Immunogold study of altered expression of some interendothelial junctional molecules in the brain blood microvessels of diabetic scrapie-infected mice

Abstract

Quantitative immunogold procedure was used to study the distribution of molecular components of interendothelial junctions in blood-brain barrier (BBB) microvessels of scrapie infected SJL/J hyperglycemic mice showing obesity and reduced glucose tolerance. Samples of brain (fronto-parietal cerebral cortex and thalamo-hypothalamic region) obtained from hyperglycemic (diabetic) mice and from non- infected, normoglycemic (non-diabetic) SJL/J mice, were processed for immunocytochemical examination. The localization of the following tight junction (TJ)-associated proteins was studied: occludin as an integral membrane (transmembrane) protein, and zonula occludens one (ZO-1) as a peripheral protein. The localization of beta-catenin as a representative of the cadherin/catenin complex that is typical for adherens junctions (AJs) also was studied. Morphometric analysis revealed that the density of immunosignals for occludin, represented by colloidal gold particles (GPs), was significantly lower in the brain microvessels of diabetic than in non-diabetic mice. No significant differences in the density of immunosignals for ZO-1 and beta-catenin between both experimental mouse groups were observed. It indicates that abnormal glucose metabolism affects mostly occludin which is believed to play a fundamental role in the maintenance of the tightness of endothelial lining in brain microvascular network and thereby in the preservation of its barrier function. These results also support the previously expressed opinion that occludin, detected with the applied morphological method, can be considered a sensitive indicator of altered molecular architecture of the interendothelial junctions due to the action of some metabolic or pathological insults.

A Three-Pore Model Describes Transport Properties of Bovine Retinal Endothelial Cells in Normal and Elevated Glucose

“…These observations are consistent with previous high-power electron micrographs of BREC monolayers grown for 30 days in HG, which revealed no significant cell damage or change in the intercellular junctions. 37 Further, Shivers 38 demonstrated that the edge and groove of the TJ revealed no alteration in freezefracture images of brain capillary endothelium of hyperglycemic lizards and Vorbrodt et al 39 were also unable to detect any changes in the ZO-1 content of brain microvessels in diabetic rats when using a quantitative immunogold procedure. While decreased expression and relocalization of ZO-1 has been observed in rat glomerular epithelial cells exposed to HG, 40 no changes have been observed in BREC monolayers.…”

Biphasic cytoarchitecture and functional changes in the BBB induced by chronic inflammatory pain

“…In the current study, however, we noted no effect of either saline or CFA-injection on ZO-1 expression or localization. Previous studies have reported ZO-1 localization within and along the interendothelial cleft, as measured by immunogold labeling (Vorbrodt and Dobrogowska, 2003;Vorbrodt et al, 2006). Therefore, ZO-1 was utilized as representative of cell-to-cell contact and the junctional space.…”

Diabetes Mellitus and Blood-Brain Barrier Dysfunction: An Overview

“…VEGF enhances and supports the translocation of GLUT-1 to the cell surface at the BBB besides promoting angiogenesis and decreasing expression of inter-endothelial tight junction proteins (e.g., ZO-1 and occludin [103]), thus increasing BBB permeability. Morphometric analysis using colloidal gold particles (GPs), showed that the immunosignal density for occludin was significantly lower in the brain microvessels of diabetic mice in comparison to controls [104]. …”