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NAD(P)H oxidase participates in the palmitate‐induced superoxide production and insulin secretion by rat pancreatic islets
Author(s) -
Graciano Maria Fernanda R.,
Santos Laila R.B.,
Curi Rui,
Carpinelli Angelo R.
Publication year - 2011
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.22432
Subject(s) - superoxide , nad+ kinase , nad(p)h oxidase , palmitic acid , pancreatic islets , oxidase test , biochemistry , chemistry , medicine , endocrinology , nadph oxidase , nicotinamide adenine dinucleotide phosphate , fatty acid , biology , insulin , islet , enzyme
Nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase complex has been shown to be involved in the process of glucose‐stimulated insulin secretion (GSIS). In this study, we examined the effect of palmitic acid on superoxide production and insulin secretion by rat pancreatic islets and the mechanism involved. Rat pancreatic islets were incubated during 1 h with 1 mM palmitate, 1% fatty acid free‐albumin, 5.6 or 10 mM glucose and in the presence of inhibitors of NAD(P)H oxidase (DPI—diphenyleneiodonium), PKC (calphostin C) and carnitine palmitoyl transferase‐I (CPT‐I) (etomoxir). Superoxide content was determined by hydroethidine assays. Palmitate increased superoxide production in the presence of 5.6 and 10 mM glucose. This effect was dependent on activation of PKC and NAD(P)H oxidase. Palmitic acid oxidation was demonstrated to contribute for the fatty acid induction of superoxide production in the presence of 5.6 mM glucose. In fact, palmitate caused p47 PHOX translocation to plasma membrane, as shown by immunohistochemistry. Exposure to palmitate for 1 h up‐regulated the protein content of p47 PHOX and the mRNA levels of p22 PHOX , gp91 PHOX , p47 PHOX , proinsulin and the G protein‐coupled receptor 40 (GPR40). Fatty acid stimulation of insulin secretion in the presence of high glucose concentration was reduced by inhibition of NAD(P)H oxidase activity. In conclusion, NAD(P)H oxidase is an important source of superoxide in pancreatic islets and the activity of NAD(P)H oxidase is involved in the control of insulin secretion by palmitate. J. Cell. Physiol. 226: 1110–1117, 2011. © 2010 Wiley‐Liss, Inc.