The neurocentric theory dismissed for decades the role of glia in information handling within the central nervous system (CNS). Nevertheless, almost 3 decades ago, this started to change and today astrocytes are considered relevant players for this function. Astrocytes “listen” to neuronal communication, regulate it, and respond at the cellular and synctitial level. Ionotropic glutamate NMDA receptor (NMDAR) is critical in CNS. It mediates synaptic neuronal communication and it is involved in different mechanisms. However, NMDAR is also expressed by astrocytes, but its functional role in these cells has not been deeply investigated and has been a matter of debate in the last decades. In this chapter, we briefly outline NMDAR intracellular transduction pathways initiated by Ca2+ flux. Then, we review chronologically NMDAR expression and function in astrocytes that have been a source of controversies and apparent contradictions. Finally, some insights are presented regarding NMDAR in astrocytes in the context of the tripartite synapse concept and the recently described Ca2+ flux–independent metabotropic-like NMDAR function in astrocytes. Given the complex molecular nature of NMDAR, its critical role, and the relevance of astrocytes, the study of astrocytic NMDAR promises to provide further understanding of CNS physiology and pathology.
Part of the book: Astrocyte