Functional properties of glycine receptors and their expression in oligodendroglial cells

Abstract

This study is the start of a new research line investigating the role of neurotransmitters in neuroglial cell functions, with specific attention for extrasynaptic function of neurotransmitters. The first part of this thesis will focus on the function of glycine receptors themselves, with a special interest in the functioning of glycine receptors containing α2 subunits. This subunit is mainly expressed during development and is an interesting candidate for transducing extrasynaptic signals of glycine during the development of different neuronal and glial cell types. Inhibitory neurotransmitter signalling, and glycine signalling in particular, will be introduced in chapter 2. In chapter 3 the properties of the different components of picrotoxin, a widely used pharmacological tool in glycine receptor research, will be investigated. This results in a proposed model for blocking mechanisms by picrotoxinin and picrotin, the picrotoxin components, on α2 glycine receptors. The results provide further insight in glycine receptor kinetics and pharmacology. In chapter 4 data will be presented which indicate how the functional expression of the β subunit influences α2 glycine receptor properties. The expression of the β subunit increases during development and the hypothesis is that its incorporation into heteromeric α2β glycine receptors is necessary for the α2 glycine receptor to function in a synaptic context. The second part of the thesis investigates an oligodendroglial cell line (OLN-93) in light of the study of influence of neurotransmitter receptors on oligodendrocyte cell function. In chapter 5, the oligodendroglial development will be introduced, with special attention for the role of electrophysiological properties herein. Chapter 6 looks at neurotransmitter receptor expression by this cell line and correlates it to the expression of neurotransmitters in a primary oligodendroglial culture derived from rat. Given the marked differences between primary cells and OLN-93, chapter 7 characterizes the developmental stage of the OLN-93 cell line using functional and biochemical tools. This insight is necessary to correctly use the cell line in future studies and to be able to interpret results from it in light of developmental studies of oligodendroglial cells. Altogether the work presented provides tools for further research in the domain of extrasynaptic neurotransmitter roles, especially in the field of glial cell biology. Eventually it is our hope that insight into these mechanisms will subsequently lead to insight in disease mechanisms such as in Multiple Sclerosis, where oligodendrocytes are damaged and fail to repair sufficiently.