What is the main inhibitory neurotransmitter in the brain?
GABA
Which enzyme converts glutamate into GABA?
Glutamate decarboxylase (GAD)
Where is GAD found?
Only in GABA-synthesizing neurons
What ion channel is associated with GABAA receptors?
Ligand-gated chloride channel
What type of receptor is GABAB?
G-protein-coupled receptor
What is the mechanism of GABAB inhibition?
GABA activates GPCR → G Protein Inhibits adenylate cyclase → decreases cAMP → reduces Ca2+ channel activation
GABAA receptors share structural similarity with which receptor type?
Nicotinic acetylcholine receptors
How many subunits make up a GABAA receptor?
Five (pentamer)
Which three subunits typically compose GABAA receptors?
α, β, γ
What is the effect of GABAA activation on postsynaptic neurons?
Hyperpolarization due to chloride influx
What is muscimol?
A GABAA receptor agonist with no therapeutic use
What is diazepam’s mechanism at the GABAA receptor?
Binds benzodiazepine site and increases GABA affinity
Pentobarbital affects the GABAA receptor how?
Enhances GABA action through channel modulation
Which GABA-modulating drugs are powerful sedatives?
Barbiturates (e.g., pentobarbital)
Which antagonist blocks the GABAA receptor site?
Bicuculline
Which drug reverses benzodiazepine overdose?
Flumazenil
Which compound blocks the GABAA channel pore?
Picrotoxin
Where is glycine primarily found?
Spinal cord
What ion channel is associated with glycine receptors?
Ligand-gated chloride channel
What is the main glycine receptor antagonist?
Strychnine
What toxin prevents glycine release at inhibitory interneurons?
Tetanus toxin
What condition does tetanus toxin cause?
Excessive reflex hyperexcitability and muscle spasms (‘lockjaw’)
Loss of dopamine neurons is associated with which disease?
Parkinson’s disease
What drug increases dopamine synthesis?
Levodopa (L-DOPA)
