What is the main excitatory neurotransmitter in the CNS?

What is the main excitatory neurotransmitter in the CNS?

• A. GABA
• B. Glutamate
• C. Glycine
• D. Acetylcholine

Answer: (B)

Glutamate is the principal excitatory neurotransmitter in the CNS. When it is released, it binds to ionotropic receptors such as AMPA, NMDA, and kainate on the postsynaptic neuron, opening cation channels and producing an excitatory postsynaptic potential by allowing positive ions (primarily Na+, and Ca2+ at NMDA receptors) to enter. This fast depolarization drives most excitatory signaling in brain circuits and underlies synaptic plasticity processes like long-term potentiation, which are crucial for learning and memory. GABA, in contrast, is the main inhibitory transmitter, dampening neuronal activity by promoting Cl− influx through GABA_A receptors or activating K+ channels via GABA_B receptors. Glycine is another inhibitory transmitter, mainly in the spinal cord and brainstem. Acetylcholine has important roles in both CNS and PNS, including excitatory actions at nicotinic receptors, but it is not the predominant excitatory transmitter in the CNS overall.

Glutamate is the principal excitatory neurotransmitter in the CNS. When it is released, it binds to ionotropic receptors such as AMPA, NMDA, and kainate on the postsynaptic neuron, opening cation channels and producing an excitatory postsynaptic potential by allowing positive ions (primarily Na+, and Ca2+ at NMDA receptors) to enter. This fast depolarization drives most excitatory signaling in brain circuits and underlies synaptic plasticity processes like long-term potentiation, which are crucial for learning and memory.

GABA, in contrast, is the main inhibitory transmitter, dampening neuronal activity by promoting Cl− influx through GABA_A receptors or activating K+ channels via GABA_B receptors. Glycine is another inhibitory transmitter, mainly in the spinal cord and brainstem. Acetylcholine has important roles in both CNS and PNS, including excitatory actions at nicotinic receptors, but it is not the predominant excitatory transmitter in the CNS overall.