Addiction Medicine Certification Neurobiology of Addiction 2 — Questions and Answers
Question 1: How do opioids primarily produce their analgesic and euphoric effects?
- By blocking dopamine reuptake transporters
- By activating mu-opioid receptors coupled to inhibitory G proteins (Correct answer)
- By inhibiting serotonin reuptake
- By potentiating GABA-A receptor activity
Correct answer: By activating mu-opioid receptors coupled to inhibitory G proteins
Opioids bind to mu-opioid receptors (as well as delta and kappa receptors), which are Gi-coupled and reduce neuronal excitability, producing analgesia and euphoria through downstream dopamine release.
Question 2: Alcohol's sedative effects are primarily mediated through which mechanism?
- Increased dopamine release in the striatum
- Potentiation of GABA-A receptors and inhibition of NMDA glutamate receptors (Correct answer)
- Blockade of serotonin 5-HT3 receptors
- Direct activation of mu-opioid receptors
Correct answer: Potentiation of GABA-A receptors and inhibition of NMDA glutamate receptors
Alcohol enhances inhibitory GABAergic neurotransmission at GABA-A receptors and inhibits excitatory glutamatergic neurotransmission at NMDA receptors, producing CNS depression.
Question 3: Why does abrupt alcohol withdrawal cause seizures?
- Excessive dopamine surge in the striatum
- Rebound NMDA receptor hyperactivity and reduced GABA function due to neuroadaptation (Correct answer)
- Rapid opioid receptor downregulation
- Hypoglycemia from impaired hepatic gluconeogenesis
Correct answer: Rebound NMDA receptor hyperactivity and reduced GABA function due to neuroadaptation
Chronic alcohol use upregulates NMDA receptors and downregulates GABA-A receptors; abrupt cessation leaves the brain in a hyperexcitable state due to these neuroadaptations, leading to seizure risk.
Question 4: What is the primary mechanism by which cocaine produces its euphoric effects?
- Activating opioid receptors in the VTA
- Blocking reuptake transporters for dopamine, norepinephrine, and serotonin (Correct answer)
- Potentiating GABA activity in the nucleus accumbens
- Blocking NMDA glutamate receptors
Correct answer: Blocking reuptake transporters for dopamine, norepinephrine, and serotonin
Cocaine blocks monoamine reuptake transporters (DAT, NET, SERT), flooding the synapse with dopamine, norepinephrine, and serotonin, with dopamine accumulation in the nucleus accumbens producing intense euphoria.
Question 5: What role does the prefrontal cortex play in addiction?
- It generates the subjective craving sensation for all substances
- It mediates impulse control and decision-making, both of which are impaired in addiction (Correct answer)
- It produces endogenous opioids that modulate reward
- It controls the autonomic symptoms of withdrawal
Correct answer: It mediates impulse control and decision-making, both of which are impaired in addiction
The prefrontal cortex mediates executive functions including inhibitory control and decision-making; dysfunction of this region in addiction results in impaired control over drug-seeking despite negative consequences.
Question 6: The endocannabinoid system's primary role in addiction neurobiology involves:
- Producing withdrawal symptoms common to all substance use disorders
- Modulating synaptic plasticity and reward processing via CB1 and CB2 receptors (Correct answer)
- Controlling respiratory depression during opioid overdose
- Regulating blood pressure changes during stimulant intoxication
Correct answer: Modulating synaptic plasticity and reward processing via CB1 and CB2 receptors
The endocannabinoid system, through CB1 and CB2 receptors, modulates synaptic plasticity and reward processing and plays a key role in the motivational aspects of multiple substance use disorders.
Question 7: Which neurobiological change is particularly severe and long-lasting in methamphetamine addiction?
- Decreased GABA receptor density in the cortex
- Dopaminergic neurotoxicity with loss of striatal dopamine terminals (Correct answer)
- Permanent mu-opioid receptor upregulation
- Irreversible loss of serotonin synthesis capacity
Correct answer: Dopaminergic neurotoxicity with loss of striatal dopamine terminals
Methamphetamine causes significant dopaminergic neurotoxicity through oxidative stress and excitotoxicity, leading to loss of dopamine nerve terminals in the striatum that can persist for years.
Addiction Medicine Certification Neurobiology of Addiction 2
How do opioids primarily produce their analgesic and euphoric effects?