D-Sulpiride increased systolic ABP with a maximum effect rather 12 mg i.v., while it had only slight effects on diastolic ABP and HR. PRL secretion was increased by D-sulpiride in a dose-dependent way, while insulin secretion was lowered and GH secretion slightly enhanced only in a restricted range of doses (6 mg and 12 mg i.v., respectively). Gastrin secretion seemed to be unaffected by D-sulpiride at any of the tested doses. These results are discussed in view of a possible mixed agonist--antagonist activity of D-sulpiride at dopamine receptor level in contrast with the relatively pure antagonistic action of the levo isomer.
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Zampa GA, Benfenati F, Ghisoli E, Corbucci G, Vecchi P, Zini I, Battistini N, Agnati LF. Neuroendocrine control of basal insulin secretion in man: a study with bromocriptine, clonidine and naloxone. J Endocrinol Invest 1981; 4:423-9. [PMID: 7037921 DOI: 10.1007/bf03348306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effects of bromocriptine (CB-154, 2.5 mg po), clonidine (0.05 mg im) and naloxone (0.4 mg im), as well as the interaction between naloxone and CB-154 or clonidine on basal insulin secretion were studied in 6 normal men. Clonidine, naloxone and CB-154 plus naloxone lowered insulin plasma levels; CB-154 alone caused only a slight reduction, whereas clonidine plus naloxone did not affect insulin secretion. These results prove the existence of a complex neuroendocrine control of basal insulin secretion through dopaminergic, adrenergic and opiate mechanisms; they also suggest that the opiate inhibitory control of insulin release may be dissociated from the dopaminergic one, but may interact with the adrenergic one.
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Lindström P. Further studies on 5-hydroxytryptamine transport in pancreatic islets and isolated beta-cells. Br J Pharmacol 1981; 73:385-91. [PMID: 7016232 PMCID: PMC2071649 DOI: 10.1111/j.1476-5381.1981.tb10433.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
1 The transport mechanism for (3)H-labelled 5-hydroxytryptamine (5-HT) in isolated pancreatic islets of non-inbred ob/ob mice was further characterized.2 Isolated beta-cells accumulated 5-HT to the same degree and with the same Na(+)-dependence as whole islets.3 Imipramine inhibited the uptake in a concentration-dependent way.4 Reserpine did not affect the uptake or efflux rates.5 Glucose stimulation of insulin secretion did not affect the uptake rate.6 It is concluded that the observed islet uptake of [(3)H]-5-HT represents an intracellular accumulation by the beta-cells. Mechanisms at the level of the plasma membrane may be rate-limiting for this process.
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Feldman JM, Vervaert C, Klatt C, Seigler HF. Therapy of malignant hamster insulinomas with monoamine precursors. Diabetologia 1981; 20:148-54. [PMID: 6259010 DOI: 10.1007/bf00262019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Lindström P, Sehlin J, Täljedal IB. Uptake mechanisms of 5-HT in pancreatic beta-cells. Ups J Med Sci 1981; 86:143-8. [PMID: 7034344 DOI: 10.3109/03009738109179222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Furman BL, Wilson GA. Further studies on the effects of 5-hydroxytryptophan on plasma glucose and insulin in the mouse. Diabetologia 1980; 19:386-90. [PMID: 7000601 DOI: 10.1007/bf00280525] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effects of 5-hydroxytryptophan on plasma concentrations of glucose and immunoreactive insulin were examined in conscious mice. Blood samples were obtained after anaesthetizing the mice lightly with ether at the desired time. Large doses of L-5-hydroxytryptophan (5HTP) (200-400 mg/kg IV) produced a dose-dependent hypoglycaemic response in fasted mice (e.g. control 5.7 +/- 0.2 mmol/l, 5HTP 400 mg/kg 2.6 +/- 0.3 mmol/l). This response was preceded by a significant elevation in the plasma immunoreactive insulin concentration (e.g. control 6 +/- 2 mU/l; 5HTP 400 mg/kg 53 +/- 7 mU/l). Induction of diabetes with alloxan (80 mg/kg IV 72 h previously) prevented the hypoglycaemic effect of 5HTP. Alloxan diabetes abolished the hyperinsulinaemic response to 100 mg/kg of 5HTP and reduced by 66% the response to 400 mg/kg of 5HTP. In alloxan diabetic mice 5HTP produced a marked hyperglycaemic response (control 17.9 +/- 2.0 mmol/l; 5HTP 100 mg/kg 36.1 +/- 2.3 mmol/l). In normal mice pre-treated with nialamide, a monoamine oxidase inhibitor, much lower doses of 5 HTP (5-10 mg/kg) were required to produce hypoglycaemia. There was no detectable elevation in the plasma insulin concentration accompanying the hypoglycaemic response to smaller doses of 5HTP in nialamide treated mice. The hyperinsulinaemic and hypoglycaemic actions of 5HTP in normal mice were prevented completely by pretreatment with benserazide, an inhibitor of aromatic amino acid decarboxylase. 5-hydroxytryptamine did not modify the plasma glucose concentration in either normal or nialamide-treated animals. It is concluded that the hypoglycaemic response to 5HTP in normal mice is mediated at least partly through an elevation in the plasma insulin concentration, although it is likely that additional mechanisms are involved.
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19
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Lindström P, Sehlin J, Täljedal IB. Characteristics of 5-hydroxytryptamine transport in pancreatic islets. Br J Pharmacol 1980; 68:773-8. [PMID: 6991048 PMCID: PMC2044246 DOI: 10.1111/j.1476-5381.1980.tb10871.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
1 Transmembrane transport of 3H-labelled 5-hydroxytryptamine (5-HT) by isolated pancreatic islets of non-inbred ob/ob mice was studied. 2 5-HT was vigorously accumulated in a temperature-dependent way by the islet cells. 3 Studies of the concentration-dependence of [3H]-5-HT uptake revealed complex kinetics with one component being saturated at 1 to 3 microM 5-HT (apparent association constant 0.6 x 10(6) M(-1) and the other non-saturated up to 1 mM 5-HT. 4 The saturable uptake was inhibited by Na+-deficiency and metabolic poisoning with 2,4-dinitrophenol and antimycin A, whereas the non-saturable component was not affected. 5 Omission of K+, Ca2+ or Mg2+ did not affect the uptake rate. 6 It is concluded that 5-HT is taken up by pancreatic beta-cells by mechanisms very similar to those observed in thrombocytes and neurones.
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20
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Mizoguchi H, Orlowski M, Wilk S, Green JP. gamma-Glutamyl DOPA and gamma-glutamyl dopamine: effect on plasma glucose levels. Eur J Pharmacol 1979; 57:239-45. [PMID: 488163 DOI: 10.1016/0014-2999(79)90371-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
gamma-Glutamyl-L-3,4-dihydroxyphenylalanine (gamma-glutamyl DOPA) and gamma-glutamyldopamine (gamma-glutamyl DA) are kidney specific prodrugs. Their effect on plasma glucose levels in the rat was compared to that of L-DOPA and dopamine (DA) after a 30 min intravenous infusion. L-DOPA and DA induced hyperglycemia after 15 min of druginfusion. A more marked and protracted elevation of plasma glucose was observed after infusion of gamma-glutamyl DA. By gamma-glutamyl DOPA had no effect on plasma glucose levels in spite of the high accumulation of DA in the pancreas after this prodrug. Of the various dopamine produrgs studied only gamma-glutamyl DOPA was not hyperglycemic in doses that are known to increase renal plasma flow in the rat. A simplified new procedure for the synthesis of gamma-glutamyl DA is described.
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Ferrari C, Barbieri C, Caldara R, Magnoni V, Testori GP, Romussi M. Improved oral glucose tolerance following antiserotonin treatment in patients with chemical diabetes. Eur J Clin Pharmacol 1979; 15:395-9. [PMID: 499287 DOI: 10.1007/bf00561737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effects of short-term treatment with either placebo or two serotonin antagonists, cyproheptadine and metergoline, on oral glucose tolerance and insulin secretion have been evaluated in normal subjects and in patients with chemical diabetes. Placebo treatment was not associated with any significant change in the parameters examined. Glucose tolerance in chemical diabetics was significantly improved both after cyproheptadine and metergoline; fasting plasma glucose was also reduced by metergoline. Treatment with the latter drug was also associated with a significant decrease in incremental glucose area in healthy subjects, which was not affected by cyproheptadine. Basal and glucose-stimulated insulin secretion were not affected by either drug in any subjects. Cyproheptadine and metergoline improve glucose metabolism in chemical diabetes probably by reducing insulin resistance. This may depend either on decreased secretion of counter-regulatory hormones or on a direct pharmacological action of the drugs on glucose utilization, possibly mediated by their common antiserotoninergic properties.
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Pulido OM, Bencosme SA, de Bold ML, de Bold AJ. Intracellular pancreatic B cell serotonin and the dynamics of insulin release. Diabetologia 1978; 15:197-204. [PMID: 359396 DOI: 10.1007/bf00421239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The role of intracellular pancreatic B cell serotonin in the dynamics of insulin release was investigated in an in situ perfused rat pancreas preparation. Animals were pretreated with 5-hydroxytryptophan (5-HTP) to increase the intracellular levels of serotonin (5-HT) as shown by fluorescence histochemistry. Despite a clear induction of intracellular 5-HT fluorescence in pancreatic islets neither the pattern nor the total amount of insulin released were significantly modified after perfusion with either glucose or tolbutamide. However, the L-amino acid decarboxylase inhibitor, RO 4--4602, significantly decreased both phases of glucose-mediated insulin release in normal animals as well as in those receiving 5-HTP.
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Ericson LE, Håkanson R, Lundquist I. Accumulation of dopamine in mouse pancreatic B-cells following injection of L-DOPA. Localization to secretory granules and inhibition of insulin secretion. Diabetologia 1977; 13:117-24. [PMID: 404204 DOI: 10.1007/bf00745138] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Accumulation and subcellular localization of dopamine (DA) in pancreatic B-cells and its effects on insulin secretion were investigated in mice following a single injection of L-3,4-dihydroxyphenylalanine (L-DOPA). Electron microscopic autoradiography showed that 3H-DA formed from administered 3H-DOPA was present over B-cells as well as over other types of islet cells. Pretreatment of the animals with a decarboxylase inhibitor greatly reduced the number of autoradiographic grains. In the B-cells the 3H-DA-grains were associated with the secretory granules. The location of the label may suggest an incorporation in the periphery of the beta-granule, rather than in the dense core, supposed to contain insulin. Accumulation of DA in the B-cells following L-DOPA administration was found to inhibit partially the insulin secretory response to different insulin secretagogues (glucose, glibenclamide and L-isopropylnoradrenaline (L-IPNA). Treatment with monoamine oxidase inhibitor + L-DOPA induced an almost total suppression of L-IPNA-stimulated insulin secretion, whereas glucose-induced insulin release was still only partially inhibited. Pretreatment with a decarboxylase inhibitor abolished the effects of L-DOPA. It is suggested that intracellularly accumulated DA in the B-cell exerts an inhibitory action on insulin releasing mechanisms induced by different secretagogues and that this action might involve interference with a calcium translocation process at the level of the secretory granule.
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