Optimising a Method to Assess CNS Barrier Integrity and its Application to a Drosophila Model of Glial Tauopathy

Abstract

The vertebrate blood brain barrier (BBB) allows for optimal functioning of billions of neurons and glia by regulating the diffusion and transport of toxins, inflammatory mediators, ions, and metabolites into and out of the central nervous system (CNS). While the BBB exists primarily as a result of specialised properties of CNS endothelial cells, its function is facilitated by glial cells lining the cerebral vasculature. In organisms that do not possess a vascularized circulatory system, such as Drosophila melanogaster, two layers of glial cells themselves establish a compound barrier that is molecularly and functionally homologous to the vertebrate BBB. As such, Drosophila is increasingly recognised as a viable model for investigating BBB function and the factors that influence it. In this study, we developed optimal approaches to dissection and analysis procedures to assess the integrity of this barrier. We then applied these approaches to examine the effect of glial tau expression on CNS barrier disruption post traumatic injury. We hypothesised that glial tau expression would exacerbate barrier disruption post traumatic injury. However, we failed to support this hypothesis after examining the effects of both pan-glial and barrier-associated glial cell tau expression. As such, this work functions to elucidate our current understanding of the optimal methods to assess CNS barrier function and effect of glial tau expression in a D. melanogaster model.