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Pancreatic β-cell dysfunction, expression of iNOS and the effect of phosphodiesterase inhibitors in human pancreatic islets of type 2 diabetes.

Jabar Muhammed, Sarheed LU ; Lundquist, Ingmar LU and Salehi, S Albert LU (2012) In Diabetes, Obesity and Metabolism 14(11). p.1010-1019
Abstract
AIMS:

Induction of iNOS in pancreatic islets leads to exaggerated NO production associated with dysfunctional β-cells. We examined insulin secretion, iNOS expression and its relation to the cAMP system in islets from human type 2 diabetes.



METHODS:

Insulin, glucagon and cAMP were analyzed by RIA; iNOS or PDE expression by qPCR, Western blot and confocal microscopy; cell viability by MTS.



RESULTS: Diabetic islets displayed impaired insulin and glucagon responses to glucose, disturbed cAMP generation, and high iNOS mRNA and protein expression. Confocal microscopy showed iNOS protein expression in diabetic islets being confined to insulin, glucagon and somatostatin cells. Culture of... (More)
AIMS:

Induction of iNOS in pancreatic islets leads to exaggerated NO production associated with dysfunctional β-cells. We examined insulin secretion, iNOS expression and its relation to the cAMP system in islets from human type 2 diabetes.



METHODS:

Insulin, glucagon and cAMP were analyzed by RIA; iNOS or PDE expression by qPCR, Western blot and confocal microscopy; cell viability by MTS.



RESULTS: Diabetic islets displayed impaired insulin and glucagon responses to glucose, disturbed cAMP generation, and high iNOS mRNA and protein expression. Confocal microscopy showed iNOS protein expression in diabetic islets being confined to insulin, glucagon and somatostatin cells. Culture of diabetic islets at 5.5 mmol/l glucose with dibutyryl-cAMP (Bt(2) -cAMP) for 24 h was accompanied by marked suppression of iNOS mRNA, reduced nitrite production and increased insulin secretion. Diabetic islets displayed marked increase in PDE3A and PDE3B mRNA expression. Short-time incubation of diabetic islets showed, among the PDE inhibitors tested, cilostazol being most favourable to increase insulin secretion. Diabetic islets were most susceptible to long-term (72 h) culture at high glucose (20 mmol/l) reacting with increased apoptosis. Bt(2) -cAMP and the PDE inhibitors cilostazol, milrinone and IBMX efficiently increased cell viability at high glucose during culture. Defective glucose-stimulated insulin release upon induction of iNOS was restored by iNOS inhibitor aminoguanidine.



CONCLUSION:

Our results suggest that in islets from type 2 diabetes, stimulatory effects in certain cAMP-compartments induced by PDE inhibitors might play a central role in the suppression of iNOS, resulting in increased β-cell viability and improved secretory response to glucose. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
PKA system, cAMP, iNOS expression, insulin secretion, phosphodiesterase, type 2 diabetic islets
in
Diabetes, Obesity and Metabolism
volume
14
issue
11
pages
1010 - 1019
publisher
Wiley-Blackwell
external identifiers
  • wos:000309453900006
  • pmid:22687049
  • scopus:84867142480
ISSN
1462-8902
DOI
10.1111/j.1463-1326.2012.01632.x
language
English
LU publication?
yes
id
9d01a141-bbf9-4b10-9aa5-33d8b4928be8 (old id 2859583)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/22687049?dopt=Abstract
date added to LUP
2012-07-04 12:39:15
date last changed
2017-08-27 03:44:43
@article{9d01a141-bbf9-4b10-9aa5-33d8b4928be8,
  abstract     = {AIMS:<br/><br>
Induction of iNOS in pancreatic islets leads to exaggerated NO production associated with dysfunctional β-cells. We examined insulin secretion, iNOS expression and its relation to the cAMP system in islets from human type 2 diabetes. <br/><br>
<br/><br>
METHODS: <br/><br>
Insulin, glucagon and cAMP were analyzed by RIA; iNOS or PDE expression by qPCR, Western blot and confocal microscopy; cell viability by MTS. <br/><br>
<br/><br>
RESULTS: Diabetic islets displayed impaired insulin and glucagon responses to glucose, disturbed cAMP generation, and high iNOS mRNA and protein expression. Confocal microscopy showed iNOS protein expression in diabetic islets being confined to insulin, glucagon and somatostatin cells. Culture of diabetic islets at 5.5 mmol/l glucose with dibutyryl-cAMP (Bt(2) -cAMP) for 24 h was accompanied by marked suppression of iNOS mRNA, reduced nitrite production and increased insulin secretion. Diabetic islets displayed marked increase in PDE3A and PDE3B mRNA expression. Short-time incubation of diabetic islets showed, among the PDE inhibitors tested, cilostazol being most favourable to increase insulin secretion. Diabetic islets were most susceptible to long-term (72 h) culture at high glucose (20 mmol/l) reacting with increased apoptosis. Bt(2) -cAMP and the PDE inhibitors cilostazol, milrinone and IBMX efficiently increased cell viability at high glucose during culture. Defective glucose-stimulated insulin release upon induction of iNOS was restored by iNOS inhibitor aminoguanidine. <br/><br>
<br/><br>
CONCLUSION: <br/><br>
Our results suggest that in islets from type 2 diabetes, stimulatory effects in certain cAMP-compartments induced by PDE inhibitors might play a central role in the suppression of iNOS, resulting in increased β-cell viability and improved secretory response to glucose.},
  author       = {Jabar Muhammed, Sarheed and Lundquist, Ingmar and Salehi, S Albert},
  issn         = {1462-8902},
  keyword      = {PKA system,cAMP,iNOS expression,insulin secretion,phosphodiesterase,type 2 diabetic islets},
  language     = {eng},
  number       = {11},
  pages        = {1010--1019},
  publisher    = {Wiley-Blackwell},
  series       = {Diabetes, Obesity and Metabolism},
  title        = {Pancreatic β-cell dysfunction, expression of iNOS and the effect of phosphodiesterase inhibitors in human pancreatic islets of type 2 diabetes.},
  url          = {http://dx.doi.org/10.1111/j.1463-1326.2012.01632.x},
  volume       = {14},
  year         = {2012},
}