Stahl's Essential Psychopharmacology
Neuroscientific Basis and Practical Applications
5th Edition
Author(s)Stephen M. Stahl
TEST BANK
Reference: Ch. 1, Chemical Neurotransmission
Question Stem: A patient is prescribed a medication for
depression that is known to work primarily by blocking the
presynaptic serotonin transporter (SERT). From a
neurobiological perspective, what is the most direct and
immediate consequence of this mechanism in the synaptic
cleft?
Options:
A) Increased synthesis of serotonin from its precursor,
tryptophan.
B) Increased degradation of serotonin by monoamine oxidase
(MAO).
C) Increased concentration and duration of action of serotonin.
D) Downregulation of postsynaptic serotonin receptors.
Correct Answer: C
,Rationales:
• Correct Option C: Blocking the presynaptic SERT inhibits
the reuptake of serotonin from the synaptic cleft back into
the presynaptic neuron. This directly results in a higher
concentration of serotonin remaining in the synapse for a
longer duration, thereby enhancing serotonergic
neurotransmission.
• Incorrect Option A: While SERT blockade may indirectly
influence synthesis through feedback mechanisms, it does
not directly increase the enzymatic conversion of
tryptophan to serotonin.
• Incorrect Option B: SERT blockade does not affect the
activity of monoamine oxidase, the primary enzyme
responsible for serotonin degradation inside the neuron.
• Incorrect Option D: Receptor downregulation is a
secondary, adaptive change that may occur after
prolonged increased neurotransmitter exposure, not an
immediate consequence of transporter blockade.
Teaching Point: SERT blockade increases synaptic serotonin by
preventing its reuptake, a primary mechanism of many
antidepressants.
Citation: Ch. 1, Chemical Neurotransmission
Reference: Ch. 1, Chemical Neurotransmission
,Question Stem: A nursing student is reviewing the mechanism
of benzodiazepines. These drugs act as positive allosteric
modulators at the GABA-A receptor. What is the precise
pharmacodynamic effect of this action?
Options:
A) They directly open the chloride ion channel like GABA does.
B) They bind to the GABA site and prevent GABA from activating
the receptor.
C) They enhance the effect of GABA when it binds, making the
channel open more frequently.
D) They act as enzymes that break down GABA in the synaptic
cleft.
Correct Answer: C
Rationales:
• Correct Option C: Positive allosteric modulators bind to a
site distinct from the neurotransmitter (GABA) binding site.
Their binding changes the receptor's conformation, making
it more likely to open when GABA binds, thereby
enhancing the inhibitory effect of GABA.
• Incorrect Option A: This describes the action of a direct
agonist, not an allosteric modulator.
• Incorrect Option B: This describes the action of a
competitive antagonist.
• Incorrect Option D: Benzodiazepines have no enzymatic
activity; they are receptor ligands.
, Teaching Point: Allosteric modulators alter a receptor's
response to its primary neurotransmitter; they do not activate it
directly.
Citation: Ch. 1, Chemical Neurotransmission
Reference: Ch. 1, Chemical Neurotransmission
Question Stem: When comparing ionotropic and metabotropic
receptors, a key difference is their speed of signal transduction
and duration of action. Which statement accurately describes
this difference?
Options:
A) Metabotropic receptors are faster and shorter-acting
because they directly open ion channels.
B) Ionotropic receptors are faster and shorter-acting because
they directly open ion channels.
C) Both receptor types are equally fast, but metabotropic
effects last longer.
D) Ionotropic receptors are slower but have longer-lasting
effects due to second messenger systems.
Correct Answer: B
Rationales:
• Correct Option B: Ionotropic receptors are ligand-gated ion
channels. Neurotransmitter binding causes an immediate
conformational change that opens the channel, resulting in
Neuroscientific Basis and Practical Applications
5th Edition
Author(s)Stephen M. Stahl
TEST BANK
Reference: Ch. 1, Chemical Neurotransmission
Question Stem: A patient is prescribed a medication for
depression that is known to work primarily by blocking the
presynaptic serotonin transporter (SERT). From a
neurobiological perspective, what is the most direct and
immediate consequence of this mechanism in the synaptic
cleft?
Options:
A) Increased synthesis of serotonin from its precursor,
tryptophan.
B) Increased degradation of serotonin by monoamine oxidase
(MAO).
C) Increased concentration and duration of action of serotonin.
D) Downregulation of postsynaptic serotonin receptors.
Correct Answer: C
,Rationales:
• Correct Option C: Blocking the presynaptic SERT inhibits
the reuptake of serotonin from the synaptic cleft back into
the presynaptic neuron. This directly results in a higher
concentration of serotonin remaining in the synapse for a
longer duration, thereby enhancing serotonergic
neurotransmission.
• Incorrect Option A: While SERT blockade may indirectly
influence synthesis through feedback mechanisms, it does
not directly increase the enzymatic conversion of
tryptophan to serotonin.
• Incorrect Option B: SERT blockade does not affect the
activity of monoamine oxidase, the primary enzyme
responsible for serotonin degradation inside the neuron.
• Incorrect Option D: Receptor downregulation is a
secondary, adaptive change that may occur after
prolonged increased neurotransmitter exposure, not an
immediate consequence of transporter blockade.
Teaching Point: SERT blockade increases synaptic serotonin by
preventing its reuptake, a primary mechanism of many
antidepressants.
Citation: Ch. 1, Chemical Neurotransmission
Reference: Ch. 1, Chemical Neurotransmission
,Question Stem: A nursing student is reviewing the mechanism
of benzodiazepines. These drugs act as positive allosteric
modulators at the GABA-A receptor. What is the precise
pharmacodynamic effect of this action?
Options:
A) They directly open the chloride ion channel like GABA does.
B) They bind to the GABA site and prevent GABA from activating
the receptor.
C) They enhance the effect of GABA when it binds, making the
channel open more frequently.
D) They act as enzymes that break down GABA in the synaptic
cleft.
Correct Answer: C
Rationales:
• Correct Option C: Positive allosteric modulators bind to a
site distinct from the neurotransmitter (GABA) binding site.
Their binding changes the receptor's conformation, making
it more likely to open when GABA binds, thereby
enhancing the inhibitory effect of GABA.
• Incorrect Option A: This describes the action of a direct
agonist, not an allosteric modulator.
• Incorrect Option B: This describes the action of a
competitive antagonist.
• Incorrect Option D: Benzodiazepines have no enzymatic
activity; they are receptor ligands.
, Teaching Point: Allosteric modulators alter a receptor's
response to its primary neurotransmitter; they do not activate it
directly.
Citation: Ch. 1, Chemical Neurotransmission
Reference: Ch. 1, Chemical Neurotransmission
Question Stem: When comparing ionotropic and metabotropic
receptors, a key difference is their speed of signal transduction
and duration of action. Which statement accurately describes
this difference?
Options:
A) Metabotropic receptors are faster and shorter-acting
because they directly open ion channels.
B) Ionotropic receptors are faster and shorter-acting because
they directly open ion channels.
C) Both receptor types are equally fast, but metabotropic
effects last longer.
D) Ionotropic receptors are slower but have longer-lasting
effects due to second messenger systems.
Correct Answer: B
Rationales:
• Correct Option B: Ionotropic receptors are ligand-gated ion
channels. Neurotransmitter binding causes an immediate
conformational change that opens the channel, resulting in
