Serotonin

Serotonin is synthesized from ___________

Tryptophan

Tryptophan is obtained from _________

diet protein

Gut —> Tryptophan —> _____ (via TPH2) —> 5-HT (via ______)

5-HTP, AADC

What is used as a serotonergic neuron marker?

TPH2

What is the rate limiting step in serotonin synthesis?

TPH2

What prevents tryptophan from passing through the BBB into the brain?

Large amino acid competitors

How can 5-HTP aid in tryptophan passing through the BBB into the brain?

5-HTP does not have to go through TPH2 which is rate limiting

90% of tryptophan is converted to __________ pathway during stress.

kynurenine

How is kynurenine synthesized?

Tryptophan —> Stress stimulates IDO —> kynurenine

What can 5-HT be converted into which explains the connection of sleepiness?

Melatonin

What is a commonality between catecholamine and serotonin synthesis?

AADC

AADC converts _____ and _____ to serotonin and dopamine.

5-HTP, DOPA

Why is dopamine not created with AADC conversion in serotonin synthesis?

DOPA is not the precursor in serotonin synthesis, 5-HTP is

What neurotransmitters do VMAT2 package into vesicles?

Serotonin, dopamine, and norepinephrine

Serotonin _________ is stimulated from drugs like MDMA (“ecstasy”)

release

Serotonin release can be inhibited by which two things?

1. Autoreceptors (negative feedback loop)

2. Dendrite autoreceptor activation

What is SERT responsible for?

Reuptake of 5-HT

What is MAO responsible for?

Metabolizing serotonin

What would happen to serotonin levels if we agonized autoreceptors?

Decrease serotonin and increase negative feedback loop

What would happen to serotonin levels if we antagonized autoreceptors?

Increase serotonin and decrease negative feedback loop

What would happen to serotonin levels if we agonized SERT?

Decrease serotonin and increase reuptake

What would happen to serotonin levels if we antagonized SERT?

Increase serotonin and decrease reuptake

______ increases serotonin

MDMA

What are the 3 ways MDMA increases serotonin levels?

1. Interfering with VMAT2 packaging of serotonin into vesicles

2. Antagonism of SERT

3. Agonism of 5-HT receptors

Serotonergic neurons are found in _______ nuclei

raphe

90-95% of serotonin in the body is found in the _____

gut

Serotonin receptors are ___________

metabotropic

There are _________ of serotonin receptor.

more than one type

What happens when serotonin binds with a receptor?

Hyperpolarization with K+ efflux and effects on gene expression

Increase aggression, increase impulsivity, increase compulsivity, and decrease social behaviors are all effects of _______ serotonin.

decreasing

Decreasing anxiety is an effect of ________ serotonin.

increasing

Decrease in ____ in knockout mice caused increased aggression.

TPH2

Increase in _____ caused decreased anxiety and more time in _______ over cliff in mice.

5-HT, open-arm