An abundant population of glial cells in the central nervous system (CNS) is identified by the specific expression of the NG2 chondroitin sulphate proteoglycan (CSPG) and are termed NG. NG2-slia are phenotypically distinct from astrocytes, oligodendrocytes, ependyma and microglia, and represent a fifth major type of glia in the brain. Generally, NG2-glia have been considered to be oligodendrocyte progenitor cells (OPCs), but there is evidence that NG2-glia possess neural stem cell-like properties, being able to generate oligodendrocytes, astrocytes and neurons. In addition, NG2-glia respond to different types of brain injury by a rapid and extensive proliferation, or gliosis, and contribute to the axon growth inhibitory glial scar and regeneration of oligodendrocytes. A notable feature of NG2-glia is that they have complex multibranched process fields that form multiple glutamatergic synaptic contacts with neurons. So far, the function of NG2-glial glutamatergic 'synapses' is unresolved. The overall aim of this thesis was to test the hypothesis that NG2-glia may be important for the stabilization and integrity of synapses, and that glutamate released at these synapses may regulate the proliferation and differentiation capacity of NG2-glia.