Lecture 19

Question 1

What is the role of GABA and glutamate in the brain?

Answer 1

• Glutamate: Major excitatory neurotransmitter
• GABA: Major inhibitory neurotransmitter
• Together, they maintain the brain’s balance of excitation and inhibition

Question 2

What happens when the brain’s excitation-inhibition balance is disrupted?

Answer 2

• Too much excitation → anxiety, seizures, death
• Too much inhibition → sedation, coma, death

Question 3

What are the main types of glutamate receptors?

Answer 3

• NMDA: Ionotropic (slow voltage-dependent excitation; slow desensitisation)
• AMPA: Ionotropic (rapid excitation; rapid desensitisation)
• Kainate: Ionotropic (rapid excitation; rapid desensitisation)
• mGluR1–7: G-protein coupled (slow excitation)

Question 4

What ions flow through NMDA receptors and what is required for activation?

Answer 4

• Na⁺ and Ca²⁺ influx; K+ efflux
• Requires glutamate orthosteric binding, glycine co-agonist, and depolarisation to remove Mg²⁺ block

Question 5

What are the main types of GABA receptors?

Answer 5

• GABA-A: Ionotropic, heteromeric Cl⁻ channels (fast inhibition)
• GABA-B: Metabotropic G-protein coupled (slow inhibition)
• GABA-C: Ionotropic, homomeric Cl⁻ channels (fast inhibition)

Question 6

What is the effect of GABAA receptor activation?

Answer 6

• Opens Cl⁻ channels → hyperpolarisation → reduced excitability

Question 7

How does ethanol affect GABA-A receptors?

Answer 7

• Positive allosteric modulator
• Increases GABA binding and Cl⁻ influx
• Enhances inhibition (dose-dependent effects on different subunits)

Question 8

How does ethanol affect glutamate receptors?

Answer 8

• Negative allosteric modulator
• Inhibits NMDA receptors (and possibly AMPA)
• Reduces excitation

Question 9

What are the behavioural effects of ethanol?

Answer 9

• Low doses: relaxation, anxiolysis, sedation
• High doses: ataxia, memory loss, anaesthesia, respiratory depression

Question 10

What are the NHMRC alcohol guidelines for adults?

Answer 10

• Max 10 standard drinks/week
• Max 4 standard drinks/day
• Less is safer

Question 11

What is the legal BAC limit for driving in NSW?

Answer 11

• Learners/provisional: 0.00
• Commercial drivers: 0.02
• Fully licensed drivers: <0.05

Question 12

What factors affect BAC?

Answer 12

• Gender, size, weight, liver function, fitness, drinking rate

Question 13

How does ethanol interact with other drugs?

Answer 13

• Alters drug metabolism (↑ or ↓ drug levels)
• Enhances sedative effects (e.g., with benzodiazepines, opioids)
• Dangerous combinations can cause respiratory depression

Question 14

What adaptive changes occur with chronic ethanol use?

Answer 14

• GABAA receptors: downregulated
• NMDA receptors: upregulated
• Leads to tolerance and altered brain excitability

Question 15

What are the symptoms of ethanol withdrawal?

Answer 15

• Insomnia, anxiety, tremors, convulsions
• Treated with benzodiazepines to prevent seizures