Neurotransmitter & Receptor Pair	Functions in the CNS
Ionotropic: Ligand-gated ion channels	Transmembrane proteins that allow ions to cross the membrane
Glutamate [E] → NMDA receptor: Ca2+ & Na+ influx	Long-term potentiation of learning & memory
GABA [I] → GABAA receptor: Cl− & HCO3− influx	Sedation, anxiolytic & anticonvulsive
Glycine [I] → Glycine receptor: Cl− influx	Inhibit spinal interneurons (prevents spasticity)
Metabotropic: G protein-coupled receptors	Act through second messengers (eg, cAMP, PKA)
Dopamine → D1-5 receptors	Modulate attention, movement & reward
Serotonin → 5-HT receptors	Modulate mood, nausea & trigeminovascular nociception (migraine)
Norepinephrine → α & β adrenoceptors	Promotes vigilance, attention & emotional memory
Histamine → H3 receptors	Promotes wakefulness

• Acetylcholine
  • Usually excitatory
  • Increased levels
    • Parkinson disease
  • Decreased levels
    • Alzheimer disease, Acetylcholine and Alzheimer’s both start with A
    • Huntington disease
• Dopamine
  • Drive to GET a reward. NOT the feeling of reward. Both excitatory and inhibitory
    • D1 receptor: Subsequent activation of protein kinase A causes smooth muscle relaxation
    • D2 receptor: located mainly in the substantia nigra, striatum, area postrema, and pituitary gland.
    • See dopaminergic pathway
  • Increased levels
    • Schizophrenia
    • Huntington disease
  • Decreased levels
    • Depression
    • Parkinson disease
    • Neuroleptic malignant syndrome (D2 receptor blocked)

Functions of dopamine

D rugs psych O sis P rolactin inhibition A ttention M otivation I nvoluntary movements N ausea E nergy

• Norepinephrine
  • Alertness
  • Increased levels
    • Anxiety
  • Decreased levels
    • Depression
• Serotonin (aka 5-HT)
  • Satiety, Tranquilty, Peace
  • Increased levels
    • Serotonin syndrome
  • Decreased levels
    • Anxiety
    • Depression
    • Parkinson disease
• GABA
  • Inhibitory in the brain
  • Increased levels
  • Decreased levels
    • Anxiety
    • Huntington disease
• Histamine
  • Wakefulness. Think about benadryl (antihistamine) makes us drowsy and sleepy)
• Glutamate
  • Excitatory in the brain, opposite to GABA
    • GlutaMATE
  • Long-term potentiation of learning & memory
  • Glutamate-induced excitotoxicity
• Glycine
  • Inhibitory in the spine