Effect of glycated insulin on the blood-brain barrier permeability: An in vitro study

Arch Biochem Biophys. 2018 Jun 1;647:54-66. doi: 10.1016/j.abb.2018.02.004. Epub 2018 Feb 11.

Abstract

Altered blood-brain barrier (BBB) permeability may contribute to pathogenesis of diabetes-related central nervous system disorders. Considering the presence of glycated insulin in plasma of type 2 diabetic patients, we hypothesized that glycated insulin could induce changes in paracellular permeability in BBB. Therefore, the authors decided to study the effect of glycated insulin on paracellular permeability in a BBB model and the change induced in insulin conformation upon glycation. In this study, the structural modification was examined by fluorescence and circular dichroism spectroscopies and dynamic light scattering. Cell proliferation and production of ROS in astrocytes and HUVEC cells were analyzed by MTT and spectrofluorometric assays, respectively. Apoptosis induction was determined and confirmed by flow cytometry and western blot analyses, respectively. The permeability was measured Lucifer yellow and FITC-Dextran. According to our results, glycated insulin presented altered conformation and more exposed hydrophobic patches than insulin. Formation of oligomeric species and advanced glycated end products (AGEs) were determined. Lower cell viability, higher apoptosis, and more ROS were detected upon treatment of cells with glycated insulin. Finally, glycated insulin led to increased Lucifer yellow and FITC-dextran transportation across the BBB model which could result from ROS producing and apoptosis-inducing activities of AGE-insulin.

Keywords: AGE products; Blood-brain barrier; Glycated insulin; Permeability; Type 2 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Astrocytes / cytology
  • Astrocytes / metabolism
  • Blood-Brain Barrier / metabolism*
  • Capillary Permeability*
  • Cell Line
  • Cell Proliferation
  • Coculture Techniques
  • Endothelial Cells / cytology
  • Endothelial Cells / metabolism
  • Glycation End Products, Advanced / metabolism*
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Insulin / analogs & derivatives*
  • Insulin / chemistry
  • Insulin / metabolism
  • Reactive Oxygen Species / metabolism

Substances

  • Glycation End Products, Advanced
  • Insulin
  • Reactive Oxygen Species
  • insulin, glycosylated