Question 1

Which enzyme catalyzes the rate-limiting step in serotonin synthesis in animals, and what is the reaction it catalyzes?

Accepted Answer

Tryptophan hydroxylase; converts tryptophan to 5-hydroxytryptophan ($$	ext{Tryptophan} \xrightarrow{	ext{Tryptophan Hydroxylase}} 	ext{5-HTP})$$

Question 2

A mouse model with a de novo mutation shows impaired central serotonin synthesis but normal peripheral serotonin levels. Which gene is most likely mutated?

Accepted Answer

TPH2

Question 3

Which drug blocks the transport of serotonin into synaptic vesicles, and what is the transporter involved?

Accepted Answer

Reserpine; VMAT2

Question 4

Serotonin is removed from the synaptic cleft primarily by which mechanism, and which drug class targets this process to treat depression?

Accepted Answer

Reuptake by SERT; SSRIs

Question 5

Individuals with the S-S genotype of the SERT gene are most vulnerable to which condition following stressful life events?

Accepted Answer

Depressive episodes

Question 6

Which amphetamine is used experimentally to increase serotonin release, and which is used for appetite suppression?

Accepted Answer

Para-chloroamphetamine; fenfluramine

Question 7

MDMA is known to cause neurotoxicity in serotonergic neurons. What is the primary detrimental effect of MDMA on cortical neurons?

Accepted Answer

It is toxic to serotonergic neurons, causing long-term depletion of serotonin

Question 8

Which metabolite is produced after monoamine oxidase (MAO) degrades serotonin?

Accepted Answer

5-HIAA

Question 9

True or false: All serotonin receptors are exclusively ionotropic.

Accepted Answer

False

Question 10

Which of the following best describes the mechanism of 5-HT1A receptor activation?

Accepted Answer

Inhibits adenylyl cyclase, increases potassium channel opening

Question 11

Which brain region has the highest concentration of 5-HT1A receptors?

Accepted Answer

Prefrontal cortex

Question 12

Stimulation of 5-HT1A receptors leads to which effect on cAMP synthesis?

Accepted Answer

Reduced cAMP synthesis

Question 13

Which of the following is a 5-HT1A receptor antagonist?

Accepted Answer

WAY 100635

Question 14

Genetic deletion of the 5-HT1A receptor in mice leads to which behavioral phenotype?

Accepted Answer

Induced anxiety-like behavior

Question 15

Where are 5-HT2A receptors primarily located, and what is their main signaling pathway?

Accepted Answer

Cerebral cortex; activates phosphoinositide pathway and increases $$Ca^{2+} in $$postsynaptic cells

Question 16

Which drug acts as a hallucinogenic 5-HT2A agonist?

Accepted Answer

DOI

Question 17

What is the most common pharmacotherapy for anxiety disorders, and which serotonin receptor is primarily involved?

Accepted Answer

SSRIs; 5-HT1A

Question 18

Knockout mice lacking 5-HT1A receptors in the forebrain during early postnatal development show which outcome?

Accepted Answer

Altered neural circuitry and increased expression of anxiety in adulthood

Question 19

Which two major physiological defects are observed in mice lacking serotonergic neurons?

Accepted Answer

Problems with thermoregulation; long-lasting episodes of apnea

Question 20

Stimulation of which serotonergic receptor subtype is associated with reduced food intake (hypophagia)?

Accepted Answer

5-HT1A

Serotonin: Synthesis, Transport, Receptors, and Clinical Relevance

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