MCQ – 79741

Correct Answer » C Explanation

• Glutamate is the major excitatory (facilitatory) neurotransmitter in the central nervous system.
• It facilitates synaptic transmission by depolarizing the postsynaptic membrane through activation of:
  • N-Methyl-D-Aspartate (NMDA) receptors
  • α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors
  • Kainate receptors
• It plays a crucial role in:
  • Learning
  • Memory
  • Synaptic plasticity
  • Long-term potentiation (LTP)

Why Other Options are Incorrect

A. Gamma-aminobutyric acid (GABA)

• Major inhibitory neurotransmitter in the brain.
• Produces neuronal inhibition by increasing chloride ion influx through GABA-A receptors.
• Does not facilitate presynaptic transmission.

B. Glycine

• Major inhibitory neurotransmitter in the spinal cord and brainstem.
• Increases chloride ion conductance, causing neuronal hyperpolarization.
• Not a facilitatory neurotransmitter.

D. Aspartate

• Aspartate is an excitatory amino acid neurotransmitter.
• However, its physiological role is much less significant than glutamate.
• Glutamate is the principal facilitatory neurotransmitter in the CNS.