Neurotransmitters – Dopamine MCQs With Answer

Neurotransmitters – Dopamine MCQs With Answer

Understanding neurotransmitters—especially dopamine—is essential for B. Pharm students preparing for pharmacology and therapeutics. This concise, exam-focused set covers dopamine biosynthesis, storage, release, receptors (D1–D5), signal transduction, reuptake and metabolism by MAO and COMT, and clinical implications in Parkinson’s disease, schizophrenia, addiction, and endocrine disorders. You will also review dopaminergic pharmacotherapy, including levodopa, dopamine agonists, antipsychotics, MAO-B inhibitors, DAT modulators, and adverse effects. The MCQs emphasize mechanistic detail, receptor pharmacology, drug interactions, and diagnostic approaches relevant to pharmacy practice. Answers reinforce learning and application to patient care. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which enzyme catalyzes the rate-limiting step in dopamine biosynthesis?

• Tyrosine hydroxylase
• L-DOPA decarboxylase
• Monoamine oxidase
• Catechol-O-methyltransferase

Correct Answer: Tyrosine hydroxylase

Q2. The immediate precursor of dopamine in the biosynthetic pathway is:

• Tyrosine
• L-DOPA
• Norepinephrine
• Homovanillic acid

Correct Answer: L-DOPA

Q3. Which cofactor is essential for tyrosine hydroxylase activity?

• Tetrahydrobiopterin (BH4)
• Vitamin B12
• Biotin
• Folate

Correct Answer: Tetrahydrobiopterin (BH4)

Q4. Dopamine is metabolized primarily by which two enzymes?

• MAO and COMT
• Acetylcholinesterase and MAO
• Monoamine oxidase and acetaldehyde dehydrogenase
• COMT and alcohol dehydrogenase

Correct Answer: MAO and COMT

Q5. Which dopamine receptor family is primarily coupled to Gs proteins and increases intracellular cAMP?

• D1-like receptors (D1, D5)
• D2-like receptors (D2, D3, D4)
• NMDA receptors
• Muscarinic receptors

Correct Answer: D1-like receptors (D1, D5)

Q6. The dopamine transporter (DAT) is responsible for:

• Reuptake of dopamine from the synaptic cleft into presynaptic terminals
• Vesicular uptake of dopamine into synaptic vesicles
• Degradation of dopamine in the synapse
• Conversion of dopamine to norepinephrine

Correct Answer: Reuptake of dopamine from the synaptic cleft into presynaptic terminals

Q7. Which drug increases synaptic dopamine by inhibiting vesicular monoamine transporter 2 (VMAT2) causing depletion of vesicular stores?

• Reserpine
• Levodopa
• Bromocriptine
• Selegiline

Correct Answer: Reserpine

Q8. Levodopa is combined with carbidopa in Parkinson’s therapy because carbidopa:

• Inhibits peripheral aromatic L-amino acid decarboxylase, reducing peripheral conversion to dopamine
• Crosses the blood-brain barrier to enhance central dopamine synthesis
• Acts as a dopamine receptor agonist in the striatum
• Inhibits MAO-B centrally

Correct Answer: Inhibits peripheral aromatic L-amino acid decarboxylase, reducing peripheral conversion to dopamine

Q9. Which dopaminergic pathway is most implicated in the positive symptoms of schizophrenia?

• Mesolimbic pathway
• Nigrostriatal pathway
• Tuberoinfundibular pathway
• Mesocortical pathway

Correct Answer: Mesolimbic pathway

Q10. Blockade of D2 receptors in the tuberoinfundibular pathway commonly causes:

• Hyperprolactinemia
• Parkinsonism
• Psychosis exacerbation
• Increased appetite

Correct Answer: Hyperprolactinemia

Q11. Which imaging ligand is commonly used in PET to assess presynaptic dopamine transporter function?

• 11C-raclopride
• 18F-fluorodeoxyglucose
• 123I-FP-CIT (DaTscan)
• 99mTc-HMPAO

Correct Answer: 123I-FP-CIT (DaTscan)

Q12. Selegiline acts in Parkinson’s disease primarily as a:

• Selective MAO-B inhibitor that reduces dopamine breakdown
• COMT inhibitor preventing peripheral L-DOPA metabolism
• Dopamine D2 receptor agonist
• VMAT2 inhibitor

Correct Answer: Selective MAO-B inhibitor that reduces dopamine breakdown

Q13. Which adverse effect is most characteristic of chronic high-dose levodopa therapy?

• Motor fluctuations and dyskinesias
• Hyperprolactinemia
• QT prolongation
• Anticholinergic toxicity

Correct Answer: Motor fluctuations and dyskinesias

Q14. A dopamine agonist commonly used in Parkinson’s disease is:

• Bromocriptine
• Haloperidol
• Reserpine
• Amantadine

Correct Answer: Bromocriptine

Q15. Which statement about D2 receptor signaling is correct?

• D2 receptors are Gi/o-coupled and inhibit adenylate cyclase
• D2 receptors activate adenylate cyclase via Gs
• D2 receptors are ionotropic and allow Na+ influx
• D2 receptors directly phosphorylate tyrosine residues

Correct Answer: D2 receptors are Gi/o-coupled and inhibit adenylate cyclase

Q16. Which metabolite is the main urinary end product of dopamine metabolism?

• Homovanillic acid (HVA)
• Vanillylmandelic acid (VMA)
• 5-Hydroxyindoleacetic acid (5-HIAA)
• Normetanephrine

Correct Answer: Homovanillic acid (HVA)

Q17. Amphetamine increases extracellular dopamine primarily by:

• Reversing DAT and causing dopamine release into the synapse
• Inhibiting MAO-B to reduce dopamine breakdown
• Blocking D2 autoreceptors permanently
• Increasing BH4 synthesis

Correct Answer: Reversing DAT and causing dopamine release into the synapse

Q18. Which antipsychotic has the highest propensity to cause extrapyramidal symptoms due to strong D2 blockade?

• Haloperidol
• Clozapine
• Quetiapine
• Aripiprazole

Correct Answer: Haloperidol

Q19. The nigrostriatal pathway primarily modulates:

• Motor control and coordination
• Endocrine secretion from pituitary
• Cognitive executive functions
• Reward and reinforcement

Correct Answer: Motor control and coordination

Q20. Which drug class is used to inhibit peripheral COMT to prolong levodopa half-life?

• Entacapone and tolcapone (COMT inhibitors)
• MAO inhibitors
• Dopamine agonists
• Muscarinic antagonists

Correct Answer: Entacapone and tolcapone (COMT inhibitors)

Q21. Dopamine’s role in the hypothalamus includes:

• Inhibition of prolactin release via tuberoinfundibular pathway
• Stimulation of growth hormone release directly
• Activation of aldosterone secretion
• Enhancement of insulin secretion from pancreas

Correct Answer: Inhibition of prolactin release via tuberoinfundibular pathway

Q22. Which feature helps distinguish central from peripheral causes of dopamine deficiency on imaging?

• Reduced striatal DAT binding on SPECT or PET indicates presynaptic degeneration (central)
• Elevated urinary HVA indicates peripheral deficiency
• Normal DAT binding with low CSF dopamine indicates central cause
• Increased cardiac sympathetic innervation rules out central causes

Correct Answer: Reduced striatal DAT binding on SPECT or PET indicates presynaptic degeneration (central)

Q23. A partial agonist at D2 receptors used as an antipsychotic is:

• Aripiprazole
• Risperidone
• Haloperidol
• Chlorpromazine

Correct Answer: Aripiprazole

Q24. In Parkinson’s disease, neuronal loss is most pronounced in which structure?

• Substantia nigra pars compacta
• Ventral tegmental area
• Nucleus accumbens
• Locus coeruleus

Correct Answer: Substantia nigra pars compacta

Q25. Which adverse effect is commonly associated with dopamine agonists like bromocriptine and pramipexole?

• Impulse control disorders (e.g., gambling, hypersexuality)
• Severe anticholinergic delirium
• Marked weight loss in all patients
• Profound bradycardia as first-line effect

Correct Answer: Impulse control disorders (e.g., gambling, hypersexuality)

Q26. Which drug reduces dopamine catabolism by inhibiting MAO-B selectively at therapeutic doses?

• Selegiline
• Imipramine
• Propranolol
• Fluoxetine

Correct Answer: Selegiline

Q27. Dopamine D1 receptor activation in the renal system primarily causes:

• Renal vasodilation and natriuresis
• Sodium retention and hypertension
• Glomerular filtration rate decrease
• Antidiuretic hormone release

Correct Answer: Renal vasodilation and natriuresis

Q28. Which test sample is most useful to measure central dopamine turnover clinically or in research?

• Cerebrospinal fluid levels of homovanillic acid (HVA)
• Serum dopamine concentration
• Urinary VMA concentration
• Salivary dopamine levels

Correct Answer: Cerebrospinal fluid levels of homovanillic acid (HVA)

Q29. Which pharmacologic strategy is appropriate for a Parkinson’s patient experiencing wearing-off between levodopa doses?

• Add a COMT inhibitor or increase dosing frequency
• Stop levodopa and start haloperidol
• Introduce an antimuscarinic agent only
• Switch to a selective serotonin reuptake inhibitor

Correct Answer: Add a COMT inhibitor or increase dosing frequency

Q30. Which statement about dopamine and reward pathways is correct?

• Mesolimbic dopamine release reinforces motivated behaviors and drug reward
• Dopamine inhibits all reward processing in the nucleus accumbens
• Mesocortical dopamine exclusively controls motor function
• Tuberoinfundibular pathway mediates reward and reinforcement

Correct Answer: Mesolimbic dopamine release reinforces motivated behaviors and drug reward

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com