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Dopamine modulates insulin release and is involved in the survival of rat pancreatic beta cells.

Garcia Barrado MJ, Iglesias Osma MC, Blanco EJ, Carretero Hernández M, Sánchez Robledo V, Catalano Iniesta L, Carrero S, Carretero J - PLoS ONE (2015)

Bottom Line: The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment.The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h.In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Pharmacology, Faculty of Medicine, University of Salamanca, Salamanca, Spain; Laboratory of Neuroendocrinology, Institute of Neurosciences of Castilla y León, and Laboratory of Neuroendocrinology and Obesity of IBSAL, University of Salamanca, Salamanca, Spain.

ABSTRACT
The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets.

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Apoptosis of beta cells treated with dopamine after labelling for active Caspase-3.Images obtained by double immunohistochemistry for insulin (A) (brown) and active caspase-3 (B) (fluorescence in red) in control islets (I), and dopamine-treated islets at 1, 3, 6 and 12 h (II). As can be observed in the micrographs there is minimal reaction in islets with glucose alone (BI-1, 2, 3, and 4). Treatment with dopamine induced positivity for caspase-3 (B-II 1, 2, 3 and 4), The intensity of the fluorescent signal was increased according to increase the time point of study. (C) Plot showing the increase induced by dopamine 1μM in the percentage active caspase-3 positive cells from total of insulin positive cells at the different time-points assayed. From 1 to 12 hours of treatment a significant increase (*p<0.05, **p<0.01 with respect to their respective controls) was observed. Scale bar: 50 μm.
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pone.0123197.g005: Apoptosis of beta cells treated with dopamine after labelling for active Caspase-3.Images obtained by double immunohistochemistry for insulin (A) (brown) and active caspase-3 (B) (fluorescence in red) in control islets (I), and dopamine-treated islets at 1, 3, 6 and 12 h (II). As can be observed in the micrographs there is minimal reaction in islets with glucose alone (BI-1, 2, 3, and 4). Treatment with dopamine induced positivity for caspase-3 (B-II 1, 2, 3 and 4), The intensity of the fluorescent signal was increased according to increase the time point of study. (C) Plot showing the increase induced by dopamine 1μM in the percentage active caspase-3 positive cells from total of insulin positive cells at the different time-points assayed. From 1 to 12 hours of treatment a significant increase (*p<0.05, **p<0.01 with respect to their respective controls) was observed. Scale bar: 50 μm.

Mentions: Fig 5 shows images obtained with double immunohistochemistry for insulin (brown, Fig 5A) and active Caspase-3 (fluorescence in red, Fig 5B) where practically the absence of active Caspase-3 can be observed in control islets at all times (Fig 5B-I), together with the induction of the expression of active Caspase-3 after treatment with dopamine from 1 h up to 12 h (Fig 5B-II). In the control islets, the percentage of active Caspase-3 positive cells from total of insulin positive cells (Fig 5C) was imperceptible and similar for all time-points assayed. In the islets treated with dopamine, the percentages of active Caspase-3 positive cells from total of insulin positive cells were increased for all doses and time-points assayed (p< 0.05 at 1, 3 and p<0.01 at 6 at 12 hours versus controls).


Dopamine modulates insulin release and is involved in the survival of rat pancreatic beta cells.

Garcia Barrado MJ, Iglesias Osma MC, Blanco EJ, Carretero Hernández M, Sánchez Robledo V, Catalano Iniesta L, Carrero S, Carretero J - PLoS ONE (2015)

Apoptosis of beta cells treated with dopamine after labelling for active Caspase-3.Images obtained by double immunohistochemistry for insulin (A) (brown) and active caspase-3 (B) (fluorescence in red) in control islets (I), and dopamine-treated islets at 1, 3, 6 and 12 h (II). As can be observed in the micrographs there is minimal reaction in islets with glucose alone (BI-1, 2, 3, and 4). Treatment with dopamine induced positivity for caspase-3 (B-II 1, 2, 3 and 4), The intensity of the fluorescent signal was increased according to increase the time point of study. (C) Plot showing the increase induced by dopamine 1μM in the percentage active caspase-3 positive cells from total of insulin positive cells at the different time-points assayed. From 1 to 12 hours of treatment a significant increase (*p<0.05, **p<0.01 with respect to their respective controls) was observed. Scale bar: 50 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401745&req=5

pone.0123197.g005: Apoptosis of beta cells treated with dopamine after labelling for active Caspase-3.Images obtained by double immunohistochemistry for insulin (A) (brown) and active caspase-3 (B) (fluorescence in red) in control islets (I), and dopamine-treated islets at 1, 3, 6 and 12 h (II). As can be observed in the micrographs there is minimal reaction in islets with glucose alone (BI-1, 2, 3, and 4). Treatment with dopamine induced positivity for caspase-3 (B-II 1, 2, 3 and 4), The intensity of the fluorescent signal was increased according to increase the time point of study. (C) Plot showing the increase induced by dopamine 1μM in the percentage active caspase-3 positive cells from total of insulin positive cells at the different time-points assayed. From 1 to 12 hours of treatment a significant increase (*p<0.05, **p<0.01 with respect to their respective controls) was observed. Scale bar: 50 μm.
Mentions: Fig 5 shows images obtained with double immunohistochemistry for insulin (brown, Fig 5A) and active Caspase-3 (fluorescence in red, Fig 5B) where practically the absence of active Caspase-3 can be observed in control islets at all times (Fig 5B-I), together with the induction of the expression of active Caspase-3 after treatment with dopamine from 1 h up to 12 h (Fig 5B-II). In the control islets, the percentage of active Caspase-3 positive cells from total of insulin positive cells (Fig 5C) was imperceptible and similar for all time-points assayed. In the islets treated with dopamine, the percentages of active Caspase-3 positive cells from total of insulin positive cells were increased for all doses and time-points assayed (p< 0.05 at 1, 3 and p<0.01 at 6 at 12 hours versus controls).

Bottom Line: The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment.The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h.In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Pharmacology, Faculty of Medicine, University of Salamanca, Salamanca, Spain; Laboratory of Neuroendocrinology, Institute of Neurosciences of Castilla y León, and Laboratory of Neuroendocrinology and Obesity of IBSAL, University of Salamanca, Salamanca, Spain.

ABSTRACT
The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets.

Show MeSH
Related in: MedlinePlus