Prolonged Activation of the Htr2b Serotonin Receptor Impairs Glucose Stimulated Insulin Secretion and Mitochondrial Function in MIN6 Cells

PLoS One. 2017 Jan 27;12(1):e0170213. doi: 10.1371/journal.pone.0170213. eCollection 2017.

Abstract

Aims: Pancreatic β-cells synthesize and release serotonin (5 hydroxytryptamine, 5HT); however, the role of 5HT receptors on glucose stimulated insulin secretion (GSIS) and the mechanisms mediating this function is not fully understood. The aims of this study were to determine the expression profile of 5HT receptors in murine MIN6 β-cells and to examine the effects of pharmacological activation of 5HT receptor Htr2b on GSIS and mitochondrial function.

Materials and methods: mRNA levels of 5HT receptors in MIN6 cells were quantified by RT qPCR. GSIS was assessed in MIN6 cells in response to global serotonergic activation with 5HT and pharmacological Htr2b activation or inhibition with BW723C86 or SB204741, respectively. In response to Htr2b activation also was evaluated the mRNA and protein levels of PGC1α and PPARy by RT-qPCR and western blotting and mitochondrial function by oxygen consumption rate (OCR) and ATP cellular content.

Results: We found that mRNA levels of most 5HT receptors were either very low or undetectable in MIN6 cells. By contrast, Htr2b mRNA was present at moderate levels in these cells. Preincubation (6 h) of MIN6 cells with 5HT or BW723C86 reduced GSIS and the effect of 5HT was prevented by SB204741. Preincubation with BW723C86 increased PGC1α and PPARy mRNA and protein levels and decreased mitochondrial respiration and ATP content in MIN6 cells.

Conclusions: Our results indicate that prolonged Htr2b activation in murine β-cells decreases glucose-stimulated insulin secretion and mitochondrial activity by mechanisms likely dependent on enhanced PGC1α/PPARy expression.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Cell Line
  • Gene Expression Regulation / drug effects
  • Glucose / metabolism
  • Humans
  • Indoles / pharmacology
  • Insulin / genetics
  • Insulin / metabolism*
  • Insulin-Secreting Cells / metabolism
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism
  • Mice
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Oxygen Consumption / genetics
  • PPAR gamma / biosynthesis
  • PPAR gamma / genetics*
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / biosynthesis
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / genetics*
  • Receptors, Serotonin / biosynthesis
  • Receptors, Serotonin / genetics*
  • Serotonin / genetics
  • Serotonin / metabolism*
  • Serotonin / pharmacology
  • Thiophenes / pharmacology
  • Urea / analogs & derivatives
  • Urea / pharmacology

Substances

  • 1-(5-(2-thenyloxy)-1H-indol-3-yl)propan-2-amine
  • Indoles
  • Insulin
  • N-(1-methyl-5-indolyl)-N'-(3-methyl-5-isothiazolyl)urea
  • PPAR gamma
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Ppargc1a protein, mouse
  • Receptors, Serotonin
  • Thiophenes
  • Serotonin
  • Adenosine Triphosphate
  • Urea
  • Glucose

Grant support

This research was funded by “Fondo Nacional de Desarrollo Científico y Tecnológico” grants; 1141134 (VC), 1120586 (JLS), 1120443 (CC), 1160332 (CC), 1130217 (JEG). “Fondo de financiamiento de Centros de Investigación en Áreas Prioritarias” grant 15150012 (CC). “Comisión Nacional de Investigación en Ciencia y Tecnología”; doctoral scholarship 21140087 (LRC), postdoctoral fellowship 3160226 (RBS), postdoctoral fellowship 3140458 (FJ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.