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Inhibition of Calcium Influx Reduces Dysfunction and Apoptosis in Lipotoxic Pancreatic β-Cells via Regulation of Endoplasmic Reticulum Stress.

Zhou Y, Sun P, Wang T, Chen K, Zhu W, Wang H - PLoS ONE (2015)

Bottom Line: And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated.It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis.Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.

ABSTRACT
Lipotoxicity plays an important role in pancreatic β-cell failure during the development of type 2 diabetes. Prolonged exposure of β-cells to elevated free fatty acids level could cause deterioration of β-cell function and induce cell apoptosis. Therefore, inhibition of fatty acids-induced β-cell dysfunction and apoptosis might provide benefit for the therapy of type 2 diabetes. The present study examined whether regulation of fatty acids-triggered calcium influx could protect pancreatic β-cells from lipotoxicity. Two small molecule compounds, L-type calcium channel blocker nifedipine and potassium channel activator diazoxide were used to inhibit palmitic acid-induced calcium influx. And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated. It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis. Meanwhile, the impaired insulin secretion was also recovered to varying degrees by these two compounds. Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells. More importantly, it suggested that regulation of calcium influx by small molecule compounds might provide benefits for the prevention and therapy of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus

Nifedipine and diazoxide inhibited PA-stimulated Ca2+ release.(A) Pre-incubated of nifedipine dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. (B) There was no significant change in PA-induced Ca2+ release between diazoxide co-treated and PA-treated alone group. The Ca2+ mobilization buffer did not contain glucose. (C) In the presence of 25.5 mM glucose, pre-incubated of diazoxide dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6.
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pone.0132411.g004: Nifedipine and diazoxide inhibited PA-stimulated Ca2+ release.(A) Pre-incubated of nifedipine dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. (B) There was no significant change in PA-induced Ca2+ release between diazoxide co-treated and PA-treated alone group. The Ca2+ mobilization buffer did not contain glucose. (C) In the presence of 25.5 mM glucose, pre-incubated of diazoxide dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6.

Mentions: To observe the effect of nifedipine and diazoxide on PA-stimulated Ca2+ release in MIN6 β-cells, the Fluo-4 dye was used to determine intracellular Ca2+ concentrations. It was found that nifedipine, a L-type Ca2+ channel blocker, produced a direct concentration dependent inhibition of PA-stimulated Ca2+ release in MIN6 cells (Fig 4A). And diazoxide, an ATP-sensitive K+ channel opener, could inhibit glucose-induced increasing of ATP concentration, thereby reducing membrane hyperpolarization and activation of voltage-dependent Ca2+ channel [20]. Thus, we also detected the effect of diazoxide on PA-stimulated Ca2+ release in MIN6 cells. However, diazoxide did not alter Ca2+ response to PA in MIN6 without glucose during monitoring time (Fig 4B). As diazoxide exerted protective effects on PA-impaired MIN6 cells, we then detected the PA-stimulated Ca2+ release in the presence of 25.5 mM glucose, which was the concentration of glucose used in common culture medium of MIN6 cells. It was found that diazoxide at 100 μM could slightly suppress PA-induced Ca2+ release in MIN6 cells, while 200 and 300 μM diazoxide significantly inhibited Ca2+ release in the presence of glucose.


Inhibition of Calcium Influx Reduces Dysfunction and Apoptosis in Lipotoxic Pancreatic β-Cells via Regulation of Endoplasmic Reticulum Stress.

Zhou Y, Sun P, Wang T, Chen K, Zhu W, Wang H - PLoS ONE (2015)

Nifedipine and diazoxide inhibited PA-stimulated Ca2+ release.(A) Pre-incubated of nifedipine dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. (B) There was no significant change in PA-induced Ca2+ release between diazoxide co-treated and PA-treated alone group. The Ca2+ mobilization buffer did not contain glucose. (C) In the presence of 25.5 mM glucose, pre-incubated of diazoxide dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4492560&req=5

pone.0132411.g004: Nifedipine and diazoxide inhibited PA-stimulated Ca2+ release.(A) Pre-incubated of nifedipine dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. (B) There was no significant change in PA-induced Ca2+ release between diazoxide co-treated and PA-treated alone group. The Ca2+ mobilization buffer did not contain glucose. (C) In the presence of 25.5 mM glucose, pre-incubated of diazoxide dose-dependently inhibited 0.5 mM PA-stimulated Ca2+ release in MIN6 cells. * p<0.05; ** p<0.01; *** p<0.001 denote significant difference versus the PA-treated alone group, n = 6.
Mentions: To observe the effect of nifedipine and diazoxide on PA-stimulated Ca2+ release in MIN6 β-cells, the Fluo-4 dye was used to determine intracellular Ca2+ concentrations. It was found that nifedipine, a L-type Ca2+ channel blocker, produced a direct concentration dependent inhibition of PA-stimulated Ca2+ release in MIN6 cells (Fig 4A). And diazoxide, an ATP-sensitive K+ channel opener, could inhibit glucose-induced increasing of ATP concentration, thereby reducing membrane hyperpolarization and activation of voltage-dependent Ca2+ channel [20]. Thus, we also detected the effect of diazoxide on PA-stimulated Ca2+ release in MIN6 cells. However, diazoxide did not alter Ca2+ response to PA in MIN6 without glucose during monitoring time (Fig 4B). As diazoxide exerted protective effects on PA-impaired MIN6 cells, we then detected the PA-stimulated Ca2+ release in the presence of 25.5 mM glucose, which was the concentration of glucose used in common culture medium of MIN6 cells. It was found that diazoxide at 100 μM could slightly suppress PA-induced Ca2+ release in MIN6 cells, while 200 and 300 μM diazoxide significantly inhibited Ca2+ release in the presence of glucose.

Bottom Line: And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated.It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis.Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.

ABSTRACT
Lipotoxicity plays an important role in pancreatic β-cell failure during the development of type 2 diabetes. Prolonged exposure of β-cells to elevated free fatty acids level could cause deterioration of β-cell function and induce cell apoptosis. Therefore, inhibition of fatty acids-induced β-cell dysfunction and apoptosis might provide benefit for the therapy of type 2 diabetes. The present study examined whether regulation of fatty acids-triggered calcium influx could protect pancreatic β-cells from lipotoxicity. Two small molecule compounds, L-type calcium channel blocker nifedipine and potassium channel activator diazoxide were used to inhibit palmitic acid-induced calcium influx. And whether the compounds could reduce palmitic acid-induced β-cell failure and the underlying mechanism were also investigated. It was found that both nifedipine and diazoxide protected MIN6 pancreatic β-cells and primary cultured murine islets from palmitic acid-induced apoptosis. Meanwhile, the impaired insulin secretion was also recovered to varying degrees by these two compounds. Our results verified that nifedipine and diazoxide could reduce palmitic acid-induced endoplasmic reticulum stress to generate protective effects on pancreatic β-cells. More importantly, it suggested that regulation of calcium influx by small molecule compounds might provide benefits for the prevention and therapy of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus