What is the primary role of astrocytes in neurotransmitter recycling at synapses?

What is the primary role of astrocytes in neurotransmitter recycling at synapses?

• A. They take up neurotransmitters from the synaptic cleft, help terminate signals, regulate ions, and support metabolic needs.
• B. They generate action potentials to propagate signals.
• C. They form myelin around axons in the CNS.
• D. They release dopamine to modulate mood.

Answer: (A)

Astrocytes play a central role in managing neurotransmitter signaling at synapses by clearing neurotransmitters from the synaptic cleft, helping terminate the signal, and maintaining the ionic environment around the synapse. They take up glutamate and GABA through specific transporters, preventing excessive receptor activation and protecting neurons from excitotoxicity. For glutamate, they convert it to glutamine via glutamine synthetase and shuttle it back to neurons to replenish their transmitter pools—the glutamate-glutamine cycle. This cleanup and recycling, along with ion buffering (especially potassium), are essential for shaping synaptic transmission and supporting neuronal metabolism. They do not generate action potentials, form myelin, or release dopamine as their primary function; those roles belong to other cell types or neuronal processes.

Astrocytes play a central role in managing neurotransmitter signaling at synapses by clearing neurotransmitters from the synaptic cleft, helping terminate the signal, and maintaining the ionic environment around the synapse. They take up glutamate and GABA through specific transporters, preventing excessive receptor activation and protecting neurons from excitotoxicity. For glutamate, they convert it to glutamine via glutamine synthetase and shuttle it back to neurons to replenish their transmitter pools—the glutamate-glutamine cycle. This cleanup and recycling, along with ion buffering (especially potassium), are essential for shaping synaptic transmission and supporting neuronal metabolism. They do not generate action potentials, form myelin, or release dopamine as their primary function; those roles belong to other cell types or neuronal processes.