Prolonged exposure to homocysteine results in diminished but reversible pancreatic beta-cell responsiveness to insulinotropic agents

Steven Patterson, Siobhan M. J. Scullion, Janie McCluskey, Peter Flatt, Neville McClenaghan

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background Plasma homocysteine levels may be elevated in poorly controlled diabetes with pre-existing vascular complications and/or nephropathy. Since homocysteine has detrimental effects on a wide diversity of cell types, the present study examined the effects of long-term homocysteine exposure on the secretory function of clonal BRIN-BD11 beta-cells. Methods Acute insulin secretory function, cellular insulin content and viability of BRIN-BD11 cells were assessed following long-term (18 h) exposure to homocysteine in culture. RT-PCR and Western blot analysis were used to determine the expression of key P-cell genes and proteins. Cells were cultured for a further 18 h without homocysteine to determine any long-lasting effects. Results Homocysteine (250-1000 mu mol/L) exposure reduced insulin secretion at both moderate (5.6 mmol/L) and stimulatory (16.7 mmol/L) glucose by 48-63%. Similarly, insulin secretory responsiveness to stimulatory concentrations of alanine, arginine, 2-ketoisocaproate, tolbutamide, KCI, elevated Ca2+, forskolin and PMA, GLP-1, GIP and CCK-8 were reduced by 11-62% following culture with 100-250 mu mol/L homocysteine. These inhibitory effects could not simply be attributed to changes in cellular insulin content, cell viability, H2O2 generation or any obvious alterations of gene/protein expression for insulin, glucokinase, GLUT2, VDCC, or Kir6.2 and SUR1. Additional culture for 18 h in standard culture media after homocysteine exposure restored secretory responsiveness to all agents tested. Conclusion These findings suggest that long-term exposure to high homocysteine levels causes a reversible impairment of pancreatic beta-cell insulinotropic pathways. The in vivo actions of hyperhomocysteinaemia on islet cell function merit investigation. Copyright (C) 2006 John Wiley & Sons, Ltd.
LanguageEnglish
Pages324-334
JournalDIABETES-METABOLISM RESEARCH AND REVIEWS
Volume23
Issue number4
DOIs
Publication statusPublished - May 2007

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Insulin-Secreting Cells
Homocysteine
Insulin
Glucokinase
Sincalide
Tolbutamide
Hyperhomocysteinemia
Glucagon-Like Peptide 1
Colforsin
Calcium Channels
Islets of Langerhans
Alanine
Blood Vessels
Culture Media
Cultured Cells
Cell Survival
Proteins
Western Blotting
Gene Expression
Glucose

Cite this

Patterson, Steven ; Scullion, Siobhan M. J. ; McCluskey, Janie ; Flatt, Peter ; McClenaghan, Neville. / Prolonged exposure to homocysteine results in diminished but reversible pancreatic beta-cell responsiveness to insulinotropic agents. In: DIABETES-METABOLISM RESEARCH AND REVIEWS. 2007 ; Vol. 23, No. 4. pp. 324-334.
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title = "Prolonged exposure to homocysteine results in diminished but reversible pancreatic beta-cell responsiveness to insulinotropic agents",
abstract = "Background Plasma homocysteine levels may be elevated in poorly controlled diabetes with pre-existing vascular complications and/or nephropathy. Since homocysteine has detrimental effects on a wide diversity of cell types, the present study examined the effects of long-term homocysteine exposure on the secretory function of clonal BRIN-BD11 beta-cells. Methods Acute insulin secretory function, cellular insulin content and viability of BRIN-BD11 cells were assessed following long-term (18 h) exposure to homocysteine in culture. RT-PCR and Western blot analysis were used to determine the expression of key P-cell genes and proteins. Cells were cultured for a further 18 h without homocysteine to determine any long-lasting effects. Results Homocysteine (250-1000 mu mol/L) exposure reduced insulin secretion at both moderate (5.6 mmol/L) and stimulatory (16.7 mmol/L) glucose by 48-63{\%}. Similarly, insulin secretory responsiveness to stimulatory concentrations of alanine, arginine, 2-ketoisocaproate, tolbutamide, KCI, elevated Ca2+, forskolin and PMA, GLP-1, GIP and CCK-8 were reduced by 11-62{\%} following culture with 100-250 mu mol/L homocysteine. These inhibitory effects could not simply be attributed to changes in cellular insulin content, cell viability, H2O2 generation or any obvious alterations of gene/protein expression for insulin, glucokinase, GLUT2, VDCC, or Kir6.2 and SUR1. Additional culture for 18 h in standard culture media after homocysteine exposure restored secretory responsiveness to all agents tested. Conclusion These findings suggest that long-term exposure to high homocysteine levels causes a reversible impairment of pancreatic beta-cell insulinotropic pathways. The in vivo actions of hyperhomocysteinaemia on islet cell function merit investigation. Copyright (C) 2006 John Wiley & Sons, Ltd.",
author = "Steven Patterson and Scullion, {Siobhan M. J.} and Janie McCluskey and Peter Flatt and Neville McClenaghan",
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Prolonged exposure to homocysteine results in diminished but reversible pancreatic beta-cell responsiveness to insulinotropic agents. / Patterson, Steven; Scullion, Siobhan M. J.; McCluskey, Janie; Flatt, Peter; McClenaghan, Neville.

In: DIABETES-METABOLISM RESEARCH AND REVIEWS, Vol. 23, No. 4, 05.2007, p. 324-334.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Prolonged exposure to homocysteine results in diminished but reversible pancreatic beta-cell responsiveness to insulinotropic agents

AU - Patterson, Steven

AU - Scullion, Siobhan M. J.

AU - McCluskey, Janie

AU - Flatt, Peter

AU - McClenaghan, Neville

PY - 2007/5

Y1 - 2007/5

N2 - Background Plasma homocysteine levels may be elevated in poorly controlled diabetes with pre-existing vascular complications and/or nephropathy. Since homocysteine has detrimental effects on a wide diversity of cell types, the present study examined the effects of long-term homocysteine exposure on the secretory function of clonal BRIN-BD11 beta-cells. Methods Acute insulin secretory function, cellular insulin content and viability of BRIN-BD11 cells were assessed following long-term (18 h) exposure to homocysteine in culture. RT-PCR and Western blot analysis were used to determine the expression of key P-cell genes and proteins. Cells were cultured for a further 18 h without homocysteine to determine any long-lasting effects. Results Homocysteine (250-1000 mu mol/L) exposure reduced insulin secretion at both moderate (5.6 mmol/L) and stimulatory (16.7 mmol/L) glucose by 48-63%. Similarly, insulin secretory responsiveness to stimulatory concentrations of alanine, arginine, 2-ketoisocaproate, tolbutamide, KCI, elevated Ca2+, forskolin and PMA, GLP-1, GIP and CCK-8 were reduced by 11-62% following culture with 100-250 mu mol/L homocysteine. These inhibitory effects could not simply be attributed to changes in cellular insulin content, cell viability, H2O2 generation or any obvious alterations of gene/protein expression for insulin, glucokinase, GLUT2, VDCC, or Kir6.2 and SUR1. Additional culture for 18 h in standard culture media after homocysteine exposure restored secretory responsiveness to all agents tested. Conclusion These findings suggest that long-term exposure to high homocysteine levels causes a reversible impairment of pancreatic beta-cell insulinotropic pathways. The in vivo actions of hyperhomocysteinaemia on islet cell function merit investigation. Copyright (C) 2006 John Wiley & Sons, Ltd.

AB - Background Plasma homocysteine levels may be elevated in poorly controlled diabetes with pre-existing vascular complications and/or nephropathy. Since homocysteine has detrimental effects on a wide diversity of cell types, the present study examined the effects of long-term homocysteine exposure on the secretory function of clonal BRIN-BD11 beta-cells. Methods Acute insulin secretory function, cellular insulin content and viability of BRIN-BD11 cells were assessed following long-term (18 h) exposure to homocysteine in culture. RT-PCR and Western blot analysis were used to determine the expression of key P-cell genes and proteins. Cells were cultured for a further 18 h without homocysteine to determine any long-lasting effects. Results Homocysteine (250-1000 mu mol/L) exposure reduced insulin secretion at both moderate (5.6 mmol/L) and stimulatory (16.7 mmol/L) glucose by 48-63%. Similarly, insulin secretory responsiveness to stimulatory concentrations of alanine, arginine, 2-ketoisocaproate, tolbutamide, KCI, elevated Ca2+, forskolin and PMA, GLP-1, GIP and CCK-8 were reduced by 11-62% following culture with 100-250 mu mol/L homocysteine. These inhibitory effects could not simply be attributed to changes in cellular insulin content, cell viability, H2O2 generation or any obvious alterations of gene/protein expression for insulin, glucokinase, GLUT2, VDCC, or Kir6.2 and SUR1. Additional culture for 18 h in standard culture media after homocysteine exposure restored secretory responsiveness to all agents tested. Conclusion These findings suggest that long-term exposure to high homocysteine levels causes a reversible impairment of pancreatic beta-cell insulinotropic pathways. The in vivo actions of hyperhomocysteinaemia on islet cell function merit investigation. Copyright (C) 2006 John Wiley & Sons, Ltd.

U2 - 10.1002/dmrr.699

DO - 10.1002/dmrr.699

M3 - Article

VL - 23

SP - 324

EP - 334

JO - Diabetes/Metabolism Research and Reviews

T2 - Diabetes/Metabolism Research and Reviews

JF - Diabetes/Metabolism Research and Reviews

SN - 1520-7552

IS - 4

ER -