The role of glial cells in synaptic function

Abstract

Glial cells represent the most abundant cell population in the central nervous system and for years they have been thought to provide just structural and trophic support to neurons. Recently, several studies were performed, leading to the identi¢cation of an active interaction between glia and neurons. This paper focuses on the role played by glial cells at the level of the synapse, reviewing recent data de¢ning how glia is determinant in synaptogenesis, in the modulation of fully working synaptic contacts and in synaptic plasticity.

Cytoskeletal Genes Regulation by Chronic Morphine Treatment in Rat Striatum

“…Markers of neuronal plasticity like growthassociated protein-43 (Gap43) and activity-regulated cytoskeleton-associated protein (Arc); of intracellular traficking, like dynamin, clathrin heavy chain (Cltc) and filamin a (Flna) or of microtubule assembly and stabilization like, atubulin, stathmin, Stop, and Tau were chosen. Since active interactions between neuron and glia are important for synaptogenesis and synaptic plasticity (review in Bacci et al, 1999), we also studied glial fibrillary acidic protein (Gfap), a marker of astroglial cells. Modulations of mRNA and proteins levels were observed following chronic morphine administration supporting the hypothesis of a relationship between cytoskeleton modifications and long-lasting actions of morphine.…”

The endocannabinoid system in normal and pathological brain ageing

“…Microglial cells originate from a macrophage lineage and they are the main form of active immune defence within the central nervous system. Glial cells and neurons are in a mutual interaction: astrocytes but also microglia control neuronal activity providing trophic factors [118,119], energy [120,121] and regulation of synaptic transmission [122] as well as neurogenesis [123]. Neurons exert an inhibitory control on the immune activity of glial cells [124].…”

Biochemical and Physiological Processes in Brain Function and Drug Actions

“…Glial cells (astrocytes) play a prominent role in recycling and conserving both glutamate and GABA by recapturing them from the synapse, converting them to glutamine, and then returning glutamine to the presynaptic neurons for conversion back to the appropriate transmitter. In addition to the conservation of transmitter, glia protect neurons by limiting synaptic levels of glutamate (Bacci et al 1999;Vardimon et al 1999). Prominent among glutamates several cellular influences is the opening of specific calcium channels that allow the influx of calcium ions into neurons.…”

“…Glial cells guide the synaptic formation of neurons during brain development (Bacci et al 1999), influence the extracellular environment of the neurons (Zahs 1998), synthesize neurotransmitter precursors (Martin 1992), and respond to, or in some cases, may cause brain damage (McGeer and McGeer 1998;Aschner et al 1999;Raivich et al 1999). In turn, neurons are known to produce factors that influence the development and function of glia (Melcangi et al 1999;Vardimon et al 1999).…”

“…Recent investigations have revealed a metabolic coupling between glia and neurons (Poitry-Yamate et al 1995;Tsacopoulos and Magistretti 1996;Bacci et al 1999). Considerable energy is consumed by the various processes of synaptic transmission.…”