From the Guidelines
Glial cells, including astrocytes and microglia, play a crucial role in maintaining the blood-brain barrier, regulating immune responses, and promoting inflammation in the neurovascular unit. According to a study published in the journal Stroke in 2006 1, these cells contribute to the development and maintenance of tight junction proteins and participate in an immune response when challenged by injury or infection. The study highlights the importance of glial cells in regulating blood-brain barrier permeability and initiating an immune response by releasing cyto-active factors that promote inflammation.
Some key functions of glial cells include:
- Maintaining homeostasis by regulating ion concentrations and pH levels in the neural environment
- Providing physical and metabolic support to neurons by supplying nutrients and removing waste products
- Forming myelin sheaths around axons to enable rapid signal transmission
- Responding to injury and infection as part of the immune defense within the nervous system
- Guiding neuronal development and migration during brain formation
- Participating in synaptic function by regulating neurotransmitter levels
The study also notes that abatement of inflammation in the brain depends on receptor-specific signaling, the production of anti-inflammatory agents, or the presence of global factors that alter the set point for inflammation, with anti-inflammatory cytokines such as interleukin (IL)-10, IL-4, and IL-13 playing a crucial role 1. Overall, glial cells are essential for normal brain function and may be potential therapeutic targets for neurological disorders.
From the Research
Role of Glial Cells in the Central Nervous System
- Glial cells, including astrocytes, oligodendrocyte lineage cells, and microglia, account for more than 50% of the total number of cells in the mammalian brain and play key roles in modulating various brain activities under physiological and pathological conditions 2.
- These cells can form highly complex interconnections with each other, with the astroglial network being well described, and oligodendrocytes and microglia also contributing to the formation of glial networks under various circumstances 2.
Glial Cells as Barriers and Signaling Intermediaries
- Glial cells provide metabolic support to neurons by isolating distinct neuronal compartments from systemic signals and selectively transporting specific metabolites and ions to support neuronal development and facilitate neuronal function 3.
- They occupy privileged positions within the nervous system and have evolved to serve as signaling intermediaries in various contexts, regulating nervous system development, function, and response to injury 3.
Immune Response and Ischemic Stroke
- Glial cells, including microglia, astrocytes, and oligodendrocytes, are implicated in post-stroke immune regulation and exert both beneficial and detrimental effects during ischemic stroke 4.
- Microglia are rapidly activated after ischemic stroke, releasing inflammatory cytokines that induce neuronal tissue injury, while alternatively activated microglia secrete anti-inflammatory cytokines and neurotrophic factors that are beneficial for recovery 4.
Vascular Function and Glial Cells
- Glial cells play a crucial role in the vascular function of the central nervous system, with astrocytes, microglia, and oligodendrocytes surrounding brain vessels and regulating the activity of vascular endothelial growth factor (VEGF) or Wnt-dependent endothelial angiogenesis mechanism 5.
- The interaction between glial cells and vascular function is essential for the permeability and integrity of the blood-brain barrier (BBB) and for monitoring cerebral blood flow via Ca2+/K+-dependent pathways 5.
Glial Cells in Central Nervous System Formation and Function
- Glial cells orchestrate essentially all aspects of nervous system formation and function, from neuronal birth, migration, axon specification, and growth through circuit assembly and synaptogenesis 6.
- Distinct glia fulfill key roles in synaptic communication, plasticity, homeostasis, and network-level activity through dynamic monitoring and alteration of CNS structure and function 6.