Astrocytes and the BBB

Vocabulary-focused flashcards covering key astrocyte functions, the tripartite synapse, the blood–brain barrier, and glial scar dynamics as presented in the lecture notes.

Astrocyte

A star-shaped glial cell that defines and connects domains of neurons, synapses, and blood vessels; communicates via gap junctions; participates in the blood–brain barrier (BBB) and modulates synaptic activity through gliotransmitters.

Tripartite synapse

A synapse formed by the presynaptic terminal, the postsynaptic neuron, and an encasing astrocyte that modulates transmission via gliotransmitters.

Blood–brain barrier (BBB)

Selective barrier between intracerebral blood vessels and brain parenchyma formed by tight junctions of endothelial cells and astrocyte endfeet; regulates solute movement.

Endfeet

Specialized astrocyte processes that ensheath brain blood vessels at the BBB and host transporters (e.g., GLUT1, Kir4.1, AQP4).

Tight junctions

Protein complexes between endothelial cells that create a seal, preventing paracellular diffusion and contributing to BBB integrity.

Circumventricular organs (CVOs)

Brain regions lacking a complete BBB, enabling neuroendocrine signaling; present in areas like the neurohypophysis and pineal gland.

Glial scar

Reactive, fibrotic astrocyte response after CNS injury forming a barrier that can inhibit or modulate axon regeneration and inflammation.

Bergmann glia

Astrocyte-like cells in the cerebellum that interact with Purkinje cells and can enwrap thousands of synaptic contacts.

Purkinje cells

Large cerebellar neurons whose synapses interact with Bergmann glia; involvement illustrated by astrocyte wrapping.

Glutamate clearance

Astrocytes remove synaptic glutamate from the cleft and convert it to glutamine for neuronal reuse.

Glutamine (Gln) supply

Astrocyte-derived glutamine provided to neurons as a substrate for glutamate synthesis.

NMDA receptor

Glutamate receptor subtype critical for calcium entry and synaptic plasticity; target for glutamatergic signaling in tripartite synapses.

AMPA receptor

Fast-acting ionotropic glutamate receptor mediating major excitatory postsynaptic currents.

Kainate receptor

Glutamate receptor type contributing to excitatory neurotransmission at synapses.

mGluR (metabotropic glutamate receptor)

G-protein–coupled glutamate receptor that modulates neuronal excitability and synaptic transmission.

ATP (gliotransmitter)

A gliotransmitter released by astrocytes that modulates synaptic transmission via receptors and can influence AMPA receptor trafficking and calcium signaling.

P2X receptor

ATP-gated ion channel involved in astrocyte-neuron communication and synaptic modulation.

P2Y receptor

G-protein coupled receptor activated by ATP/ADP; participates in gliotransmission and calcium signaling.

A1 receptor

Adenosine A1 receptor mediating inhibitory modulation in synaptic transmission influenced by astrocyte signaling.

SNARE proteins

Proteins that mediate vesicle fusion and exocytosis, enabling gliotransmitter release from astrocytes.

Calcium signaling in astrocytes

Astrocytes show intracellular Ca2+ transients in response to neuronal activity, driving gliotransmitter release via ER Ca2+ stores.

Long-term potentiation (LTP)

Persistent enhancement of synaptic strength; astrocyte signaling and gliotransmission can influence LTP induction and maintenance.

GLUT1

Glucose transporter expressed at the BBB endothelium, supplying glucose to the brain.

Kir4.1

Inward-rectifier potassium channel in astrocyte endfeet involved in K+ buffering and homeostasis.

Aquaporin-4 (AQP4)

Water channel in astrocyte endfeet implicated in water homeostasis across the BBB.

Chondroitin sulfate proteoglycan (CSPG)

Extracellular matrix molecules enriched in the glial scar that can inhibit neurite outgrowth.

Netrins

Guidance cues present in the glial scar environment that influence neurite extension and pathfinding.

Tenascin

ECM protein associated with the glial scar; modulates cell adhesion and neurite behavior.

Laminin

Basement membrane ECM protein that influences cell adhesion and neurite outgrowth within the CNS.

NGF (nerve growth factor)

Neurotrophic factor involved in survival and growth of neurons; part of scar signaling milieu.

BDNF (brain-derived neurotrophic factor)

Neurotrophin supporting neuron survival, growth, and synaptic plasticity; mentioned in growth-factor contexts for regeneration.

CNTF receptor

Receptor for ciliary neurotrophic factor involved in glial signaling and scar-related pathways.

PTEN

Tumor suppressor gene; its deletion enhances axon regeneration via the PI3K–Akt–mTOR pathway.

mTOR

Central kinase regulating cell growth and regeneration; activated downstream of PTEN loss to promote axon growth.

Beclin-1

Autophagy-related protein involved in cellular turnover and regeneration pathways.

NT3

Neurotrophin-3; growth factor used to promote neuronal survival and regeneration.

Growth-factor hydrogel (growth factor depot)

Biomaterial delivery system (e.g., hydrogel) delivering NT3 and BDNF to promote axon regeneration after injury.

AAV-Cre

Adeno-associated virus delivering Cre recombinase for conditional gene knockout studies.

AAV-GFP

Adeno-associated virus delivering GFP as a control or reporter in gene delivery experiments.