2 Minute Neuroscience: Caffeine

Overview

• Caffeine is a stimulant drug
• Most widely-consumed mind-altering substance
• Class: Methylxanthines
• Found in:
  • Coffee seeds
  • Tea leaves

Mechanism of Action

• Adenosine Receptor Antagonist:
  • Caffeine binds to adenosine receptors
  • Blocks adenosine from activating the receptors
  • Reduces activity at adenosine receptors

Receptor Subtypes

• 4 subtypes of adenosine receptor
• Most effects attributed to A1 and A2A subtypes
  • A2A subtype: Promotes wakefulness

Effects on Sleep and Wakefulness

• Adenosine receptors promote sleep regulation
• Adenosine can release GABA (inhibits arousal neurons)
• Caffeine antagonizes adenosine receptors:
  • Opposes sleep-promoting effects
  • Causes arousal

Neurotransmitter Interaction

• Adenosine receptors reduce activity of neurotransmitters:
  • Dopamine
  • Norepinephrine
  • Mechanisms include:
    • Inhibiting neurotransmitter release
    • Affecting neurotransmitter binding
• Caffeine blocks these effects, contributing to its stimulating and reinforcing actions.