Astrocytes
Astrocytes
- Alexei VerkhratskyAlexei VerkhratskyUniversity of Manchester
Summary
Astrocytes belong to an extended class of astroglia, a class of neural cells of ectodermal, neuroepithelial origin that sustain homeostasis and provide for defense of the brain and the spinal cord. Astroglial cells support homeostasis of the central nervous system at all levels of organization from molecular to organ-wide. Astrocytes cannot generate action potentials, being thus electrically nonexcitable cells. Astrocytic excitability is intracellular, being mediated by associations with spatiotemporal fluctuations of cytoplasmic ions and second messengers in response to chemical or mechanical stimulation. Astrocytes express an extended complement of receptors to neurotransmitters and neurohormones that allow them to coordinate their homeostatic function with neuronal activity. Astrocytic homeostatic responses are primarily mediated by plasmalemmal transporters, which in turn are regulated by cytoplasmic concentration of Na+ ions. Peripheral astrocytic processes, known as leaflets, establish intimate contacts with synapses forming an astroglial synaptic cradle. Astrocytes regulate synaptogenesis, synaptic isolation, synaptic maintenance, and synaptic extinction, thus being fundamental for neuronal plasticity. Loss of astrocytic homeostatic function leads to neuronal damage and is a universal part of pathogenesis of many neurological diseases.
Keywords
Subjects
- Molecular and Cellular Systems