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Roberts FL, Cataldo LR, Fex M. Monoamines' role in islet cell function and type 2 diabetes risk. Trends Mol Med 2023; 29:1045-1058. [PMID: 37722934 DOI: 10.1016/j.molmed.2023.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/20/2023]
Abstract
The two monoamines serotonin and melatonin have recently been highlighted as potent regulators of islet hormone secretion and overall glucose homeostasis in the body. In fact, dysregulated signaling of both amines are implicated in β-cell dysfunction and development of type 2 diabetes mellitus (T2DM). Serotonin is a key player in β-cell physiology and plays a role in expansion of β-cell mass. Melatonin regulates circadian rhythm and nutrient metabolism and reduces insulin release in human and rodent islets in vitro. Herein, we focus on the role of serotonin and melatonin in islet physiology and the pathophysiology of T2DM. This includes effects on hormone secretion, receptor expression, genetic variants influencing β-cell function, melatonin treatment, and compounds that alter serotonin availability and signaling.
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Affiliation(s)
- Fiona Louise Roberts
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit for Molecular Metabolism, SE-21428 Malmö, Sweden
| | - Luis Rodrigo Cataldo
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit for Molecular Metabolism, SE-21428 Malmö, Sweden; The Novo Nordisk Foundation Centre for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, DK-2200, Denmark
| | - Malin Fex
- Lund University Diabetes Centre, Department of Clinical Sciences, Unit for Molecular Metabolism, SE-21428 Malmö, Sweden.
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Ramzy A, Edeer N, Baker RK, O’Dwyer S, Mojibian M, Verchere CB, Kieffer TJ. Insulin Null β-cells Have a Prohormone Processing Defect That Is Not Reversed by AAV Rescue of Proinsulin Expression. Endocrinology 2022; 163:6569864. [PMID: 35435956 PMCID: PMC9119694 DOI: 10.1210/endocr/bqac051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Indexed: 11/19/2022]
Abstract
Up to 6% of diabetes has a monogenic cause including mutations in the insulin gene, and patients are candidates for a gene therapy. Using a mouse model of permanent neonatal diabetes, we assessed the efficacy of an adeno-associated virus (AAV)-mediated gene therapy. We used AAVs with a rat insulin 1 promoter (Ins1) regulating a human insulin gene (INS; AAV Ins1-INS) or native mouse insulin 1 (Ins1; AAV Ins-Ins1) to deliver an insulin gene to β-cells of constitutive insulin null mice (Ins1-/-Ins2-/-) and adult inducible insulin-deficient mice [Ins1-/-Ins2f/f PdxCreER and Ins1-/-Ins2f/f mice administered AAV Ins1-Cre)]. Although AAV Ins1-INS could successfully infect and confer insulin expression to β-cells, insulin null β-cells had a prohormone processing defect. Secretion of abundant proinsulin transiently reversed diabetes. We reattempted therapy with AAV Ins1-Ins1, but Ins1-/-Ins2-/- β-cells still had a processing defect of both replaced Ins1 and pro-islet amyloid polypeptide (proIAPP). In adult inducible models, β-cells that lost insulin expression developed a processing defect that resulted in impaired proIAPP processing and elevated circulating proIAPP, and cells infected with AAV Ins1-Ins1 to rescue insulin expression secreted proinsulin. We assessed the subcellular localization of prohormone convertase 1/3 (PC1/3) and detected defective sorting of PC1/3 to glycogen-containing vacuoles and retention in the endoplasmic reticulum as a potential mechanism underlying defective processing. We provide evidence that persistent production of endogenous proinsulin within β-cells is necessary for β-cells to be able to properly store and process proinsulin.
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Affiliation(s)
- Adam Ramzy
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Nazde Edeer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Robert K Baker
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Shannon O’Dwyer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Majid Mojibian
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - C Bruce Verchere
- Department of Pathology and Laboratory Medicine, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Department of Surgery, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Correspondence: Timothy J. Kieffer, PhD, Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada.
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Linking hIAPP misfolding and aggregation with type 2 diabetes mellitus: a structural perspective. Biosci Rep 2022; 42:231205. [PMID: 35475576 PMCID: PMC9118370 DOI: 10.1042/bsr20211297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/12/2022] [Accepted: 04/26/2022] [Indexed: 11/17/2022] Open
Abstract
There are over 40 identified human disorders that involve certain proteins folding incorrectly, accumulating in the body causing damage to cells and organs and causing disease. Type 2 Diabetes Mellitus (T2DM) is one of these protein misfolding disorders (PMDs) and involves human islet amyloid polypeptide (hIAPP) misfolding and accumulating in parts of the body, primarily in the pancreas, causing damage to islet cells and affecting glucose regulation. In this review, we have summarised our current understanding of what causes hIAPP to misfold, what conformations are found in different parts of the body with a particular focus on what is known about the structure of hIAPP and how this links to T2DM. Understanding the molecular basis behind these misfolding events is essential for understanding the role of hIAPP to develop better therapeutics since type 2 diabetes currently affects over 4.9 million people in the United Kingdom alone and is predicted to increase as our population ages.
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Ling W, Huang YM, Qiao YC, Zhang XX, Zhao HL. Human Amylin: From Pathology to Physiology and Pharmacology. Curr Protein Pept Sci 2019; 20:944-957. [DOI: 10.2174/1389203720666190328111833] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 12/18/2022]
Abstract
The histopathological hallmark of type 2 diabetes is islet amyloid implicated in the developing treatment options. The major component of human islet amyloid is 37 amino acid peptide known as amylin or islet amyloid polypeptide (IAPP). Amylin is an important hormone that is co-localized, copackaged, and co-secreted with insulin from islet β cells. Physiologically, amylin regulates glucose homeostasis by inhibiting insulin and glucagon secretion. Furthermore, amylin modulates satiety and inhibits gastric emptying via the central nervous system. Normally, human IAPP is soluble and natively unfolded in its monomeric state. Pathologically, human IAPP has a propensity to form oligomers and aggregate. The oligomers show misfolded α-helix conformation and can further convert themselves to β-sheet-rich fibrils as amyloid deposits. The pathological findings and physiological functions of amylin have led to the introduction of pramlintide, an amylin analog, for the treatment of diabetes. The history of amylin’s discovery is a representative example of how a pathological finding can translate into physiological exploration and lead to pharmacological intervention. Understanding the importance of transitioning from pathology to physiology and pharmacology can provide novel insight into diabetes mellitus and Alzheimer's disease.
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Affiliation(s)
- Wei Ling
- Center for Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin 541004, China
| | - Yan-Mei Huang
- Center for Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin 541004, China
| | - Yong-Chao Qiao
- Department of Laboratory, the Affiliated Hospital of Guilin Medical University, Guilin 541004, China
| | - Xiao-Xi Zhang
- Center for Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin 541004, China
| | - Hai-Lu Zhao
- Center for Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin 541004, China
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Li N, Yang Z, Li Q, Yu Z, Chen X, Li JC, Li B, Ning SL, Cui M, Sun JP, Yu X. Ablation of somatostatin cells leads to impaired pancreatic islet function and neonatal death in rodents. Cell Death Dis 2018; 9:682. [PMID: 29880854 PMCID: PMC5992210 DOI: 10.1038/s41419-018-0741-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/20/2018] [Accepted: 05/22/2018] [Indexed: 02/08/2023]
Abstract
The somatostatin (SST)-secreting cells were mainly distributed in the pancreatic islets, brain, stomach and intestine in mammals and have many physiological functions. In particular, the SST-secreting δ cell is the third most common cell type in the islets of Langerhans. Recent studies have suggested that dysregulation of paracrine interaction between the pancreatic δ cells and β cells results in impaired glucose homeostasis and contributes to diabetes development. However, direct evidence of the functional importance of SST cells in glucose homeostasis control is still lacking. In the present study, we specifically ablated SST-secreting cells by crossing Sst-cre transgenic mice with R26 DTA mice (Sst Cre R26 DTA ). The Sst Cre R26 DTA mice exhibited neonatal death. The life spans of these mice with severe hypoglycemia were extended by glucose supplementation. Moreover, we observed that SST cells deficiency led to increased insulin content and excessive insulin release, which might contribute to the observed hypoglycemia. Unexpectedly, although SST is critical for the regulation of insulin content, factors other than SST that are produced by pancreatic δ cells via their endogenous corticotropin-releasing hormone receptor 2 (CRHR2) activity play the main roles in maintaining normal insulin release, as well as neonatal glucose homeostasis in the resting state. Taken together, our results identified that the SST cells in neonatal mouse played critical role in control of insulin release and normal islet function. Moreover, we provided direct in vivo evidence of the functional importance of the SST cells, which are essential for neonatal survival and the maintenance of glucose homeostasis.
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Affiliation(s)
- Na Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Zhao Yang
- Department of Biochemistry and Molecular Biology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Qing Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Zhen Yu
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Xu Chen
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Jia-Cheng Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Bo Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Shang-Lei Ning
- Department of General Surgery, Qilu Hospital Affiliated to Shandong University, Jinan, Shandong, 250012, China
| | - Min Cui
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Jin-Peng Sun
- Department of Biochemistry and Molecular Biology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China.,School of Medicine, Duke University, Durham, North Carolina, 27705, USA
| | - Xiao Yu
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China.
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Abels M, Riva M, Bennet H, Ahlqvist E, Dyachok O, Nagaraj V, Shcherbina L, Fred RG, Poon W, Sörhede-Winzell M, Fadista J, Lindqvist A, Kask L, Sathanoori R, Dekker-Nitert M, Kuhar MJ, Ahrén B, Wollheim CB, Hansson O, Tengholm A, Fex M, Renström E, Groop L, Lyssenko V, Wierup N. CART is overexpressed in human type 2 diabetic islets and inhibits glucagon secretion and increases insulin secretion. Diabetologia 2016; 59:1928-37. [PMID: 27338624 DOI: 10.1007/s00125-016-4020-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/23/2016] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS Insufficient insulin release and hyperglucagonaemia are culprits in type 2 diabetes. Cocaine- and amphetamine-regulated transcript (CART, encoded by Cartpt) affects islet hormone secretion and beta cell survival in vitro in rats, and Cart (-/-) mice have diminished insulin secretion. We aimed to test if CART is differentially regulated in human type 2 diabetic islets and if CART affects insulin and glucagon secretion in vitro in humans and in vivo in mice. METHODS CART expression was assessed in human type 2 diabetic and non-diabetic control pancreases and rodent models of diabetes. Insulin and glucagon secretion was examined in isolated islets and in vivo in mice. Ca(2+) oscillation patterns and exocytosis were studied in mouse islets. RESULTS We report an important role of CART in human islet function and glucose homeostasis in mice. CART was found to be expressed in human alpha and beta cells and in a subpopulation of mouse beta cells. Notably, CART expression was several fold higher in islets of type 2 diabetic humans and rodents. CART increased insulin secretion in vivo in mice and in human and mouse islets. Furthermore, CART increased beta cell exocytosis, altered the glucose-induced Ca(2+) signalling pattern in mouse islets from fast to slow oscillations and improved synchronisation of the oscillations between different islet regions. Finally, CART reduced glucagon secretion in human and mouse islets, as well as in vivo in mice via diminished alpha cell exocytosis. CONCLUSIONS/INTERPRETATION We conclude that CART is a regulator of glucose homeostasis and could play an important role in the pathophysiology of type 2 diabetes. Based on the ability of CART to increase insulin secretion and reduce glucagon secretion, CART-based agents could be a therapeutic modality in type 2 diabetes.
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Affiliation(s)
- Mia Abels
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Matteo Riva
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Hedvig Bennet
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Emma Ahlqvist
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Oleg Dyachok
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
| | - Vini Nagaraj
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Liliya Shcherbina
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Rikard G Fred
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Wenny Poon
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | | | - Joao Fadista
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Andreas Lindqvist
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Lena Kask
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Ramasri Sathanoori
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | | | - Michael J Kuhar
- The Yerkes Research Center of Emory University, Atlanta, GA, USA
| | - Bo Ahrén
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, University Medical Centre, Geneva, Switzerland
| | - Ola Hansson
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Anders Tengholm
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
| | - Malin Fex
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Erik Renström
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Leif Groop
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Valeriya Lyssenko
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
- Steno Diabetes Center A/S, Gentofte, Denmark
| | - Nils Wierup
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden.
- Lund University Diabetes Centre, Skåne University Hospital, Department of Clinical Sciences in Malmö, Unit of Neuroendocrine Cell Biology, Lund University, Clinical Research Centre 91:12, Jan Waldenströms gata 35, 20502, Malmö, Sweden.
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Comprehensive alpha, beta and delta cell transcriptomes reveal that ghrelin selectively activates delta cells and promotes somatostatin release from pancreatic islets. Mol Metab 2016; 5:449-458. [PMID: 27408771 PMCID: PMC4921781 DOI: 10.1016/j.molmet.2016.04.007] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/14/2016] [Accepted: 04/21/2016] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE Complex local crosstalk amongst endocrine cells within the islet ensures tight coordination of their endocrine output. This is illustrated by the recent demonstration that the negative feedback control by delta cells within pancreatic islets determines the homeostatic set-point for plasma glucose during mouse postnatal development. However, the close association of islet endocrine cells that facilitates paracrine crosstalk also complicates the distinction between effects mediated directly on beta cells from indirect effects mediated via local intermediates, such as somatostatin from delta cells. METHODS To resolve this problem, we generated reporter mice that allow collection of pure pancreatic delta cells along with alpha and beta cells from the same islets and generated comprehensive transcriptomes for each islet endocrine cell type. These transcriptomes afford an unparalleled view of the receptors expressed by delta, alpha and beta cells, and allow the prediction of which signal targets which endocrine cell type with great accuracy. RESULTS From these transcriptomes, we discovered that the ghrelin receptor is expressed exclusively by delta cells within the islet, which was confirmed by fluorescent in situ hybridization and qPCR. Indeed, ghrelin increases intracellular calcium in delta cells in intact mouse islets, measured by GCaMP6 and robustly potentiates glucose-stimulated somatostatin secretion on mouse and human islets in both static and perfusion assays. In contrast, des-acyl-ghrelin at the same dose had no effect on somatostatin secretion and did not block the actions of ghrelin. CONCLUSIONS These results offer a straightforward explanation for the well-known insulinostatic actions of ghrelin. Rather than engaging beta cells directly, ghrelin engages delta cells to promote local inhibitory feedback that attenuates insulin release. These findings illustrate the power of our approach to resolve some of the long-standing conundrums with regard to the rich feedback that occurs within the islet that is integral to islet physiology and therefore highly relevant to diabetes.
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Riva M, Nitert MD, Voss U, Sathanoori R, Lindqvist A, Ling C, Wierup N. Nesfatin-1 stimulates glucagon and insulin secretion and beta cell NUCB2 is reduced in human type 2 diabetic subjects. Cell Tissue Res 2011; 346:393-405. [DOI: 10.1007/s00441-011-1268-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 10/20/2011] [Indexed: 12/15/2022]
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Landerholm K, Falkmer SE, Järhult J, Sundler F, Wierup N. Cocaine- and amphetamine-regulated transcript in neuroendocrine tumors. Neuroendocrinology 2011; 94:228-36. [PMID: 21832817 DOI: 10.1159/000329044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 05/05/2011] [Indexed: 01/28/2023]
Abstract
BACKGROUND/AIMS Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic regulatory peptide highly expressed in the brain's appetite control centers, but also in peripheral neurons and in endocrine cells in the adrenal medulla, thyroid, pancreatic islets, and in the gastrointestinal tract. Plasma levels of CART were recently shown to be elevated in patients with neuroendocrine tumors (NETs), but the cellular sources of CART in NETs have remained unknown. The aim of the study was to establish whether CART is expressed in various types of NETs and, if so, to examine the frequency, distribution and phenotype of CART-expressing cells. METHODS Tumor specimens from 133 NETs originating in the stomach, ileum, rectum, pancreas and thyroid were examined with immunohistochemistry and in situ hybridization. The expression of CART was quantified and the CART-expressing cells were phenotyped by double staining for established markers and hormones. RESULTS CART-expressing tumor cells were found in the majority of the examined NETs. The expression pattern of CART was highly heterogeneous not only between tumors, but also within individual tumors. In 14% of the NETs, CART was found in a major population of the tumor cells. CONCLUSION CART is produced in the majority of NETs, regardless of tumor origin. This likely explains the elevated levels of circulating CART in certain NETs patients, as recently described. CART could therefore prove to be a useful tool in the diagnostics of NETs not only in blood samples, but also in histopathological specimens.
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Apelin is a novel islet peptide. ACTA ACUST UNITED AC 2010; 162:44-51. [PMID: 20346374 DOI: 10.1016/j.regpep.2010.03.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 03/09/2010] [Accepted: 03/16/2010] [Indexed: 11/22/2022]
Abstract
Apelin, a recently discovered peptide with wide tissue distribution, regulates feeding behavior, improves glucose utilization, and inhibits insulin secretion. We examined whether apelin is expressed in human islets, as well as in normal and type 2 diabetic (T2D) animal islets. Further, we studied islet apelin regulation and the effect of apelin on insulin secretion. Apelin expression and regulation was examined in human and animal specimens using immunocytochemistry, in situ hybridization, and real-time PCR. Insulin secretion was studied in INS-1 (832/13) clonal beta cells. APJ-receptor expression was studied using real-time PCR. In human and murine islets apelin was predominantly expressed in beta cells and alpha cells; a subpopulation of the PP cells in human islets also harbored apelin. In porcine and feline islets apelin was mainly expressed in beta cells. APJ-receptor expression was detected in INS-1 (832/13) cells, and in human and mouse islets. A high dose (1microM) of apelin-36 caused a moderate increase in glucose-stimulated insulin secretion (30%; p<0.001), while lower concentrations (10-100nM) of apelin robustly reduced insulin secretion by 50% (p<0.001). Apelin was upregulated in beta cells of T2D db/db mice (47% vs. controls; p<0.02) and GK-rats (74% vs. controls; p<0.002), but human islet apelin expression was unaffected by glucose. On the other hand, human islet apelin expression was diminished after culture in glucocorticoids (16% vs. controls; p<0.01). We conclude that apelin is a novel insulin-regulating islet peptide in humans and several laboratory animals. Islet apelin expression is negatively regulated by glucocorticoids, and upregulated in T2D animals. The presence of apelin receptors in islets suggests a role for apelin as a paracrine or autocrine messenger within the islets.
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The role of rosiglitazone treatment in the modulation of islet hormones and hormone-like peptides: a combined in situ hybridization and immunohistochemical study. J Mol Histol 2008; 39:635-42. [DOI: 10.1007/s10735-008-9204-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 10/20/2008] [Indexed: 10/21/2022]
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Islet beta-cell area and hormone expression are unaltered in Huntington's disease. Histochem Cell Biol 2008; 129:623-9. [PMID: 18259770 DOI: 10.1007/s00418-008-0393-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2008] [Indexed: 02/05/2023]
Abstract
Neurodegenerative disorders are often associated with metabolic alterations. This has received little attention, but might be clinically important because it can contribute to symptoms and influence the course of the disease. Patients with Huntington's disease (HD) exhibit increased incidence of diabetes mellitus (DM). This is replicated in mouse models of HD, e.g., the R6/2 mouse, in which DM is primarily caused by a deficiency of beta-cells with impaired insulin secretion. Pancreatic tissue from HD patients has previously not been studied and, thus, the pathogenesis of DM in HD is unclear. To address this issue, we examined pancreatic tissue sections from HD patients at different disease stages. We found that the pattern of insulin immunostaining, levels of insulin transcripts and islet beta-cell area were similar in HD patients and controls. Further, there was no sign of amyloid deposition in islets from HD patients. Thus, our data show that pancreatic islets in HD patients appear histologically normal. Functional studies of HD patients with respect to insulin secretion and islet function are required to elucidate the pathogenesis of DM in HD. This may lead to a better understanding of HD and provide novel therapeutic targets for symptomatic treatment in HD.
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Wierup N, Björkqvist M, Weström B, Pierzynowski S, Sundler F, Sjölund K. Ghrelin and motilin are cosecreted from a prominent endocrine cell population in the small intestine. J Clin Endocrinol Metab 2007; 92:3573-81. [PMID: 17595255 DOI: 10.1210/jc.2006-2756] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
CONTEXT Ghrelin is a novel hormone produced mainly in the gastric body. Hitherto, mapping studies of ghrelin cells covering the entire gastrointestinal (GI) tract in humans have been lacking. Furthermore, the phenotype of extragastric ghrelin cells is not known. OBJECTIVE The objective of the study was to perform a detailed mapping with specimens from all parts of the GI tract, and colocalization studies to phenotype ghrelin cells along the tract. In addition, mapping of ghrelin cells was performed in porcine GI tract, and the plasma profiles of ghrelin and motilin in blood from the porcine intestine were measured. DESIGN Biopsies from patients were obtained during gastroscopy or surgery. Ghrelin cell density and phenotyping was assessed with immunocytochemistry, in situ hybridization, and immunogold electron microscopy. Plasma ghrelin and motilin levels were measured in pigs, fitted with cannulas in the mesenteric vein. RESULTS The upper small intestine is unexpectedly rich in ghrelin cells, and these cells contribute to circulating ghrelin. Ghrelin and motilin are coproduced in the same cells in the duodenum and jejunum of both species, and ghrelin and motilin are stored in all secretory granules of such cells in humans, indicating cosecretion. The plasma profiles of ghrelin and motilin in pig were parallel, and a correlation between ghrelin and motilin (r(2) = 0.22; P < 0.001) was evident in intestinal blood. CONCLUSIONS The upper small intestine is an important source of ghrelin. The likely cosecretion of intestinal ghrelin and motilin suggests concerted actions of the two hormones. These data may have implications for understanding gut motility and clinical implications for dysmotility and bariatric surgery.
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Affiliation(s)
- Nils Wierup
- Lund University, Department of Experimental Medical Science, Division of Diabetes, Metabolism, and Endocrinology, Unit of Neuroendocrine Cell Biology, BMC B11, SE-22 184 Lund, Sweden.
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Wierup N, Björkqvist M, Kuhar MJ, Mulder H, Sundler F. CART regulates islet hormone secretion and is expressed in the beta-cells of type 2 diabetic rats. Diabetes 2006; 55:305-11. [PMID: 16443761 DOI: 10.2337/diabetes.55.02.06.db04-1383] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide widely expressed in the central, peripheral, and enteric nervous systems. CART is also expressed in endocrine cells, including beta-cells during rat development and delta-cells of adult rats. We examined the effect of CART 55-102 on islet hormone secretion, using INS-1(832/13) cells and isolated rat islets. In addition, islet CART expression was examined in two rat models of type 2 diabetes: Goto-Kakizaki (GK) rats and dexamethasone (DEX)-treated rats. At high glucose, CART potentiated cAMP-enhanced insulin secretion via the cAMP/protein kinase A-dependent pathway. In the absence of cAMP-elevating agents, CART was without effect on INS-1 cells but modestly inhibited secretion of insulin, glucagon, and somatostatin from isolated islets. CART was markedly upregulated in the beta-cells of both diabetes models. Thus, in DEX-treated rats, islet CART mRNA expression, and the number of CART-immunoreactive beta-cells were 10-fold higher than in control rats. In GK rats, the relative number of CART-expressing beta-cells was 30-fold higher than in control rats. We conclude that CART is a regulator of islet hormone secretion and that CART is upregulated in the beta-cells of type 2 diabetic rats.
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Affiliation(s)
- Nils Wierup
- Department of Experimental Medical Science, Division of Diabetes, Metabolism, and Endocrinology, Lund University, Sweden.
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15
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Lindqvist A, Mei J, Sundler F, Erlanson-Albertsson C. Decreased UCP2 mRNA expression in rat stomach following vagotomy: novel role for UCP2 as free radical scavenger in the stomach? Nutr Neurosci 2005; 7:217-22. [PMID: 15682648 DOI: 10.1080/10284150400011390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Uncoupling protein 2 (UCP2) is a protein, located in the inner mitochondrial membrane, which dissipates the proton gradient of this membrane and uncouples respiration from oxidative phosphorylation. We found, by in situ hybridisation, UCP2 mRNA to be located in the proliferating zone of the mucous neck cells in the fundus part of the rat stomach. We also found that UCP2 expression in fundus was significantly decreased after seven days of vagotomy. Furthermore, we found manganese-containing superoxide dismutase (SOD2), in fundus, to be down-regulated in a way similar to UCP2. The amount of ATP was significantly decreased following vagotomy. It is concluded that UCP2 in the gastro-intestinal tract is regulated through vagal innervation and suggested to act as a free radical scavenger.
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Affiliation(s)
- Andreas Lindqvist
- Department of Cell and Molecular Biology, Faculty of Medicine, University of Lund, BMC, SE-221 84 Lund, Sweden
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16
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Björkqvist M, Fex M, Renström E, Wierup N, Petersén A, Gil J, Bacos K, Popovic N, Li JY, Sundler F, Brundin P, Mulder H. The R6/2 transgenic mouse model of Huntington's disease develops diabetes due to deficient beta-cell mass and exocytosis. Hum Mol Genet 2005; 14:565-74. [PMID: 15649949 DOI: 10.1093/hmg/ddi053] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diabetes frequently develops in Huntington's disease (HD) patients and in transgenic mouse models of HD such as the R6/2 mouse. The underlying mechanisms have not been clarified. Elucidating the pathogenesis of diabetes in HD would improve our understanding of the molecular mechanisms involved in HD neuropathology. With this aim, we examined our colony of R6/2 mice with respect to glucose homeostasis and islet function. At week 12, corresponding to end-stage HD, R6/2 mice were hyperglycemic and hypoinsulinemic and failed to release insulin in an intravenous glucose tolerance test. In vitro, basal and glucose-stimulated insulin secretion was markedly reduced. Islet nuclear huntingtin inclusions increased dramatically over time, predominantly in beta-cells. beta-cell mass failed to increase normally with age in R6/2 mice. Hence, at week 12, beta-cell mass and pancreatic insulin content in R6/2 mice were 35+/-5 and 16+/-3% of that in wild-type mice, respectively. The normally occurring replicating cells were largely absent in R6/2 islets, while no abnormal cell death could be detected. Single cell patch-clamp experiments revealed unaltered electrical activity in R6/2 beta-cells. However, exocytosis was virtually abolished in beta- but not in alpha-cells. The blunting of exocytosis could be attributed to a 96% reduction in the number of insulin-containing secretory vesicles. Thus, diabetes in R6/2 mice is caused by a combination of deficient beta-cell mass and disrupted exocytosis.
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17
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Moesgaard SG, Ahrén B, Carr RD, Gram DX, Brand CL, Sundler F. Effects of high-fat feeding and fasting on ghrelin expression in the mouse stomach. ACTA ACUST UNITED AC 2005; 120:261-7. [PMID: 15177945 DOI: 10.1016/j.regpep.2004.03.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Revised: 03/18/2004] [Accepted: 03/26/2004] [Indexed: 10/26/2022]
Abstract
Ghrelin is a peptide identified as an endogenous ligand for the growth hormone secretagogue receptor. Studies have shown that ghrelin stimulates growth hormone, promotes food intake and decreases energy expenditure. Furthermore, feeding status seems to influence plasma ghrelin levels, as these are increased during fasting, whereas feeding and oral glucose intake reduce plasma ghrelin. This study examined whether standardized obesity and fasting affect cellular expression of ghrelin. Specimens from the gastrointestinal tract of fed or 18-h fasted, low-fat or high-fat fed (10 weeks on diet) C57BL/6J mice were studied by immunocytochemistry (ICC) for ghrelin and in situ hybridization (ISH) for ghrelin mRNA. Ghrelin was expressed in especially the corpus but also the antrum of the stomach of all groups studied. Cells positive for ghrelin and ghrelin mRNA in the stomach were reduced in high-fat fed mice. In contrast, ghrelin expression was not affected by fasting. The reduction in ghrelin expression in the high-fat fed mice was associated with a reduction in plasma levels of ghrelin, whereas after fasting, when expression rate was not altered, there was an increase in plasma ghrelin. In conclusion, ghrelin is highly expressed in the corpus and antrum of the stomach of C57BL/6J mice. This expression is reduced in obesity, whereas fasting has no effect.
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18
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Abstract
Amylin and insulin are co-localized within the same secretory granules of pancreatic beta-cells. Acutely, the secreted ratio of amylin:insulin is comparatively invariant, but long-standing hyperglycemia may favor induction of amylin synthesis and secretion over that of insulin. Amylin is also found in much lesser quantities in the gut and other tissues. In humans, both type 1 diabetes mellitus and the later stages of type 2 diabetes mellitus are characterized by deficiency of both insulin and amylin secretion. The severity of amylin deficiency appears to correlate with the severity of insulin deficiency. This concordance of deficiencies in amylin and insulin secretion observed with the progression of diabetes mellitus is consistent with their co-localization in pancreatic beta-cells. Amylin is cleared mainly by proteolytic degradation at the kidney. The terminal t1/2 for rat amylin in rats is approximately 13 min, and that for pramlintide in humans is approximately 20-45 min.
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Affiliation(s)
- Andrew Young
- Amylin Pharmaceuticals, Inc., San Diego, California, USA
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19
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Wierup N, Yang S, McEvilly RJ, Mulder H, Sundler F. Ghrelin is expressed in a novel endocrine cell type in developing rat islets and inhibits insulin secretion from INS-1 (832/13) cells. J Histochem Cytochem 2004; 52:301-10. [PMID: 14966197 DOI: 10.1177/002215540405200301] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ghrelin is produced mainly by endocrine cells in the stomach and is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R). It also influences feeding behavior, metabolic regulation, and energy balance. It affects islet hormone secretion, and expression of ghrelin and GHS-R in the pancreas has been reported. In human islets, ghrelin expression is highest pre- and neonatally. We examined ghrelin and GHS-R in rat islets during development with immunocytochemistry and in situ hybridization. We also studied the effect of ghrelin on insulin secretion from INS-1 (832/13) cells and the expression of GHS-R in these cells. We found ghrelin expression in rat islet endocrine cells from mid-gestation to 1 month postnatally. Islet expression of GHS-R mRNA was detected from late fetal stages to adult. The onset of islet ghrelin expression preceded that of gastric ghrelin. Islet ghrelin cells constitute a separate and novel islet cell population throughout development. However, during a short perinatal period a minor subpopulation of the ghrelin cells co-expressed glucagon or pancreatic polypeptide. Markers for cell lineage, proliferation, and duct cells revealed that the ghrelin cells proliferate, originate from duct cells, and share lineage with glucagon cells. Ghrelin dose-dependently inhibited glucose-stimulated insulin secretion from INS-1 (832/13) cells, and GHS-R was detected in the cells. We conclude that ghrelin is expressed in a novel developmentally regulated endocrine islet cell type in the rat pancreas and that ghrelin inhibits glucose-stimulated insulin secretion via a direct effect on the beta-cell.
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Affiliation(s)
- N Wierup
- Department of Physiological Science, Lund University, Lund, Sweden.
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20
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Wierup N, Kuhar M, Nilsson BO, Mulder H, Ekblad E, Sundler F. Cocaine- and amphetamine-regulated transcript (CART) is expressed in several islet cell types during rat development. J Histochem Cytochem 2004; 52:169-77. [PMID: 14729868 DOI: 10.1177/002215540405200204] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide widely expressed in the central and peripheral, including the enteric, nervous systems. CART is also expressed in pituitary endocrine cells, adrenomedullary cells, islet somatostatin cells, and in rat antral gastrin cells. We used immunocytochemistry (IHC) and in situ hybridization (ISH) to study CART expression in developing rat pancreas. We also examined co-expression of CART and islet hormones and developmental markers and the effect of CART on proliferation using clonal insulin cells (INS-1 832/13). A major portion of each of the islet cell types, except the ghrelin cells, expressed CART during a period before and around birth. Two weeks postnatally, CART expression was restricted to somatostatin cells. Pre- and early postnatally, many of the CART-expressing cells co-expressed cytokeratin 20 (CK20), a marker of duct cells and islet precursor cells, the trophic hormone gastrin, and a smaller subpopulation also harbored the proliferation marker Ki67. CART was also expressed in pancreatic nerve fibers, both sensory and autonomic, and in ganglion nerve cell bodies. Although highly expressed in the developing islets, CART did not affect proliferation of INS-1 cells. We have demonstrated that CART is expressed in several islet cell types during rat development but is restricted to somatostatin cells and neurons in the adult rat.
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Affiliation(s)
- N Wierup
- Department of Physiological Sciences, Section of Neuroendocrine Cell Biology, Lund University, Lund, Sweden.
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21
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Beales ILP, Calam J. Regulation of amylin release from cultured rabbit gastric fundic mucosal cells. BMC PHYSIOLOGY 2003; 3:13. [PMID: 14572315 PMCID: PMC269984 DOI: 10.1186/1472-6793-3-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Accepted: 10/22/2003] [Indexed: 11/21/2022]
Abstract
Background Amylin (islet amyloid polypeptide) is a hormone with suggested roles in the regulation of glucose homeostasis, gastric motor and secretory function and gastroprotection. In the gastric mucosa amylin is found co-localised with somatostatin in D-cells. The factors regulating gastric amylin release are unknown. In this study we have investigated the regulation of amylin release from gastric mucosal cells in primary culture. Rabbit fundic mucosal cells enriched for D-cells by counterflow elutriation were cultured for 40 hours. Amylin and somatostatin release over 2 hours in response to agonists were assessed. Results Amylin release was significantly enhanced by activation of protein kinase C with phorbol-12-myristate-13-acetate, adenylate cyclase with forskolin and elevation of intracellular calcium with A23187. Cholecystokinin (CCK), epinephrine and glucagon-like peptide-1 (GLP-1) each stimulated amylin release in a dose-dependent manner. Maximal CCK-stimulated release was greater than either epinephrine or GLP-1, even when the effects of the latter two were enhanced by isobutylmethylxanthine. Stimulated amylin release was significantly inhibited by carbachol (by 51–59%) and octreotide (by 33–42%). Somatostatin release paralleled that of amylin. Conclusions The cultured D-cell model provides a means of studying amylin release. Amylin secretion is stimulated by receptor-dependent and -independent activation of Ca2+/protein kinase C and adenylate cyclase pathways. Inhibition involves activation of muscarinic receptors and auto-regulation by somatostatin.
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Affiliation(s)
- Ian LP Beales
- Gastrointestinal Research Unit, Department of Physiology and Cell Biology, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, United Kingdom
- Department of Gastroenterology, Norfolk and Norwich University Hospital NHS Trust, Norwich NR4 7UZ, United Kingdom
| | - John Calam
- Department of Medicine, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom
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Mulder H, Sörhede-Winzell M, Contreras JA, Fex M, Ström K, Ploug T, Galbo H, Arner P, Lundberg C, Sundler F, Ahrén B, Holm C. Hormone-sensitive lipase null mice exhibit signs of impaired insulin sensitivity whereas insulin secretion is intact. J Biol Chem 2003; 278:36380-8. [PMID: 12835327 DOI: 10.1074/jbc.m213032200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Lipid metabolism plays an important role in glucose homeostasis under normal and pathological conditions. In adipocytes, skeletal muscle, and pancreatic beta-cells, lipids are mobilized from acylglycerides by the hormone-sensitive lipase (HSL). Here, the consequences of a targeted disruption of the HSL gene for glucose homeostasis were examined. HSL null mice were slightly hyperglycemic in the fasted, but not fed state, which was accompanied by moderate hyperinsulinemia. During glucose challenges, however, disposal of the sugar was not affected in HSL null mice, presumably because of release of increased amounts of insulin. Impaired insulin sensitivity was further indicated by retarded glucose disposal during an insulin tolerance test. A euglycemic hyperinsulinemic clamp revealed that hepatic glucose production was insufficiently blocked by insulin in HSL null mice. In vitro, insulin-stimulated glucose uptake into soleus muscle, and lipogenesis in adipocytes were moderately reduced, suggesting additional sites of insulin resistance. Morphometric analysis of pancreatic islets revealed a doubling of beta-cell mass in HSL null mice, which is consistent with an adaptation to insulin resistance. Insulin secretion in vitro, examined by perifusion of isolated islets, was not impacted by HSL deficiency. Thus, HSL deficiency results in a moderate impairment of insulin sensitivity in multiple target tissues of the hormone but is compensated by hyperinsulinemia.
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Affiliation(s)
- Hindrik Mulder
- Department of Cell and Molecular Biology, Physiological Sciences, and Medicine, Lund University, SE-221 84 Lund, Sweden.
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Winzell MS, Svensson H, Enerbäck S, Ravnskjaer K, Mandrup S, Esser V, Arner P, Alves-Guerra MC, Miroux B, Sundler F, Ahrén B, Holm C. Pancreatic beta-cell lipotoxicity induced by overexpression of hormone-sensitive lipase. Diabetes 2003; 52:2057-65. [PMID: 12882923 DOI: 10.2337/diabetes.52.8.2057] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Lipid perturbations associated with triglyceride overstorage in beta-cells impair insulin secretion, a process termed lipotoxicity. To assess the role of hormone-sensitive lipase, which is expressed and enzymatically active in beta-cells, in the development of lipotoxicity, we generated transgenic mice overexpressing hormone-sensitive lipase specifically in beta-cells. Transgenic mice developed glucose intolerance and severely blunted glucose-stimulated insulin secretion when challenged with a high-fat diet. As expected, both lipase activity and forskolin-stimulated lipolysis was increased in transgenic compared with wild-type islets. This was reflected in significantly lower triglycerides levels in transgenic compared with wild-type islets in mice receiving the high-fat diet, whereas no difference in islet triglycerides was found between the two genotypes under low-fat diet conditions. Our results highlight the importance of mobilization of the islet triglyceride pool in the development of beta-cell lipotoxicity. We propose that hormone-sensitive lipase is involved in mediating beta-cell lipotoxicity by providing ligands for peroxisome proliferator-activated receptors and other lipid-activated transcription factors, which in turn alter the expression of critical genes. One such gene might be uncoupling protein-2, which was found to be upregulated in transgenic islets, a change that was accompanied by decreased ATP levels.
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24
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Wierup N, Svensson H, Mulder H, Sundler F. The ghrelin cell: a novel developmentally regulated islet cell in the human pancreas. REGULATORY PEPTIDES 2002; 107:63-9. [PMID: 12137967 DOI: 10.1016/s0167-0115(02)00067-8] [Citation(s) in RCA: 271] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), was recently identified in the stomach. Ghrelin is produced in a population of endocrine cells in the gastric mucosa, but expression in intestine, hypothalamus and testis has also been reported. Recent data indicate that ghrelin affects insulin secretion and plays a direct role in metabolic regulation and energy balance. On the basis of these findings, we decided to examine whether ghrelin is expressed in human pancreas. Specimens from fetal to adult human pancreas and stomach were studied by immunocytochemistry, for ghrelin and islet hormones, and in situ hybridisation, for ghrelin mRNA. RESULTS We identified ghrelin expression in a separate population of islet cells in human fetal, neonatal, and adult pancreas. Pancreatic ghrelin cells were numerous from midgestation to early postnatally (10% of all endocrine cells). The cells were few, but regularly seen in adults as single cells at the islet periphery, in exocrine tissue, in ducts, and in pancreatic ganglia. Ghrelin cells did not express any of the known islet hormones. In fetuses, at midgestation, ghrelin cells in the pancreas clearly outnumbered those in the stomach. CONCLUSIONS Ghrelin is expressed in a quite prominent endocrine cell population in human fetal pancreas, and ghrelin expression in the pancreas precedes by far that in the stomach. Pancreatic ghrelin cells remain in adult islets at lower numbers. Ghrelin is not co-expressed with any known islet hormone, and the ghrelin cells may therefore constitute a new islet cell type.
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Affiliation(s)
- N Wierup
- Department of Physiological Sciences, Section of Neuroendocrine Cell Biology, Lund University, BMC F10, 22 184, Lund, Sweden.
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25
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Zaki M, Koduru S, McCuen R, Vuyyuru L, Schubert ML. Amylin, released from the gastric fundus, stimulates somatostatin and thus inhibits histamine and acid secretion in mice. Gastroenterology 2002; 123:247-55. [PMID: 12105853 DOI: 10.1053/gast.2002.34176] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND & AIMS Amylin, a peptide that displays 50% homology with calcitonin gene-related peptide (CGRP), is colocalized with somatostatin in endocrine cells of the gastric fundus. The present study was designed to determine the mechanism of action of amylin on gastric exocrine and endocrine secretion. METHODS Acid secretion was measured in the isolated mouse stomach by titration. Somatostatin and histamine secretion were measured in rat fundic segments by radioimmunoassay. RESULTS In isolated mouse stomach, amylin caused a concentration-dependent decrease in acid secretion. In rat fundic segments, amylin and CGRP each caused a concentration-dependent increase in somatostatin and a decrease in histamine secretion. Changes in histamine secretion induced by amylin reflected changes in somatostatin secretion and could be abolished by addition of somatostatin antibody. Both the somatostatin and the histamine responses to amylin were abolished by the selective amylin antagonist AC187 but were unaffected by the CGRP antagonist CGRP8-37. In contrast, the responses to CGRP were abolished by CGRP8-37 but were unaffected by AC187. AC187 alone decreased somatostatin and increased histamine in fundic segments and increased acid secretion in isolated stomach, indicating that endogenous amylin participates in the regulation of gastric endocrine (somatostatin and histamine) and exocrine (acid) secretion. CONCLUSIONS In gastric fundus, release of amylin from somatostatin cells interacts with distinct amylin receptors to enhance somatostatin secretion via an autocrine pathway that leads to inhibition of histamine and acid secretion.
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Affiliation(s)
- Muhammad Zaki
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, USA
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Abstract
Adrenomedullin (AM) is a multiregulatory peptide which is expressed in a wide range of tissues. In the pancreas, AM was first found in mammals, including man, and its colocalization with the pancreatic polypeptide (PP) was established in islet F cells. In addition, three different AM receptors have been characterized in B-cells. AM has been also located in the pancreatic cells of other vertebrate classes. The frequency and distribution of AM cells vary between different animals; they can be found scattered among the exocrine tissue, in the islets, or in ductal epithelia. The colocalization of AM with other hormones presents different patterns, although in birds, as in mammals, it seems to colocalize only with PP. The best-determined pancreatic AM function is the inhibition of insulin secretion in B-cells, which seems to be linked to a recently discovered binding protein, factor H. In relation to this physiological role, clinical data show that AM is raised in some groups of both types I and II diabetic patients and AM might have triggered the disease in a subset of them. On the other hand, AM pancreatic cells are also involved in the response to septic shock by increasing AM circulating levels. A third putative function is the inhibition of amylase secretion by the exocrine pancreatic cells. AM has been found in embryonic mammalian pancreas from the earliest stages of the development, colocalizing with all pancreatic hormones, although in adults only coexpression with PP is kept. AM may play a role in the growth and morphogenesis of the pancreas.
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Affiliation(s)
- José López
- Department of Biology, Cell Biology Unit, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain.
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27
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Cooper GJS. Amylin and Related Proteins: Physiology and Pathophysiology. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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D'Este L, Wimalawansa SJ, Renda TG. Distribution of amylin-immunoreactive neurons in the monkey hypothalamus and their relationships with the histaminergic system. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2001; 64:295-303. [PMID: 11575425 DOI: 10.1679/aohc.64.295] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Amylin (AMY) is a 37 amino acid peptide of pancreatic origin that has been localized in peripheral and central nervous structures. Both peripheral and central injection of the peptide causes various effects, including anorectic behavior in rats. Prompted by previous reports showing that the anorectic effect of AMY is mediated by histamine release, we immunohistochemically investigated possible relationships between these two systems at the light microscopical level. Monkey (Macaca fuscata japonica) hypothalamus specimens were submitted to immunohistochemical double staining procedures using AMY and histidine decarboxylase (HDC) antisera. AMY-immunoreactive neurons were found widely distributed in several nuclei of the monkey hypothalamus including the supraoptic, paraventricular, perifornical, periventricular, ventromedial, arcuate, and tuberomammillary nuclei. We detected AMY-immunoreactive nerve fibers throughout the hypothalamus, the median eminence and hypothalamus-neurohypophysial tract. Although AMY- and HDC-immunoreactive neuronal cell bodies occupied distinct hypothalamic zones, many HDC-immunoreactive cell bodies and dendrites, particularly those in the periventricular, arcuate, and rostral tuberomammillary regions, were surrounded by numerous AMY-immunoreactive nerve fiber varicosities. These findings demonstrate for the first time the presence of a discrete number of AMY-immunoreactive neurons in the monkey hypothalamus and add morphological support to the experimental data demonstrating that AMY probably exerts its influence on food intake via the histaminergic system.
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Affiliation(s)
- L D'Este
- Institute of Human Anatomy, University La Sapienza, Rome, Italy.
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29
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Abstract
Immunohistochemical studies were conducted on rat brainstem using a specific polyclonal antiserum against the COOH-terminal (25-37) of human amylin. Amylin-immunoreactive cell bodies were observed in the vestibular, cochlear, trapezoid, and inner cerebellar nuclei and in the mesencephalic nucleus of trigeminal nerve. Positive cell bodies were also found in lateral, gigantocellular and magnocellular reticular nuclei. Numerous amylin-immunoreactive nerve fibers were shown in the trigeminal spinal tract, in the solitary area and in the area postrema. Amylin-immunoreactive cell bodies were often surrounded by a network of tyrosine hydroxylase-immunoreactive nerve fibers. These results provide morphologic evidence that amylin may play a role in some discrete sensory functions.
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Affiliation(s)
- L D'Este
- Institute of Human Anatomy, University La Sapienza, Via Alfonso Borelli 50, I-00161, Rome, Italy.
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30
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Abstract
This review discusses the current concepts for the classification of gastric endocrine cells subdivided according to the type of mucosa in which they are located. In the oxyntic mucosa, the most important cell type is the ECL cell, involved in the synthesis and secretion of histamine. Proteins involved in many aspects of the biology of ECL cells including the response to the gastrin stimulus, membrane transport and docking, prevention of apoptosis, calcium homeostasis, autocrine activity, and maintenance of the differentiated cell phenotype have been localized to this cell type. Other cells of the oxyntic mucosa include: the D and EC cells producing somatostatin and serotonin, respectively, delivered through long cell processes; the X (or A-like) cells, possibly producing endothelin; and the D(1) and P cells of unknown function and possibly representing morphological variants of other cell types. In the antral mucosa, the three important cell types are represented by: the gastrin-producing G cells; the somatostatin-producing D cells, which are anatomically and functionally associated with G cells; and the serotonin-producing EC cells, which are located at the bottom of antral glands.
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Affiliation(s)
- C Bordi
- Istituto di Anatomia ed Istologia Patologica, Università di Parma, I-43100 Parma, Italy.
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31
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Martínez A, Kapas S, Miller MJ, Ward Y, Cuttitta F. Coexpression of receptors for adrenomedullin, calcitonin gene-related peptide, and amylin in pancreatic beta-cells. Endocrinology 2000; 141:406-11. [PMID: 10614663 DOI: 10.1210/endo.141.1.7261] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Three receptors have been characterized by their ability to bind adrenomedullin (AM): L1, RDC1, and CRLR. Immunohistochemical analysis and RT-PCR showed that all three receptors are expressed by the insulin-producing cells of the islets of Langerhans. RDC1 and CRLR in the presence of particular modifying proteins can also bind calcitonin gene-related peptide (CGRP). Such data suggest that the inhibitory effect caused by both AM and CGRP on insulin secretion is mediated by a direct interaction with the beta-cell. We also identified receptors for amylin, the third member of the AM peptide family, in mouse insulin-secreting cells. The beta-cells located closer to the periphery of the islets had a stronger immunoreactivity for the AM/ CGRP receptors. This observation could be related to a paracrine mechanism, given the proximity of AM- and CGRP-secreting cells (F and delta-cells, respectively), which are located at the periphery of the islets. Interestingly, the smooth muscle cells in the pancreatic vasculature expressed only RDC1, which is in agreement with physiological data showing that AM functions in the cardiovascular system are mainly mediated through a CGRP1 receptor. These data further implicate AM and the other components of its peptide family as important regulators of insulin release.
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Affiliation(s)
- A Martínez
- Department of Cell and Cancer Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Mulder H, Jongsma H, Zhang Y, Gebre-Medhin S, Sundler F, Danielsen N. Pituitary adenylate cyclase-activating polypeptide and islet amyloid polypeptide in primary sensory neurons: functional implications from plasticity in expression on nerve injury and inflammation. Mol Neurobiol 1999; 19:229-53. [PMID: 10495105 DOI: 10.1007/bf02821715] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Primary sensory neurons serve a dual role as afferent neurons, conveying sensory information from the periphery to the central nervous system, and as efferent effectors mediating, e.g., neurogenic inflammation. Neuropeptides are crucial for both these mechanisms in primary sensory neurons. In afferent functions, they act as messengers and modulators in addition to a principal transmitter; by release from peripheral terminals, they induce an efferent response, "neurogenic inflammation," which comprises vasodilatation, plasma extravasation, and recruitment of immune cells. In this article, we introduce two novel members of the sensory neuropeptide family: pituitary adenylate cyclase-activating polypeptide (PACAP) and islet amyloid polypeptide (IAPP). Whereas PACAP, a vasoactive intestinal polypeptide-resembling peptide, predominantly occurs in neuronal elements, IAPP, which is structurally related to calcitonin gene-related peptide, is most widely known as a pancreatic beta-cell peptide; as such, it has been recognized as a constituent of amyloid deposits in type 2 diabetes. In primary sensory neurons, under normal conditions, both peptides are predominantly expressed in small-sized nerve cell bodies, suggesting a role in nociception. On axotomy, the expression of PACAP is rapidly induced, whereas that of IAPP is reduced. Such a regulation of PACAP suggests that it serves a protective role during nerve injury, but that of IAPP may indicate that it is an excitatory messenger under normal conditions. In contrast, in localized adjuvant-induced inflammation, expression of both peptides is rapidly induced. For IAPP, studies in IAPP-deficient mice support the notion that IAPP is a pronociceptive peptide, because these mutant mice display a reduced nociceptive response when challenged with formalin.
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Affiliation(s)
- H Mulder
- Department of Cell and Molecular Biology, Lund University, Sweden.
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Wallace TJ, Ghosh S, McLean Grogan W. Molecular cloning and expression of rat lung carboxylesterase and its potential role in the detoxification of organophosphorus compounds. Am J Respir Cell Mol Biol 1999; 20:1201-8. [PMID: 10340939 DOI: 10.1165/ajrcmb.20.6.3402] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The 1,839-base pair complementary DNA (cDNA) for rat lung carboxylesterase was cloned by reverse transcriptase polymerase chain reaction from total rat lung RNA using specific primers derived from the 5' and 3' untranslated regions of rat hepatic cholesteryl ester hydrolase (CEH). The unique cDNA was sequenced and found to be similar to hepatic CEH, pI 6.1 esterase, and hydrolase A. In Northern blot analysis, the cDNA hybridized with a single band from lung messenger RNA (mRNA). The 1.7-kb coding sequence, predicting a 62-kD protein, was transfected into COS-7 cells and Chinese hamster ovary (CHO) cells. Expression in COS-7 and CHO cells was accompanied by 4- and 3.2-fold increases in carboxylesterase activity (hydrolysis of p-nitrophenyl acetate), respectively. Unlike the hepatic CEH, the expressed lung carboxylesterase described here did not hydrolyze cholesterol esters. In situ hybridization experiments localized the lung carboxylesterase mRNA to the airway epithelium. The organophosphorus compound phosphoric acid diethyl 4-nitrophenyl ester, paraoxon, completely inhibited this lung carboxylesterase, placing it in the family of B esterases by this criterion.
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Affiliation(s)
- T J Wallace
- Department of Biochemistry and Molecular Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298-0614, USA
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Karlsson S, Sundler F, Ahrén B. CCK receptor subtype in insulin-producing cells: a combined functional and in situ hybridization study in rat islets and a rat insulinoma cell line. REGULATORY PEPTIDES 1998; 78:95-103. [PMID: 9879752 DOI: 10.1016/s0167-0115(98)00136-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cholecystokinin (CCK) stimulates insulin secretion. It is, however, not established whether CCK receptors are expressed in insulin-producing cells. We therefore investigated, by in situ hybridization, whether CCK-A or CCK-B receptor mRNA could be detected in normal rat pancreatic islets and in the rat insulinoma cell line, RINm5F. The CCK-A, but not the CCK-B, receptor transcript was detected in both islets and RINm5F cells. Islet CCK-A receptors were mostly confined to the center of the islets corresponding to the distribution of the B cells. In RINm5F cells, insulin release was not significantly affected by cholecystokinin (CCK)-8-S (10(-13) to 10(-7) M), which is in contrast to the insulinotropic effect of CCK-8-S in normal rat islets. Similarly, in FURA-2AM-loaded cells, CCK-8-S (10(-11) to 10(-7) M) was without effect on the intracellular Ca2+ concentration ([Ca2+]ic) in RINm5F cells, whereas CCK-8-S (10(-7) M) markedly increased [Ca2+]ic (by 366+/-2 nM (P < 0.001) in normal rat islet cells. We conclude that the CCK-A, but not the CCK-B, receptor subtype is expressed in both normal rat islets and in the rat insulinoma-derived cell line RINmS5F. There is, however, a functional difference between normal islets and the RINm5F cells with respect to effects of CCK-8-S on insulin release and [Ca2+]ic.
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Affiliation(s)
- S Karlsson
- Department of Medicine, Malmö, The Wallenberg Laboratory, Malmö University Hospital, Sweden.
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Mulder H, Myrsén-Axcrona U, Gebre-Medhin S, Ekblad E, Sundler F. Expression of non-classical islet hormone-like peptides during the embryonic development of the pancreas. Microsc Res Tech 1998; 43:313-21. [PMID: 9849972 DOI: 10.1002/(sici)1097-0029(19981115)43:4<313::aid-jemt5>3.0.co;2-c] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding of islet embryogenesis may prove to be key in the design of future therapies for diabetes directed at re-initiating islet growth, with the goal to replace and/or replenish the impaired beta-cell mass in the disease. In this context, studies of islet neurohormonal peptides, known to play a role in the local regulation of islet function, and their expression during islet embryogenesis are important. Here we review our studies on the embryonic islet expression of islet amyloid polypeptide (IAPP) and the PP-fold peptides pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY). IAPP, which is constitutively expressed in beta- and delta-cells in the adult rat, was found to occur in the assumed pluripotent islet progenitor cell, together with PYY, glucagon, and to a lesser extent with insulin. As development proceeds, the insulin/IAPP phenotype is segregated from that of PYY/glucagon; with the formation of islet-like structures, insulin/IAPP-expressing cells primarily occupy their central portions, while PYY/glucagon-expressing cells are found in their periphery. At the time of formation of islet-like structures, expression of NPY is induced in the insulin/IAPP-containing cells. Whereas NPY-expression ceases at birth, PYY is constitutively expressed in non-beta-cells in the mature rat. Expression of PP is induced just prior to birth in a separate population of islet cells, occasionally co-expressed with PYY. Although a clear role for these peptides during embryogenesis has not been identified, they conceivably could play a role in the control of insulin secretion, islet growth and islet blood flow.
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Affiliation(s)
- H Mulder
- Department of Physiology and Neuroscience, Lund University, Sweden.
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Abstract
BACKGROUND Autotransplantation of parathyroid glands in man is performed to preserve parathyroid function after surgery. In a rat model, we performed autotransplantation into the renal subcapsular space to examine reinnervation and changes in cell activity in the transplanted glands. METHODS Parathyroids grafted for 1-20 weeks were examined immunocytochemically for general and specific neuroendocrine markers to visualize nerve fibers and glandular cells and for bromodeoxyuridine to determine cell proliferation. In situ hybridization was used to localize and quantitate chromogranin A and parathyroid hormone (PTH) mRNA expression. RESULTS Reinnervation was observed as early as 1 week after transplantation in that nerve fibers containing the general neuronal marker protein gene product 9.5 appeared along blood vessels. During the following 20 weeks, the nerve fiber density increased gradually. One week after transplantation, the immunoreaction intensity for PTH, chromogranin A, and pancreastatin was lower than in control glands. Bromodeoxyuridine-labeled cells were fewer than in control glands at 1 week and at 5-10 weeks after transplantation. The density of PTH mRNA labeling was lower than in control glands during the whole time period studied and reached a minimum after 10 weeks. The density of chromogranin A mRNA labeling was unaffected at 1 and 3 weeks after transplantation and then decreased to a minimum at 10 weeks after transplantation; at 20 weeks, the chromogranin A mRNA labeling had again reached the level in control glands. CONCLUSION The changes in PTH and chromogranin A immunoreaction intensity and mRNA density indicate reduced hormone production for several weeks after transplantation. Our results using transmitter-specific markers indicate a rapid ingrowth of mostly sympathetic nerve fibers, preferentially around blood vessels. Later on, parasympathetic and sensory nerve fibers reached the grafts. The parathyroid innervation may be of importance for parathyroid hormone regulation, and the finding of an early reinnervation could be of clinical importance.
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Affiliation(s)
- L Luts
- Department of Physiology and Neuroscience, University of Lund, Sweden
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Filipsson K, Sundler F, Hannibal J, Ahrén B. PACAP and PACAP receptors in insulin producing tissues: localization and effects. REGULATORY PEPTIDES 1998; 74:167-75. [PMID: 9712178 DOI: 10.1016/s0167-0115(98)00037-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have studied the localization, receptor occupancy and potency of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) in insulin-producing tissues. Immunocytochemistry showed that PACAP-like immunoreactivity (PACAP-IR) was localized to pancreatic nerves with accumulation in intrapancreatic ganglia in both mouse and rat. In contrast, PACAP-IR could not be demonstrated in endocrine cells. Furthermore, in situ hybridization, using oligodeoxyribonucleotide probes recognizing mRNA for PACAP receptors, demonstrated that mouse and rat pancreas, and the insulinoma cell lines HIT-T15 and RINm5F, expressed both the PACAP type 1 and the VIP2/PACAP receptors. Moreover, both PACAP27 and PACAP38 dose-dependently (0.1 nM to 100 nM) and equipotently stimulated insulin secretion in isolated mouse and rat islets and in HIT-T15 and RINm5F cells. Furthermore, in mouse islets, vasoactive intestinal polypeptide (VIP) was of equal potency as PACAP at stimulating insulin secretion. In mouse, PACAP also stimulated insulin secretion in a subfraction of the isolated islets also at the low dose of 1 fM. Thus, (1) PACAP is exclusively a neuropeptide in the pancreas, (2) insulin-producing cells express PACAP type 1 and VIP2/PACAP receptors and (3) the two forms of PACAP equipotently stimulate insulin secretion. Based on these results, we suggest that PACAP is involved in the neural regulation of insulin secretion.
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Affiliation(s)
- K Filipsson
- Department of Medicine, Malmö University Hospital, Sweden.
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38
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van Rossum D, Hanisch UK, Quirion R. Neuroanatomical localization, pharmacological characterization and functions of CGRP, related peptides and their receptors. Neurosci Biobehav Rev 1997; 21:649-78. [PMID: 9353797 DOI: 10.1016/s0149-7634(96)00023-1] [Citation(s) in RCA: 381] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Calcitonin generelated peptide (CGRP) is a neuropeptide discovered by a molecular approach over 10 years ago. More recently, islet amyloid polypeptide or amylin, and adrenomedullin were isolated from human insulinoma and pheochromocytoma respectively, and revealed between 25 and 50% sequence homology with CGRP. This review discusses findings on the anatomical distributions of CGRP mRNA, CGRP-like immunoreactivity and receptors in the central nervous system, as well as the potential physiological roles for CGRP. The anatomical distribution and biological activities of amylin and adrenomedullin are also presented. Based upon the differential biological activity of various CGRP analogs, the CGRP receptors have been classified in two major classes, namely the CGRP1 and CGRP2 subtypes. A third subtype has also been proposed (e.g. in the nucleus accumbens) as it does not share the pharmacological properties of the other two classes. The anatomical distribution and the pharmacological characteristics of amylin binding sites in the rat brain are different from those reported for CGRP but share several similarities with the salmon calcitonin receptors. The receptors identified thus far for CGRP and related peptides belong to the G protein-coupled receptor superfamily. Indeed, modulation of adenylate cyclase activity following receptor activation has been reported for CGRP, amylin and adrenomedullin. Furthermore, the binding affinity of CGRP and related peptides is modulated by nucleotides such as GTP. The cloning of various calcitonin and most recently of CGRP1 and adrenomedullin receptors was reported and revealed structural similarities but also significant differences to other members of the G protein-coupled receptors. They may thus form a new subfamily. The cloning of the amylin receptor(s) as well as of the other putative CGRP receptor subtype(s) are still awaited. Finally, a broad variety of biological activities has been described for CGRP-like peptides. These include vasodilation, nociception, glucose uptake and the stimulation of glycolysis in skeletal muscles. These effects may thus suggest their potential role and therapeutic applications in migraine, subarachnoid haemorrhage, diabetes and pain-related mechanisms, among other disorders.
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Affiliation(s)
- D van Rossum
- Department of Pharmacology, McGill University, Douglas Hospital Research Centre, Verdun, Québec, Canada
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Carty MD, Lillquist JS, Peshavaria M, Stein R, Soeller WC. Identification of cis- and trans-active factors regulating human islet amyloid polypeptide gene expression in pancreatic beta-cells. J Biol Chem 1997; 272:11986-93. [PMID: 9115263 DOI: 10.1074/jbc.272.18.11986] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Islet amyloid polypeptide is expressed almost exclusively in pancreatic beta- and delta-cells. Here we report that beta cell-specific expression of the human islet amyloid polypeptide gene is principally regulated by promoter proximal sequences. The sequences that control tissue-specific expression were mapped between nucleotides -2798 and +450 of the human islet amyloid polypeptide (IAPP) gene using transgenic mice. To localize the cis-acting elements involved in this response, we examined the effects of mutations within these sequences using transfected islet amyloid polypeptide promoter expression constructs in pancreatic beta cell lines. The sequences between -222 and +450 bp were found to be necessary for beta cell-specific expression. Linker-scanning mutations of the 5'-promoter proximal region defined several key distinct control elements, including a negative-acting element at -111/-102 base pairs (bp), positive-acting elements like the basic helix-loop-helix-like binding site at -138/-131 bp, and the three A/T-rich, homeobox-like sites at -172/-163, -154/-142, and -91/-84 bp. Mutations within any one of these elements eliminated transcriptional expression by the promoter. Gel mobility shift assays revealed that the PDX-1 homeobox factor, which is required for insulin gene transcription in beta cells, interacted specifically at the -154/-142- and -91/-84-bp sites. Since PDX-1 is highly enriched in beta and delta cells, these results suggest that this factor plays a principal role in defining islet beta cell- and delta cell-specific expression of the IAPP gene.
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Affiliation(s)
- M D Carty
- Department of Molecular Sciences, Central Research Division, Pfizer, Inc., Groton, Connecticut 06340, USA
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40
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Myrsén-Axcrona U, Ekblad E, Sundler F. Developmental expression of NPY, PYY and PP in the rat pancreas and their coexistence with islet hormones. REGULATORY PEPTIDES 1997; 68:165-75. [PMID: 9100283 DOI: 10.1016/s0167-0115(96)02113-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It has been suggested that members of the neuropeptide Y (NPY) family of regulatory peptides [NPY, peptide YY (PYY) and pancreatic polypeptide (PP)] play an important role in the development of the endocrine pancreas. The development of rat endocrine pancreas from embryonic (E) day 12 until 30 days postpartum (P) was studied with emphasis on NPY, PYY and PP and their co-existence with insulin, glucagon and somatostatin using single and double immunostaining and in situ hybridization. Already at E12, PYY was detectable in small endocrine cell clusters and found to be co-localised with both insulin and glucagon, which at this stage occurred in the same cells. At E16 most of the insulin-immunoreactive (IR) cells were distinct from the glucagon/PYY-IR cells. Interestingly, at E16 NPY mRNA, and at E17 NPY immunoreactivity appeared in a few, scattered endocrine cells. Virtually all NPY-IR endocrine cells were insulin-producing beta cells. At E18 the endocrine cells started to form typical islets with centrally located insulin/NPY-IR cells surrounded by glucagon/PYY-IR cells. AT E20-E21, the vast majority of insulin-producing cells also expressed NPY. However, at birth (day 0) islet cell NPY mRNA was lacking. Postnatally the number and immunostaining intensity of NPY-IR islet cells rapidly declined, being non-detectable at P5. Cells containing PP immunoreactivity and PP mRNA were first detected at E21. The adult pattern of islet peptide distribution, with NPY confined to neuronal elements. PYY and PP exclusively in endocrine cells, was established at P5. The beta cell expression of NPY during the latter part of embryogenesis coincides with the prepartal glucocorticoid surge and with rapid islet cell replication and differentiation. This is compatible with steroid induction of NPY expression and with a role for NPY in the maturation of beta cells and their hormone release, which occurs in the immediate neonatal period.
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Affiliation(s)
- U Myrsén-Axcrona
- Department of Physiology and Neuroscience, Lund University Hospital, University of Lund, Sweden
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41
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Mulder H, Ekelund M, Ekblad E, Sundler F. Islet amyloid polypeptide in the gut and pancreas: localization, ontogeny and gut motility effects. Peptides 1997; 18:771-83. [PMID: 9285924 DOI: 10.1016/s0196-9781(97)00008-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The occurrence of islet amyloid polypeptide (IAPP) in the gut and pancreas of several species and during ontogeny of the rat, was studied using immunocytochemistry. Effects of IAPP on rat ileal smooth muscle were assessed in vitro. Islets of most, but not all, species examined, displayed IAPP in insulin cells and, in some species, also in somatostatin- and peptide YY (PYY)-containing cells. In the gut, expression of IAPP varied among species; when present, IAPP was most abundant in the proximal part and co-localized with somatostatin, PYY, gastrin/cholecystokinin, enteroglucagon or serotonin. IAPP was first demonstrated at embryonic day 12 and 16 in islet and gastrointestinal endocrine cells, respectively. IAPP relaxed gut muscle and reduced electrical field stimulation-evoked contractions, presumably by inhibiting acetylcholine release. Thus, IAPP expression in islets is consistent with an important role for IAPP in fuel metabolism; the gastrointestinal expression and motor effects of IAPP suggest that IAPP may modulate gastrointestinal function.
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Affiliation(s)
- H Mulder
- Department of Physiology and Neuroscience, University of Lund, Lund University Hospital, Sweden.
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Ahrén B, Simonsson E, Scheurink AJ, Mulder H, Myrsén U, Sundler F. Dissociated insulinotropic sensitivity to glucose and carbachol in high-fat diet-induced insulin resistance in C57BL/6J mice. Metabolism 1997; 46:97-106. [PMID: 9005977 DOI: 10.1016/s0026-0495(97)90175-x] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To study islet function following reduced insulin sensitivity, we examined mice of the C57BL/6J strain, the genotype of which carries an increased propensity to develop insulin resistance when metabolically challenged. The mice received either a high-fat diet (58% fat on an energy basis) or a control diet (11% fat) for 12 weeks. The body weight of mice on the high-fat diet increased significantly more than that of mice on the control diet (25.8 +/- 0.4 v 21.3 +/- 0.2 g, P < .001). Already after 1 week on the high-fat diet, a significant hyperglycemia accompanied by hyperinsulinemia had evolved, indicative of insulin resistance. After 12 weeks, plasma glucose levels for high-fat diet-treated mice were 7.5 +/- 0.1 mmol/L, versus 6.5 +/- 0.1 mmol/L in controls (P < .001); corresponding values for plasma insulin were 248 +/- 17 and 104 +/- 7 pmol/L, respectively (P < .001). Mice given a high-fat diet also had elevated levels of total cholesterol, triglycerides, and free fatty acids (FFAs) compared with controls. After 4, 8, and 12 weeks, glucose (2.8, 8.3, or 16.7 mmol/kg) or the cholinergic agonist carbachol (0.16 or 0.53 micromol/kg) was injected intraperitoneally. The insulinotropic response to glucose was not different between the two groups after 4 or 8 weeks, whereas after 12 weeks, glucose-induced insulin secretion was markedly impaired in high-fat diet-treated mice (P < .001). In contrast, after 8 and 12 weeks on a high-fat diet, carbachol-stimulated insulin secretion was potentiated (P < .01), whereas carbachol-stimulated glucagon secretion was not significantly altered. Furthermore, after 12 weeks on the high-fat diet, insulin secretion from isolated islets was impaired at glucose levels of 8.3, 11.1, and 16.7 mmol/L (P < or = .05). Moreover, islet morphology as examined by immunocytochemistry using insulin antibodies and islet innervation, as revealed by immunostaining of tyrosine hydroxylase (TH), neuropeptide Y (NPY), galanin, vasoactive intestinal polypeptide (VIP), and substance P (SP) were unaffected by the high-fat diet for 12 weeks. However, quantitative in situ hybridization showed a 3.5-fold upregulation of insulin gene expression in response to the high-fat diet (P < .001) despite unaltered B-cell mass and pancreatic insulin content. We conclude that as little as 1 week of treatment with a high-fat diet induces insulin resistance in C57BL/6J mice. This is accompanied later by hyperlipemia, potentiated carbachol-stimulated insulin secretion, and increased insulin gene expression but impaired glucose-stimulated insulin secretion. We suggest that after several weeks' duration, insulin resistance is accompanied by enhanced islet sensitivity to cholinergic activation and exaggerated insulin gene expression, whereas the failing islet sensitivity to glucose represents decompensation.
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Affiliation(s)
- B Ahrén
- Department of Medicine, Lund University, Malmö, Sweden
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43
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Mulder H, Ahrén B, Sundler F. Islet amyloid polypeptide and insulin gene expression are regulated in parallel by glucose in vivo in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:E1008-14. [PMID: 8997219 DOI: 10.1152/ajpendo.1996.271.6.e1008] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Islet amyloid polypeptide (IAPP) is a novel amyloid-forming beta-cell hormone with putative roles in glucose metabolism and non-insulin-dependent diabetes mellitus (NIDDM) pathogenesis. To study how IAPP and insulin expression are regulated by glucose, rats were fasted for 48h followed by administration of glucose at repeated 4-h intervals; IAPP and insulin mRNA levels were determined by quantitative in situ hybridization. Fasting markedly reduced IAPP and insulin mRNA levels. Two (6 h) and four (14 h) glucose injections dose dependently increased both mRNA levels; the effects were matched by similar changes in plasma glucose levels. Actinomycin D blocked the glucose-induced increase in IAPP expression. IAPP and insulin mRNA levels were significantly correlated over the range of glucose levels. The parallel regulation of IAPP and insulin gene expression by glucose is consistent with a role for IAPP in glucose homeostasis. Thus, under hyperglycemic conditions such as NIDDM, IAPP gene expression is likely to increase. Hence, IAPP could, by elevated local concentrations, contribute to amyloid formation and/or affect metabolism unfavorably by inhibition of insulin release and action.
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Affiliation(s)
- H Mulder
- Department of Physiology and Neuroscience, University of Lund, Sweden
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Sörhede M, Mulder H, Mei J, Sundler F, Erlanson-Albertsson C. Procolipase is produced in the rat stomach--a novel source of enterostatin. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1301:207-12. [PMID: 8664330 DOI: 10.1016/0005-2760(96)00034-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Procolipase was identified in the stomach by in situ hybridisation. A strong autoradiographic labelling of chief cells was seen in the fundus region, declining more distally and being almost absent in antrum. There was no labelling seen in the intestine. Colipase activity was estimated in rat gastric juice following pentagastrin stimulation and was found to average 2 microM. Furthermore, enterostatin, the N-terminal pentapeptide of procolipase, has been identified in the rat gut and pancreas. Extracts from gastric mucosa, intestinal mucosa and pancreas were purified by gel filtration (Sephadex G25), ion-exchange chromatography (CM-Sepharose) and HPLC (C18 reverse phase). Using an ELISA assay with antibodies directed against enterostatin, two forms of the peptide were identified both in the gut and in the pancreas, with the amino-acid sequences APGPR and VPGPR, respectively. APGPR was found to be the predominant form of enterostatin, whereas only a small amount had the structure VPGPR. Enterostatin in the form of APGPR, when injected intracerebroventricularly in female Sprague-Dawley rats, significantly reduced high-fat food intake in a two-choice situation of low-fat (14% fat by energy) and high-fat (38% fat) food. It is concluded that procolipase is produced in the stomach and secreted into the gastric juice. This is also a novel source of enterostatin.
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Affiliation(s)
- M Sörhede
- Department of Cell and Molecular Biology, University of Lund, Sweden.
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45
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Mulder H, Ahrén B, Sundler F. Islet amyloid polypeptide (amylin) and insulin are differentially expressed in chronic diabetes induced by streptozotocin in rats. Diabetologia 1996; 39:649-57. [PMID: 8781760 DOI: 10.1007/bf00418536] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Islet amyloid polypeptide (IAPP) is overexpressed relative to insulin under several experimental conditions relevant to diabetes mellitus, including the immediate phase (7 days) following induction of streptozotocin diabetes. In the present study, IAPP and insulin gene expression were examined in chronic streptozotocin diabetes (3 weeks) in rats. Quantitative in situ hybridization, determining grain areas and optical densities of mRNA labelling, revealed that IAPP and insulin expression were reduced at the islet level at both low and high streptozotocin doses, partly due to reduced beta-cell mass. In contrast, the cellular levels of IAPP mRNA were either increased or unaffected at the low and high streptozotocin doses, respectively, whereas those of insulin mRNA were unaffected or reduced. When dexamethasone was administered to rats given the low streptozotocin dose, IAPP expression was increased, whereas that of insulin was markedly reduced. Immunocytochemistry revealed that IAPP predominantly occurred in insulin cells and to a lesser extent in somatostatin cells at all treatments examined. Our findings demonstrate that IAPP and insulin gene expression are differentially regulated; the over-expression of IAPP relative to insulin is augmented when the beta-cell insult is aggravated, in our experiments represented by massive beta-cell destruction (high streptozotocin dose) or a combination of moderate beta-cell damage and peripheral insulin resistance (low streptozotocin dose and dexamethasone). An over-expression of IAPP relative to insulin may therefore be involved in diabetes pathogenesis, contributing to its metabolic perturbations, possibly through the capacity of IAPP to restrain insulin release and action and to form islet amyloid.
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Affiliation(s)
- H Mulder
- Department of Physiology and Neuroscience, University of Lund, Sweden
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46
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Mulder H, Ahrén B, Karlsson S, Sundler F. Adrenomedullin: localization in the gastrointestinal tract and effects on insulin secretion. REGULATORY PEPTIDES 1996; 62:107-12. [PMID: 8795072 DOI: 10.1016/0167-0115(96)00005-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Adrenomedullin is a novel hypotensive adrenal polypeptide originally isolated from a human pheochromocytoma and is structurally related to calcitonin gene-related peptide and islet amyloid polypeptide. Using immunocytochemistry, the occurrence of adrenomedullin in the adrenal gland and gastro-entero-pancreatic region in the rat was examined and its effect on insulin secretion from isolated rat islets was determined. Adrenomedullin-like immunoreactivity occurred in noradrenaline- and adrenaline-producing cells in the adrenal gland. Gastrointestinal endocrine cells, with increased density distally, displayed adrenomedullin-like immunoreactivity; these cells constituted a subpopulation of the enterochromaffin (serotonin-containing) cells. Co-localization of adrenomedullin with somatostatin, glicentin, gastrin/cholecystokinin, peptide YY or islet amyloid polypeptide was not encountered. Adrenomedullin-immunoreactive cells were not observed in the pancreatic islets. At 1, 10 and 100 nmol/l, adrenomedullin stimulated insulin release from isolated rat islets in the presence of 3.3 mmol/l glucose (P < 0.05) and at 100 nmol/l, the peptide potentiated insulin secretion also in the presence of 8.3 mmol/l glucose (P < 0.05). These findings suggest that, besides being an adrenal hypotensive peptide, adrenomedullin may be a gut hormone with a potential insulinotropic function.
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Affiliation(s)
- H Mulder
- Department of Physiology and Neuroscience, University of Lund, Sweden.
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Ahrén B, Sundkvist G, Mulder H, Sundler F. Blockade of muscarinic transmission increases the frequency of diabetes after low-dose alloxan challenge in the mouse. Diabetologia 1996; 39:383-90. [PMID: 8777987 DOI: 10.1007/bf00400669] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The diabetogenic action of the beta-cell toxin, alloxan, is transient when administered to mice at a dosage of 50 mg/kg. We examined whether increased cholinergic activity is involved in the compensatory mechanisms. Therefore, following administration of alloxan, methylatropine (32 mumol/kg) was given intraperitoneally once daily for 5 consecutive days. Methyl atropine worsened the degree of hyperglycaemia during the first week after alloxan administration. Recovery from the diabetes mellitus was observed in a substantial number of animals given alloxan without methyl atropine, whereas the risk of developing manifest diabetes was markedly enhanced by methyl atropine. At 35 days after alloxan administration, 33% of the animals, which were given alloxan alone and were diabetic after 4 days, still had diabetes. In contrast, of the animals rendered diabetic by alloxan with concomitant atropinization, 92% remained diabetic throughout the study (p = 0.0145 vs alloxan alone). Glucose-stimulated insulin secretion and pancreatic insulin content were markedly reduced in animals with diabetes while being less reduced in alloxan-injected animals without diabetes. Moreover, in situ hybridization and immunocytochemistry revealed markedly decreased levels of insulin mRNA and number of insulin cells in alloxan-treated animals. With regard to insulin secretion, pancreatic insulin content, insulin mRNA and insulin cell number, the reduction was the same irrespective of whether methyl atropine had been given. Thus, 5 days of atropinization increases the incidence of diabetes following alloxan at 50 mg/kg in mice. We suggest that cholinergic activity protects insulin cells from glucotoxicity during the first week after alloxan administration and therefore, reduces the frequency of diabetes.
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Affiliation(s)
- B Ahrén
- Department of Medicine, Malmö University Hospital, Sweden
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Myrsén U, Ahrén B, Sundler F. Neuropeptide Y is expressed in subpopulations of insulin- and non-insulin-producing islet cells in the rat after dexamethasone treatment: a combined immunocytochemical and in situ hybridisation study. REGULATORY PEPTIDES 1995; 60:19-31. [PMID: 8747781 DOI: 10.1016/0167-0115(95)00114-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Neuropeptide Y (NPY) is known to occur in adrenergic and non-adrenergic nerves in rat pancreatic islets. Analysis of islet extracts has revealed local NPY synthesis after glucocorticoid treatment. The cellular localisation of NPY expression in rat islets following dexamethasone treatment (2 mg/kg daily, for 12 days), was investigated by a combination of immunocytochemistry (ICC) and in situ hybridisation (ISH). NPY-immunoreactive nerve fibres were seen in pancreatic islets of both control and dexamethasone-treated rats. In the controls weak NPY immunoreactivity but no NPY mRNA was observed in occasional islets. After dexamethasone treatment, clusters of islet cells distributed both centrally and peripherally displayed intense NPY immunoreactivity and NPY mRNA labelling. Immunocytochemical double staining and ISH combined with ICC for NPY and islet hormones revealed that most NPY expressing cells were identical with insulin cells; a few cells were identical with somatostatin or pancreatic polypeptide (PP) cells. In contrast, glucagon cells seemed to be devoid of NPY immunoreactivity and NPY mRNA labelling. Thus, in the rat, glucocorticoids cause a marked upregulation of NPY expression in islet cells, preferentially the insulin cells. The expression of NPY might represent an islet adaptation mechanism to the reduced peripheral insulin sensitivity.
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Affiliation(s)
- U Myrsén
- Department of Medical Cell Research, University of Lund, Sweden
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Shen Z, Heinegård D, Sommarin Y. Distribution and expression of cartilage oligomeric matrix protein and bone sialoprotein show marked changes during rat femoral head development. Matrix Biol 1995; 14:773-81. [PMID: 8785592 DOI: 10.1016/s0945-053x(05)80020-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Distribution and sites of synthesis of a cartilage extracellular matrix protein, cartilage oligomeric matrix protein (COMP), and of a bone extracellular matrix protein, bone sialoprotein (BSP), were studied in the femoral head of growing Wistar rats from day 14 to day 60 by immunocytochemistry and in situ hybridization. This period includes formation of the secondary ossification center and differentiation of articular cartilage. At early stages, immunoreactivity for COMP was pronounced throughout the cartilage. The localization of COMP was predominantly territorial in the center of the immature femoral head and in the growth plate at all ages studied. In the superficial parts, a shift from a uniform extracellular matrix staining at day 14 to an interterritorial localization at day 33 to day 60 was seen, apparently concurrent with formation of articular cartilage. COMP staining, representing cartilage remnants, also extended into the center of the trabecular bone in the primary spongiosa. In the secondary ossification center, the staining for COMP decreased at the onset of calcification. The protein was only synthesized by chondrocytes, as shown by in situ hybridization. The highest level of COMP mRNA was detected in chondrocytes in the central region of the growth plate. In the layer corresponding to the articular cartilage of the femoral head, mRNA levels for COMP were low from day 14 to day 33 but were increased on day 60. This shows substantial synthesis in the developing articular cartilage. Immunoreactivity for BSP was detected in bone trabeculae of primary spongiosa. In situ hybridization showed the highest levels of BSP mRNA in regions of newly formed bone. BSP mRNA was detected in hypertrophic chondrocytes in the secondary ossification center as early as day 18, well before the appearance of immunochemically detectable BSP. Interestingly, simultaneous expression of COMP and BSP mRNA was seen after day 18 in hypertrophic chondrocytes of the growth plate and later also in hypertrophic chondrocytes close to the mineralization zone of the articular cartilage.
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Affiliation(s)
- Z Shen
- Department of Cell and Molecular Biology, University of Lund, Sweden
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Myrsén U, Sundler F. Neuropeptide Y is expressed in islet somatostatin cells of the hamster pancreas: a combined immunocytochemical and in situ hybridization study. REGULATORY PEPTIDES 1995; 57:65-76. [PMID: 7644704 DOI: 10.1016/0167-0115(95)00020-c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neuropeptide Y (NPY) is known to occur in the autonomic nervous system, including the pancreatic islet innervation. We now present evidence that NPY is also expressed in endocrine islet cells in hamster pancreas. Thus, NPY-immunoreactivity and gene expression were detected in peripheral islet cells, using immunocytochemistry (ICC), in situ hybridization (ISH), and a combination of these techniques. Double immunostaining for NPY and somatostatin enabled localisation of NPY ot the vast majority of the somatostatin cells. However, a few somatostatin cells were devoid of NPY immunoreactivity and an occasional NPY-immunoreactive cell was devoid of somatostatin. ISH with an NPY mRNA specific probe, showed labelling of cells in the islet periphery. Furthermore, combined ISH for NPY mRNA and ICC for somatostatin showed autoradiographic labelling of somatostatin cells to a varying degree. Both somatostatin and NPY are inhibitors of insulin and/or glucagon secretion. Thus, in the islets these two peptides may be coreleased and cooperate in the regulation of islet hormone secretion. The role for NPY emanating from islet cells is probably paracrine rather than endocrine.
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Affiliation(s)
- U Myrsén
- Department of Medical Cell Research, University of Lund, Sweden
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