Glucose Transporter Distribution in the Vessels of the Central Nervous System of the Axolotl Ambystoma mexicanum (Urodela: Ambystomatidae)

Abstract

The GLUT-1 isoform of the glucose transporter is commonly considered a reliable molecular marker of blood-brain barrier endothelia in the neural vasculature organized in a three-dimensional network of single vessels. The central nervous system of the axolotl Ambystoma mexicanum is characterized by a vascular architecture that contains both single and paired vessels. The presence and distribution of the GLUT-1 transporter are studied in this urodele using both immunoperoxidase histochemistry and immunogold technique. Light microscopy reveals immunopositivity in both parenchymal and meningeal vessels. The transverse-sectioned pairs of vessels do not show the same size. Furthermore, in the same pair, the two elements often differ in diameter. The main regions of the central nervous system show a different percentage of the paired structures. Only immunogold cytochemistry reveals different staining intensity in the two adjoined elements of a vascular pair. Colloidal gold particles show an asymmetric distribution in the endothelia of both single and paired vessels. These particles are more numerous on the abluminal surface than on the luminal one. The particle density is calculated in both vascular types. The different values could indicate functional differences between single and paired vessels and between the two adjoined elements of a pair, regarding glucose transport.