Week 8 Flashcards
Glutamate
– ThedominantexcitatoryCNSneurotransmitter
– Binds/opensiGluRs(ionotropicglutamatereceptors)
• AMPA receptor is a Na+ channel (EPSP)
• NMDA receptor is a Na+ and Ca2+ channel (EPSP)
– AlsomGluRs(metabotropicglutamatereceptors)
GABA
– ThedominantinhibitoryCNSneurotransmitter
– Binds/opens GABAARs: Cl- channels
• Cl- influx causing hyperpolarisation
• Inhibits post-synaptic neuron (IPSP)
– AlsoGABABRs(metabotropic)
Acetylcholine (ACh) - excitatory or inhibitory
– Nicotinic (nAChR)
• Ionotropic - ligand-gated Na+ channel • Always excitatory
– Muscarinic (mAChR) - GPCRs
• Metabotropic - activates enzymes • Often inhibitory (can be excitatory)
Nordrenaline (NA) - excitatory or inhibitory
– Alpha-adrenergic receptors - GPCRs
• Metabotropic - activates enzymes • Excitatory of inhibitory
– Beta-adrenergic receptors - GPCRs
• Metabotropic - activates enzymes
• Excitatory or inhibitory
Normal cognition
- ‘Normal’ thinking depends on the balance of excitatory Glutamate & inhibitory GABA → = impaired cognition
- Behaviour and emotions are even more complicated
Dopamine (DA) - ON
• ON = activate DA Receptors (GPCRs)
– D1-like (↑cAMP) and D2-like (↓cAMP) are all GPCRs but act in contradictory ways
Dopamine (DA) - OFF
– Reuptake - DA transporter (DAT), then…
– broken down by enzymes: monoamine oxidase (MAO), catechol-O-methyl transferase (COMT)
Serotonin or 5-hydroxytriptamine (5-HT) - ON
• ON = activate 5-HT Receptors
– The 5-HT receptors, are GPCRs → signalling
• (except 5-HT3 receptor = ligand-gated cation channel)
Serotonin or 5-hydroxytriptamine - OFF
• OFF = reuptake
– monoamine transporter (SERT), on the presynaptic neuron.
– Various agents can inhibit 5-HT reuptake, including cocaine, tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs) → increase synaptic 5-HT