Amino Acids

• Glutamate (glutamic acid) is principal excitatory NT in the brain & spinal cord

  • AMPA, NMDA, kainate & metabotropic receptors
    • PCP acts as an antagonist in the NMDA receptor

• GABA has inhibitory effects

  • Prevents too much firing; linked with epilepsy
  • Benzodiazepines (Valium), barbiturates and steroid binding sites

• Glycine is inhibitory NT in lower brainstem and spinal cord

  • Tetanus (lockjaw) & strychnine

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Some neurons secrete amino acids as NTs

Eg. Glutamate, GABA, Glycine; Glutamate (excitatory effects) & GABA (inhibitory effects) are 2 crucial communicators in the brain

Glutamate interacts with four receptor types:
NMDA receptor: controls a Ca++ (calcium) channel (involved in new memories) PCP, angel dust, though synthetic is associated with the NMDA receptor, acts as indirect antagonist.

AMPA receptor: controls Na+ (sodium) channels (most common glutamate receptor—produces EPSPs)
Kainate receptor: controls Na+ (sodium) channels (also produces EPSPs)
Metabotropic glutamate receptor (another kind of indirect receptor sensitive to glutamate).

GABA—benzodiazepines good anxiety dissolving drugs: help with sleep, relax muscles, reduce seizures; barbiturates sometimes used by vets for anesthetic surgery; progesterone acts on steroid binding site

Strychnine is a highly toxic glycine antagonist; tetanus prevents glycine release