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Toxicol Appl Pharmacol. 2006 Jul 1;214(1):30-4. Epub 2006 Jan 18.

Sodium arsenite impairs insulin secretion and transcription in pancreatic beta-cells.

Author information

1
Department of Genomic Medicine and Environmental Toxicology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México.

Abstract

Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic beta-cells functions. Thus, since insulin secreted by the pancreas plays a crucial role in maintaining glucose homeostasis, our aim was to determine if sodium arsenite impairs insulin secretion and mRNA expression in single adult rat pancreatic beta-cells. Cells were treated with 0.5, 1, 2, 5 and 10 microM sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 microM) decreased beta-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 microM sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 microM treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 microM sodium arsenite for 144 h. On the other hand, insulin secretion in response to 15.6 mM glucose decreased with sodium arsenite in a dose-dependent manner in such a way that cells were no longer able to distinguish between different glucose concentrations. We also showed a significant decrease in insulin mRNA expression of cells exposed to 5 microM sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic beta-cell functions, particularly insulin synthesis and secretion.

PMID:
16413591
DOI:
10.1016/j.taap.2005.11.015
[Indexed for MEDLINE]

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