Name the major excitatory neurotransmitter in the CNS that acts on NMDA and AMPA receptors.

Name the major excitatory neurotransmitter in the CNS that acts on NMDA and AMPA receptors.

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

Answer: (C)

Glutamate is the main excitatory transmitter in the central nervous system, and it binds to several receptor types, including the ionotropic NMDA and AMPA receptors. When released, glutamate activates AMPA receptors to produce a fast depolarizing current through Na+ (and some K+) ions, driving quick excitatory signaling. It also binds NMDA receptors, which require depolarization to remove a Mg2+ block and allow Ca2+ (along with Na+) influx, supporting synaptic plasticity like long-term potentiation. Because these two receptors are primary targets of glutamate and mediate most fast excitatory transmission in the CNS, glutamate is the correct choice. Other listed neurotransmitters have different roles—GABA is inhibitory, norepinephrine modulates arousal and attention, and acetylcholine acts on cholinergic receptors with distinct functions.

Glutamate is the main excitatory transmitter in the central nervous system, and it binds to several receptor types, including the ionotropic NMDA and AMPA receptors. When released, glutamate activates AMPA receptors to produce a fast depolarizing current through Na+ (and some K+) ions, driving quick excitatory signaling. It also binds NMDA receptors, which require depolarization to remove a Mg2+ block and allow Ca2+ (along with Na+) influx, supporting synaptic plasticity like long-term potentiation. Because these two receptors are primary targets of glutamate and mediate most fast excitatory transmission in the CNS, glutamate is the correct choice. Other listed neurotransmitters have different roles—GABA is inhibitory, norepinephrine modulates arousal and attention, and acetylcholine acts on cholinergic receptors with distinct functions.