Glialsignaler

Glialsignaler is a term used in neuroscience to describe the signal-transduction roles of glial cells in modulating neural activity and circuit function. Glial cells, including astrocytes, oligodendrocyte lineage cells, microglia, Schwann cells, and satellite glia, participate in intercellular communication and homeostasis across both the central and peripheral nervous systems, even though they do not fire action potentials like neurons.

Glial signaling occurs through several mechanisms. Astrocytes exhibit intracellular calcium elevations that can trigger the release of gliotransmitters such as glutamate, D-serine, and ATP, influencing nearby synapses in what is described as the tripartite synapse. Purinergic signaling involves ATP and its breakdown product adenosine, which modulate neuronal excitability and synaptic strength. Gap junction networks formed by connexins enable direct glial-glial and glial-neuronal communication, while extracellular vesicles and cytokines from glia convey signals related to metabolism, inflammation, and repair. Microglia respond to injury or disease with immune signaling, including cytokines and chemokines, that can affect synapses and neuronal function.

Glial signaling serves diverse roles in nervous system function. It helps regulate synaptic transmission and plasticity, maintains ion and metabolite balance, and participates in cerebral blood flow and the blood-brain barrier. Glial signaling contributes to sleep regulation, pain processing, and responses to injury or disease, and microglial activity is involved in synaptic pruning during development and in neurodegenerative contexts.

Research in glial signaling employs calcium imaging, optogenetics, chemogenetics, and electrophysiological approaches to dissect glial-neuronal interactions. While evidence supports meaningful glial contributions to neural computation, questions remain about the extent, context, and physiological relevance of gliotransmission, and about the heterogeneity of glial signaling across brain regions and species.