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Rodriguez-Diaz R, Tamayo A, Hara M, Caicedo A. The Local Paracrine Actions of the Pancreatic α-Cell. Diabetes 2020; 69:550-558. [PMID: 31882565 PMCID: PMC7085245 DOI: 10.2337/dbi19-0002] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 12/16/2019] [Indexed: 12/13/2022]
Abstract
Secretion of glucagon from the pancreatic α-cells is conventionally seen as the first and most important defense against hypoglycemia. Recent findings, however, show that α-cell signals stimulate insulin secretion from the neighboring β-cell. This article focuses on these seemingly counterintuitive local actions of α-cells and describes how they impact islet biology and glucose metabolism. It is mostly based on studies published in the last decade on the physiology of α-cells in human islets and incorporates results from rodents where appropriate. As this and the accompanying articles show, the emerging picture of α-cell function is one of increased complexity that needs to be considered when developing new therapies aimed at promoting islet function in the context of diabetes.
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Affiliation(s)
- Rayner Rodriguez-Diaz
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL
| | - Alejandro Tamayo
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL
| | - Manami Hara
- Department of Medicine, University of Chicago, Chicago, IL
| | - Alejandro Caicedo
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL
- Program in Neuroscience, University of Miami Miller School of Medicine, Miami, FL
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Abstract
Type 1 diabetes (T1D) patients who receive pancreatic islet transplant experience significant improvement in their quality-of-life. This comes primarily through improved control of blood sugar levels, restored awareness of hypoglycemia, and prevention of serious and potentially life-threatening diabetes-associated complications, such as kidney failure, heart and vascular disease, stroke, nerve damage, and blindness. Therefore, beta cell replacement through transplantation of isolated islets is an important option in the treatment of T1D. However, lasting success of this promising therapy depends on durable survival and efficacy of the transplanted islets, which are directly influenced by the islet isolation procedures. Thus, isolating pancreatic islets with consistent and reliable quality is critical in the clinical application of islet transplantation.Quality of isolated islets is important in pre-clinical studies as well, as efforts to advance and improve clinical outcomes of islet transplant therapy have relied heavily on animal models ranging from rodents, to pigs, to nonhuman primates. As a result, pancreatic islets have been isolated from these and other species and used in a variety of in vitro or in vivo applications for this and other research purposes. Protocols for islet isolation have been somewhat similar across species, especially, in mammals. However, given the increasing evidence about the distinct structural and functional features of human and mouse islets, using similar methods of islet isolation may contribute to inconsistencies in the islet quality, immunogenicity, and experimental outcomes. This may also contribute to the discrepancies commonly observed between pre-clinical findings and clinical outcomes. Therefore, it is prudent to consider the particular features of pancreatic islets from different species when optimizing islet isolation protocols.In this chapter, we explore the structural and functional features of pancreatic islets from mice, pigs, nonhuman primates, and humans because of their prevalent use in nonclinical, preclinical, and clinical applications.
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Chowdhury S, Wang S, Patterson BW, Reeds DN, Wice BM. The combination of GIP plus xenin-25 indirectly increases pancreatic polypeptide release in humans with and without type 2 diabetes mellitus. ACTA ACUST UNITED AC 2013; 187:42-50. [PMID: 24183983 DOI: 10.1016/j.regpep.2013.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/07/2013] [Accepted: 10/23/2013] [Indexed: 12/25/2022]
Abstract
Xenin-25 (Xen) is a 25-amino acid neurotensin-related peptide that activates neurotensin receptor-1 (NTSR1). We previously showed that Xen increases the effect of glucose-dependent insulinotropic polypeptide (GIP) on insulin release 1) in hyperglycemic mice via a cholinergic relay in the periphery independent from the central nervous system and 2) in humans with normal or impaired glucose tolerance, but not type 2 diabetes mellitus (T2DM). Since this blunted response to Xen defines a novel defect in T2DM, it is important to understand how Xen regulates islet physiology. On separate visits, subjects received intravenous graded glucose infusions with vehicle, GIP, Xen, or GIP plus Xen. The pancreatic polypeptide response was used as an indirect measure of cholinergic input to islets. The graded glucose infusion itself had little effect on the pancreatic polypeptide response whereas administration of Xen equally increased the pancreatic polypeptide response in humans with normal glucose tolerance, impaired glucose tolerance, and T2DM. The pancreatic polypeptide response to Xen was similarly amplified by GIP in all 3 groups. Antibody staining of human pancreas showed that NTSR1 is not detectable on islet endocrine cells, sympathetic neurons, blood vessels, or endothelial cells but is expressed at high levels on PGP9.5-positive axons in the exocrine tissue and at low levels on ductal epithelial cells. PGP9.5 positive nerve fibers contacting beta cells in the islet periphery were also observed. Thus, a neural relay, potentially involving muscarinic acetylcholine receptors, indirectly increases the effects of Xen on pancreatic polypeptide release in humans.
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Affiliation(s)
- Sara Chowdhury
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, Saint Louis, MO, United States
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Rodriguez-Diaz R, Abdulreda MH, Formoso AL, Gans I, Ricordi C, Berggren PO, Caicedo A. Innervation patterns of autonomic axons in the human endocrine pancreas. Cell Metab 2011; 14:45-54. [PMID: 21723503 PMCID: PMC3135265 DOI: 10.1016/j.cmet.2011.05.008] [Citation(s) in RCA: 242] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 03/30/2011] [Accepted: 05/05/2011] [Indexed: 11/18/2022]
Abstract
The autonomic nervous system regulates hormone secretion from the endocrine pancreas, the islets of Langerhans, thus impacting glucose metabolism. The parasympathetic and sympathetic nerves innervate the pancreatic islet, but the precise innervation patterns are unknown, particularly in human. Here we demonstrate that the innervation of human islets is different from that of mouse islets and does not conform to existing models of autonomic control of islet function. By visualizing axons in three dimensions and quantifying axonal densities and contacts within pancreatic islets, we found that, unlike mouse endocrine cells, human endocrine cells are sparsely contacted by autonomic axons. Few parasympathetic cholinergic axons penetrate the human islet, and the invading sympathetic fibers preferentially innervate smooth muscle cells of blood vessels located within the islet. Thus, rather than modulating endocrine cell function directly, sympathetic nerves may regulate hormone secretion in human islets by controlling local blood flow or by acting on islet regions located downstream.
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Affiliation(s)
- Rayner Rodriguez-Diaz
- Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Alpha cells secrete acetylcholine as a non-neuronal paracrine signal priming beta cell function in humans. Nat Med 2011; 17:888-92. [PMID: 21685896 PMCID: PMC3132226 DOI: 10.1038/nm.2371] [Citation(s) in RCA: 227] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 04/05/2011] [Indexed: 01/02/2023]
Abstract
Acetylcholine is a neurotransmitter that plays a major role in the function of the insulin secreting pancreatic beta cell1,2. Parasympathetic innervation of the endocrine pancreas, the islets of Langerhans, has been shown to provide cholinergic input to the beta cell in several species1,3,4, but the role of autonomic innervation in human beta cell function is at present unclear. Here we show that, in contrast to mouse islets, cholinergic innervation of human islets is sparse. Instead, we find that the alpha cells of the human islet provide paracrine cholinergic input to surrounding endocrine cells. Human alpha cells express the vesicular acetylcholine transporter and release acetylcholine when stimulated with kainate or a lowering in glucose concentration. Acetylcholine secretion by alpha cells in turn sensitizes the beta cell response to increases in glucose concentration. Our results demonstrate that in human islets acetylcholine is a paracrine signal that primes the beta cell to respond optimally to subsequent increases in glucose concentration. We anticipate these results to revise models about neural input and cholinergic signaling in the endocrine pancreas. Cholinergic signaling within the islet represents a potential therapeutic target in diabetes5, highlighting the relevance of this advance to future drug development.
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Immunohistochemical Study on the Innervation of the Chicken Pancreas by Pituitary Adenylate Cyclase-Activating Polypeptides (PACAPs)-Containing Nerves. J Poult Sci 2009. [DOI: 10.2141/jpsa.46.234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Krowicki ZK, Hornby PJ. The nucleus raphe obscurus controls pancreatic hormone secretion in the rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1995; 268:E1128-34. [PMID: 7611388 DOI: 10.1152/ajpendo.1995.268.6.e1128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Until recently, the dorsal vagal complex (DVC) was considered as the only brain stem regulatory center for the vagal control of the endocrine pancreas. Because the nucleus raphe obscurus (NRO) maintains anatomic connections via the DVC to the pancreas, a functional significance of these findings was investigated in the present study. Kainic acid and vehicle were microinjected into the right DVC and the NRO of alpha-chloralose-anesthetized rats, and plasma concentrations of rat insulin, glucagon, and glucose were determined before and 5, 15, 30, and 60 min after injections. Chemical stimulation of neurons in the DVC by kainic acid at a dose of 200 pmol evoked increases in concentrations of insulin, with a peak at 15 min, and glucagon, with a peak at 30 min. Microinjection of kainic acid into the NRO at a dose of 200 pmol, but not at a dose of 20 pmol, produced increases in plasma concentrations of insulin, with a peak at 30 min, and glucagon, with a peak at 60 min. Plasma glucose levels on microinjection of kainic acid into the NRO at a dose of 20 pmol were decreased, whereas no changes on microinjection of kainic acid at a dose of 200 pmol were observed. The effects of kainic acid on insulin and glucagon secretion in the NRO were abolished by bilateral vagotomy. The study demonstrates for the first time that the NRO can contribute to vagal control of pancreatic endocrine function, although the exact circuitry and neurotransmitters involved in this response remain unknown.
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Affiliation(s)
- Z K Krowicki
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Medical Center, New Orleans 70112, USA
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Madureira ML. Ultrastructural characterization of a regular schwann-axon-islet complex after the autograft of pancreatic fragments into the spleen of the adult dog. Cell Transplant 1994; 3:153-62. [PMID: 8012731 DOI: 10.1177/096368979400300203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
After autotransplantation of pancreatic fragments into the dog's spleen, the morphogenesis of the reinnervating process has evolved as an highly differentiated model, reproducing the most peculiar and systematic relationships between schwann cells, axons, and islet cells reported in the dog's islet, despite it's modulation by the restrictive conditions derived from the intrasplenic location of the dispersed pancreatic tissue. The reinnervating process is described, emphasizing the peculiar ultrastructural features and topography of the schwann cells and of the axonal network that impose the concept of a true anatomical reinnervation, which make previsible the possibility of a very selective and direct neurochemical and/or electrotonic control of the engrafted islet cells. The schwann-axon-islet complexes are a very peculiar and regular arrangement between islet cells and nervous elements and are reproduced after the autotransplant without the engrafted ganglia, whose potential but aleatory contribution could not be unequivocally characterized. Axonal profiles or schwann cells on the abundant regenerated ductal-acinar structures were not identified.
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Affiliation(s)
- M L Madureira
- Department of Surgery, University of Oporto School of Medicine, Portugal
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Ahrén B, Karlsson S, Lindskog S. Cholinergic regulation of the endocrine pancreas. PROGRESS IN BRAIN RESEARCH 1990; 84:209-18. [PMID: 1702544 DOI: 10.1016/s0079-6123(08)60905-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- B Ahrén
- Department of Pharmacology, Lund University, Sweden
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Otsuki M, Okabayashi Y, Nakamura T, Fujii M, Oka T, Tani S, Baba S. Inhibitory effects of pirenzepine on cholecystokinin and secretin stimulation on exocrine and endocrine rat pancreas. Dig Dis Sci 1987; 32:1136-44. [PMID: 2443324 DOI: 10.1007/bf01300201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Effects of pirenzepine, a newly developed anticholinergic drug, on exocrine and endocrine pancreatic functions stimulated by cholecystokinin octapeptide and secretin were studied in both isolated pancreatic acini and the isolated perfused pancreas of rats. In the isolated acini, pirenzepine did not have any significant effect on cholecystokinin-induced amylase release but caused an inhibition of amylase secretion initiated by secretin and shifted the dose-response curve for amylase secretion to the right. In the isolated perfused pancreas stimulated with 100 pM cholecystokinin octapeptide, addition of 10 microM pirenzepine before as well as after 20 min of perfusion significantly inhibited pancreatic juice flow but not enzyme output. In contrast, pirenzepine caused an inhibition of secretin-stimulated enzyme secretion, but not pancreatic juice flow. The stimulatory effect of both cholecystokinin octapeptide and secretin on insulin secretion was also inhibited by pirenzepine. The present data indicate that pirenzepine may have an influence on pancreatic exocrine and endocrine function by inhibiting endogenous cholinergic activity of the pancreas when a large dose is given.
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Affiliation(s)
- M Otsuki
- Second Department of Internal Medicine, Kobe University School of Medicine, Japan
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McCullough AJ, Marshall JB, Bingham CP, Rice BL, Manning LD, Kalhan SC. Carbachol modulates GIP-mediated insulin release from rat pancreatic lobules in vitro. THE AMERICAN JOURNAL OF PHYSIOLOGY 1985; 248:E299-303. [PMID: 3883800 DOI: 10.1152/ajpendo.1985.248.3.e299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Rat pancreatic lobules were used to investigate the interaction of gastric inhibitory polypeptide (GIP), carbachol, glucose, and an amino acid mixture on insulin secretion. At 5 mM glucose, GIP (1.1 ng/ml) did not augment insulin secretion in the presence or absence of carbachol (5 X 10(-5)M) during a 210-min incubation. However, at 11 mM glucose, GIP did augment insulin secretion in the presence (342.5 +/- 62.0 vs. 212.5 +/- 50.5 microU . ml-1 . mg tissue-1, mean +/- SE; P less than 0.01) but not the absence (217.0 +/- 45.5 vs. 205.8 +/- 35.0 microU . ml-1 . mg tissue-1) of carbachol. During subsequent 30-min incubations, GIP was increased to a supra-physiological concentration of 11 ng/ml and again augmented insulin secretion with (65.8 +/- 10.8 vs. 27.8 +/- 2.4 microU . ml-1 . mg tissue-1 . h-1; P less than 0.001) but not without (37.2 +/- 1.8 vs. 30.2 +/- 2 microU . ml-1 . mg-1 tissue-1 . h-1) carbachol present. This GIP-mediated insulin secretion was blocked by atropine (34.8 to 1.8 vs. 37.6 +/- 1.6 microU . ml-1 . mg tissue-1 . h-1). At amino acid concentrations of 21 and 211 mM, but not 2.1 mM, GIP augmented insulin release but again only with carbachol present. In conclusion, porcine GIP augments amino acid as well as glucose-mediated insulin secretion in vitro. Furthermore, this biological action is dependent on an, as yet, unidentified cholinergic mechanism. The pathophysiological significance of the neural-hormonal interaction deserves further investigation.
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