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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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Related in: MedlinePlus

Effect of dopamine on cellular proliferation rate of insulin-positive beta cells in isolated islets.(A) After double immunocytochemical staining, the nuclei of PCNA-positive cells appear brown (ii). (B) The proliferating insulin-positive cells (i, red) show brown-stained nuclei (ii), and the count of positive cells and calculation of the percentages of insulin-positive cells in proliferation was enabled after combining both images following digital transformation of the brown colour to blue colour (iii). 4000 cells per group were counted to obtain the statistical values. (C) Percentage of PCNA-positive cells out of the total number of cells (alpha, beta and delta cells), and (D) percentage of PCNA- and insulin-positive cells out of the total number of insulin-positive cells in the control pancreatic islets and those treated with 1μM and 10 μM dopamine **p<0.01.
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pone.0123197.g004: Effect of dopamine on cellular proliferation rate of insulin-positive beta cells in isolated islets.(A) After double immunocytochemical staining, the nuclei of PCNA-positive cells appear brown (ii). (B) The proliferating insulin-positive cells (i, red) show brown-stained nuclei (ii), and the count of positive cells and calculation of the percentages of insulin-positive cells in proliferation was enabled after combining both images following digital transformation of the brown colour to blue colour (iii). 4000 cells per group were counted to obtain the statistical values. (C) Percentage of PCNA-positive cells out of the total number of cells (alpha, beta and delta cells), and (D) percentage of PCNA- and insulin-positive cells out of the total number of insulin-positive cells in the control pancreatic islets and those treated with 1μM and 10 μM dopamine **p<0.01.

Mentions: The micrographs in Fig 4 show the PCNA-positive cells (brown-stained nuclei) and insulin-positive cells (red-stained cells). In order to facilitate the visualization of proliferative insulin-positive cells, a combination of both images was carried out following digital transformation (adobe Photoshop CS2) of the brown colour to blue (shown with arrows, Fig 4B-iii).


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)

Effect of dopamine on cellular proliferation rate of insulin-positive beta cells in isolated islets.(A) After double immunocytochemical staining, the nuclei of PCNA-positive cells appear brown (ii). (B) The proliferating insulin-positive cells (i, red) show brown-stained nuclei (ii), and the count of positive cells and calculation of the percentages of insulin-positive cells in proliferation was enabled after combining both images following digital transformation of the brown colour to blue colour (iii). 4000 cells per group were counted to obtain the statistical values. (C) Percentage of PCNA-positive cells out of the total number of cells (alpha, beta and delta cells), and (D) percentage of PCNA- and insulin-positive cells out of the total number of insulin-positive cells in the control pancreatic islets and those treated with 1μM and 10 μM dopamine **p<0.01.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123197.g004: Effect of dopamine on cellular proliferation rate of insulin-positive beta cells in isolated islets.(A) After double immunocytochemical staining, the nuclei of PCNA-positive cells appear brown (ii). (B) The proliferating insulin-positive cells (i, red) show brown-stained nuclei (ii), and the count of positive cells and calculation of the percentages of insulin-positive cells in proliferation was enabled after combining both images following digital transformation of the brown colour to blue colour (iii). 4000 cells per group were counted to obtain the statistical values. (C) Percentage of PCNA-positive cells out of the total number of cells (alpha, beta and delta cells), and (D) percentage of PCNA- and insulin-positive cells out of the total number of insulin-positive cells in the control pancreatic islets and those treated with 1μM and 10 μM dopamine **p<0.01.
Mentions: The micrographs in Fig 4 show the PCNA-positive cells (brown-stained nuclei) and insulin-positive cells (red-stained cells). In order to facilitate the visualization of proliferative insulin-positive cells, a combination of both images was carried out following digital transformation (adobe Photoshop CS2) of the brown colour to blue (shown with arrows, Fig 4B-iii).

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