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Arachidonic acid actions on functional integrity and attenuation of the negative effects of palmitic acid in a clonal pancreatic β-cell line.

Keane DC, Takahashi HK, Dhayal S, Morgan NG, Curi R, Newsholme P - Clin. Sci. (2011)

Bottom Line: Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects.AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells.These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the 'lipotoxic' environment commonly associated with Type 2 diabetes mellitus.

View Article: PubMed Central - PubMed

Affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute and UCD Institute of Sport and Health, UCD Dublin, Belfield, Dublin 4, Ireland.

ABSTRACT
Chronic exposure of pancreatic β-cells to saturated non-esterified fatty acids can lead to inhibition of insulin secretion and apoptosis. Several previous studies have demonstrated that saturated fatty acids such as PA (palmitic acid) are detrimental to β-cell function compared with unsaturated fatty acids. In the present study, we describe the effect of the polyunsaturated AA (arachidonic acid) on the function of the clonal pancreatic β-cell line BRIN-BD11 and demonstrate AA-dependent attenuation of PA effects. When added to β-cell incubations at 100 μM, AA can stimulate cell proliferation and chronic (24 h) basal insulin secretion. Microarray analysis and/or real-time PCR indicated significant AA-dependent up-regulation of genes involved in proliferation and fatty acid metabolism [e.g. Angptl (angiopoietin-like protein 4), Ech1 (peroxisomal Δ3,5,Δ2,4-dienoyl-CoA isomerase), Cox-1 (cyclo-oxygenase-1) and Cox-2, P<0.05]. Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects. Moreover, concomitant incubation of AA with PA dose-dependently attenuated the detrimental effects of the saturated fatty acid, so reducing apoptosis and decreasing parameters of oxidative stress [ROS (reactive oxygen species) and NO levels] while improving the GSH/GSSG ratio. AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells. These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the 'lipotoxic' environment commonly associated with Type 2 diabetes mellitus.

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Related in: MedlinePlus

Effect of PA or AA on expression levels of Cox-1 and Cox-2BRIN-BD11 cells were incubated and in the absence or presence of 100 μM AA and in the absence or presence of increasing concentrations of PA as indicated for 24 h. After this time, the cells were harvested, and the expression levels of Cox-1 (A) or Cox-2 (B) were determined by real-time PCR. Expression levels were subsequently normalized to Gapdh (glyceraldehyde-3-phosphate dehydrogenase) expression. Results are means±S.E.M. for three individual experiments. A significant improvement in cell viability (*P<0.05 and **P<0.001) was observed at all concentrations of AA tested.
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Figure 5: Effect of PA or AA on expression levels of Cox-1 and Cox-2BRIN-BD11 cells were incubated and in the absence or presence of 100 μM AA and in the absence or presence of increasing concentrations of PA as indicated for 24 h. After this time, the cells were harvested, and the expression levels of Cox-1 (A) or Cox-2 (B) were determined by real-time PCR. Expression levels were subsequently normalized to Gapdh (glyceraldehyde-3-phosphate dehydrogenase) expression. Results are means±S.E.M. for three individual experiments. A significant improvement in cell viability (*P<0.05 and **P<0.001) was observed at all concentrations of AA tested.

Mentions: The incubation of BRIN-BD11 cells with PA for 24 h did not change the expression levels of Cox-1 or Cox-2 mRNA (Figure 5). Incubation with AA (100 μM) alone or in combination with PA, significantly increased the expression of both enzymes when compared with the no-AA control. Additionally, concomitant incubation of PA and AA (100 μM) for 24 h significantly reduced the expression levels of Cox-1 and Cox-2 mRNA, compared with AA alone, in a PA-concentration-dependent manner.


Arachidonic acid actions on functional integrity and attenuation of the negative effects of palmitic acid in a clonal pancreatic β-cell line.

Keane DC, Takahashi HK, Dhayal S, Morgan NG, Curi R, Newsholme P - Clin. Sci. (2011)

Effect of PA or AA on expression levels of Cox-1 and Cox-2BRIN-BD11 cells were incubated and in the absence or presence of 100 μM AA and in the absence or presence of increasing concentrations of PA as indicated for 24 h. After this time, the cells were harvested, and the expression levels of Cox-1 (A) or Cox-2 (B) were determined by real-time PCR. Expression levels were subsequently normalized to Gapdh (glyceraldehyde-3-phosphate dehydrogenase) expression. Results are means±S.E.M. for three individual experiments. A significant improvement in cell viability (*P<0.05 and **P<0.001) was observed at all concentrations of AA tested.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2990202&req=5

Figure 5: Effect of PA or AA on expression levels of Cox-1 and Cox-2BRIN-BD11 cells were incubated and in the absence or presence of 100 μM AA and in the absence or presence of increasing concentrations of PA as indicated for 24 h. After this time, the cells were harvested, and the expression levels of Cox-1 (A) or Cox-2 (B) were determined by real-time PCR. Expression levels were subsequently normalized to Gapdh (glyceraldehyde-3-phosphate dehydrogenase) expression. Results are means±S.E.M. for three individual experiments. A significant improvement in cell viability (*P<0.05 and **P<0.001) was observed at all concentrations of AA tested.
Mentions: The incubation of BRIN-BD11 cells with PA for 24 h did not change the expression levels of Cox-1 or Cox-2 mRNA (Figure 5). Incubation with AA (100 μM) alone or in combination with PA, significantly increased the expression of both enzymes when compared with the no-AA control. Additionally, concomitant incubation of PA and AA (100 μM) for 24 h significantly reduced the expression levels of Cox-1 and Cox-2 mRNA, compared with AA alone, in a PA-concentration-dependent manner.

Bottom Line: Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects.AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells.These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the 'lipotoxic' environment commonly associated with Type 2 diabetes mellitus.

View Article: PubMed Central - PubMed

Affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute and UCD Institute of Sport and Health, UCD Dublin, Belfield, Dublin 4, Ireland.

ABSTRACT
Chronic exposure of pancreatic β-cells to saturated non-esterified fatty acids can lead to inhibition of insulin secretion and apoptosis. Several previous studies have demonstrated that saturated fatty acids such as PA (palmitic acid) are detrimental to β-cell function compared with unsaturated fatty acids. In the present study, we describe the effect of the polyunsaturated AA (arachidonic acid) on the function of the clonal pancreatic β-cell line BRIN-BD11 and demonstrate AA-dependent attenuation of PA effects. When added to β-cell incubations at 100 μM, AA can stimulate cell proliferation and chronic (24 h) basal insulin secretion. Microarray analysis and/or real-time PCR indicated significant AA-dependent up-regulation of genes involved in proliferation and fatty acid metabolism [e.g. Angptl (angiopoietin-like protein 4), Ech1 (peroxisomal Δ3,5,Δ2,4-dienoyl-CoA isomerase), Cox-1 (cyclo-oxygenase-1) and Cox-2, P<0.05]. Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects. Moreover, concomitant incubation of AA with PA dose-dependently attenuated the detrimental effects of the saturated fatty acid, so reducing apoptosis and decreasing parameters of oxidative stress [ROS (reactive oxygen species) and NO levels] while improving the GSH/GSSG ratio. AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells. These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the 'lipotoxic' environment commonly associated with Type 2 diabetes mellitus.

Show MeSH
Related in: MedlinePlus