Stahl's Essential Psychopharmacology
Neuroscientific Basis and Practical Applications
5th Edition
Author(s)Stephen M. Stahl
TEST BANK
1
Reference: Ch. 1, Principles of Chemical Neurotransmission
Question Stem: A patient treated with a new psychotropic drug
develops rapid tolerance to its behavioral effects. Which
synaptic mechanism best explains this clinical tolerance?
A. Increased neurotransmitter synthesis in the presynaptic
neuron
B. Postsynaptic receptor internalization (down-regulation)
following prolonged agonist exposure
C. Permanent loss of presynaptic axon terminals
D. Enhanced action potential propagation along the axon
Correct Answer: B
Rationales:
• B (Correct): Prolonged agonist exposure often triggers
receptor phosphorylation and internalization (down-
regulation), reducing postsynaptic responsiveness and
, producing tolerance. Stahl emphasizes receptor trafficking
as a key mechanism of pharmacologic tolerance.
Cambridge University Press & Assessment
• A: Increased synthesis could sustain signaling, not produce
tolerance; it’s not the primary mechanism of rapid
receptor-level tolerance.
• C: Permanent loss of terminals (neurodegeneration) is not
the typical reversible mechanism underlying
pharmacologic tolerance.
• D: Enhanced action potential conduction would increase,
not reduce, synaptic signaling and does not explain
tolerance.
Teaching Point: Receptor internalization reduces postsynaptic
responsiveness and causes tolerance.
Citation: Ch. 1, Chemical Neurotransmission. Stahl, 5th ed.
Cambridge University Press & Assessment
2
Reference: Ch. 1, Synaptic Vesicle Release & Exocytosis
Question Stem: A clinician considers a medication that blocks
presynaptic voltage-gated calcium channels. Which immediate
effect at the synapse would be expected?
A. Increased neurotransmitter vesicle fusion
B. Decreased neurotransmitter release into the synaptic cleft
C. Increased postsynaptic receptor expression
,D. Enhanced synthesis of neurotransmitter precursors
Correct Answer: B
Rationales:
• B (Correct): Calcium influx through presynaptic voltage-
gated calcium channels is required for synaptic vesicle
fusion; blocking these channels reduces neurotransmitter
release. Stahl explains Ca²⁺-triggered exocytosis as
essential for transmitter release. Cambridge University
Press & Assessment
• A: Blocking calcium channels reduces, not increases,
vesicle fusion.
• C: Postsynaptic receptor expression is regulated over
longer timescales and is not an immediate consequence of
presynaptic calcium channel blockade.
• D: Synthesis of precursors is intracellular and not directly
increased by blocking presynaptic Ca²⁺ entry.
Teaching Point: Presynaptic Ca²⁺ influx is the trigger for
neurotransmitter exocytosis.
Citation: Ch. 1, Chemical Neurotransmission. Stahl, 5th ed.
Cambridge University Press & Assessment
3
Reference: Ch. 1, Neurotransmitter Receptors: Ionotropic vs
Metabotropic
, Question Stem: A patient needs rapid symptomatic relief of
agitation. Which receptor target is most likely to produce the
fastest change in postsynaptic neuronal excitability?
A. G-protein-coupled receptor that activates adenylate cyclase
B. Nuclear receptor regulating gene transcription
C. Ligand-gated (ionotropic) receptor that opens a chloride
channel
D. Enzyme inhibitor that modulates second-messenger
synthesis slowly
Correct Answer: C
Rationales:
• C (Correct): Ionotropic receptors (ligand-gated ion
channels) produce rapid changes in membrane potential
by directly opening ion channels — delivering fast
symptomatic effects. Stahl contrasts fast ionotropic
signaling with slower metabotropic pathways. Cambridge
University Press & Assessment
• A: GPCR-mediated signaling is slower because it relies on
G-protein and second-messenger cascades.
• B: Nuclear receptors act over hours to days via
transcriptional changes, not immediate relief.
• D: Enzyme inhibitors affecting second messengers typically
act more slowly than direct ion channel modulation.
Teaching Point: Ionotropic receptors mediate the fastest
synaptic effects via direct ion flow.
Neuroscientific Basis and Practical Applications
5th Edition
Author(s)Stephen M. Stahl
TEST BANK
1
Reference: Ch. 1, Principles of Chemical Neurotransmission
Question Stem: A patient treated with a new psychotropic drug
develops rapid tolerance to its behavioral effects. Which
synaptic mechanism best explains this clinical tolerance?
A. Increased neurotransmitter synthesis in the presynaptic
neuron
B. Postsynaptic receptor internalization (down-regulation)
following prolonged agonist exposure
C. Permanent loss of presynaptic axon terminals
D. Enhanced action potential propagation along the axon
Correct Answer: B
Rationales:
• B (Correct): Prolonged agonist exposure often triggers
receptor phosphorylation and internalization (down-
regulation), reducing postsynaptic responsiveness and
, producing tolerance. Stahl emphasizes receptor trafficking
as a key mechanism of pharmacologic tolerance.
Cambridge University Press & Assessment
• A: Increased synthesis could sustain signaling, not produce
tolerance; it’s not the primary mechanism of rapid
receptor-level tolerance.
• C: Permanent loss of terminals (neurodegeneration) is not
the typical reversible mechanism underlying
pharmacologic tolerance.
• D: Enhanced action potential conduction would increase,
not reduce, synaptic signaling and does not explain
tolerance.
Teaching Point: Receptor internalization reduces postsynaptic
responsiveness and causes tolerance.
Citation: Ch. 1, Chemical Neurotransmission. Stahl, 5th ed.
Cambridge University Press & Assessment
2
Reference: Ch. 1, Synaptic Vesicle Release & Exocytosis
Question Stem: A clinician considers a medication that blocks
presynaptic voltage-gated calcium channels. Which immediate
effect at the synapse would be expected?
A. Increased neurotransmitter vesicle fusion
B. Decreased neurotransmitter release into the synaptic cleft
C. Increased postsynaptic receptor expression
,D. Enhanced synthesis of neurotransmitter precursors
Correct Answer: B
Rationales:
• B (Correct): Calcium influx through presynaptic voltage-
gated calcium channels is required for synaptic vesicle
fusion; blocking these channels reduces neurotransmitter
release. Stahl explains Ca²⁺-triggered exocytosis as
essential for transmitter release. Cambridge University
Press & Assessment
• A: Blocking calcium channels reduces, not increases,
vesicle fusion.
• C: Postsynaptic receptor expression is regulated over
longer timescales and is not an immediate consequence of
presynaptic calcium channel blockade.
• D: Synthesis of precursors is intracellular and not directly
increased by blocking presynaptic Ca²⁺ entry.
Teaching Point: Presynaptic Ca²⁺ influx is the trigger for
neurotransmitter exocytosis.
Citation: Ch. 1, Chemical Neurotransmission. Stahl, 5th ed.
Cambridge University Press & Assessment
3
Reference: Ch. 1, Neurotransmitter Receptors: Ionotropic vs
Metabotropic
, Question Stem: A patient needs rapid symptomatic relief of
agitation. Which receptor target is most likely to produce the
fastest change in postsynaptic neuronal excitability?
A. G-protein-coupled receptor that activates adenylate cyclase
B. Nuclear receptor regulating gene transcription
C. Ligand-gated (ionotropic) receptor that opens a chloride
channel
D. Enzyme inhibitor that modulates second-messenger
synthesis slowly
Correct Answer: C
Rationales:
• C (Correct): Ionotropic receptors (ligand-gated ion
channels) produce rapid changes in membrane potential
by directly opening ion channels — delivering fast
symptomatic effects. Stahl contrasts fast ionotropic
signaling with slower metabotropic pathways. Cambridge
University Press & Assessment
• A: GPCR-mediated signaling is slower because it relies on
G-protein and second-messenger cascades.
• B: Nuclear receptors act over hours to days via
transcriptional changes, not immediate relief.
• D: Enzyme inhibitors affecting second messengers typically
act more slowly than direct ion channel modulation.
Teaching Point: Ionotropic receptors mediate the fastest
synaptic effects via direct ion flow.
