Lecture 5 Serotonin Flashcards
(28 cards)
What is serotonin synthesized from?
Tryptophan (an amino acid from food) 色氨酸
Where is serotonin released from?
Neurons in the Raphe Nucleus (midline brainstem structure)
What type of neurotransmitter is serotonin?
A neuromodulator (5-HT: 5-Hydroxytryptamine)
What functions is serotonin involved in?
mood, Sleep, arousal, appetite, temperature, working memory, hallucination
Where is all brain serotonin synthesized?
In neurons originating from the Raphe Nucleus
What happens when a serotonin neuron fires?
Stored 5-HT is rapidly released from the synapse
Why do drugs targeting serotonin have different effects?
Due to multiple receptor subtypes
（e.g., 5-HT1A, 5-HT2C, etc.）
What enzymes are involved in serotonin metabolism?
TPH (synthesis)
What are the diagnostic criteria for Major Depression?
At least 5 symptoms in 2 weeks; one must be depressed mood or loss of interest
What is the role of serotonin in depression?
Brain imaging studies show a reduction in some types of serotonin receptors in the brain of unmedicated depressed patients.
What is the genetic link to depression?
A gene related to serotonin transport is linked to higher risk
What is Tryptophan Depletion (TRD)?
A test reducing serotonin synthesis by removing tryptophan → causes depressive symptoms
What increases depression risk after stress?
Impaired serotonin stress response → increased cortisol
How do SSRIs work?
血清素抗抑郁药
Block serotonin reuptake （step 6）→ increase serotonin around synapse → keep firing
Why do SSRIs have delayed effect?
- slow changes in gene expression
- shut off a pathological elevated stress response
- increased level of neurogenesis
Name 3 common SSRIs
Citalopram (Celepram, Clexa) 西酞普兰
Fluoxetine (Prozac, Lovan) 氟西汀
Paroxetine (Paxil, Paxtine) 帕罗西汀
Sertraline (Zoloft) 舍曲林
What is one theory for SSRI long onset time?
Synaptic remodeling or increased neurogenesis over time
What are SSRI effects on personality?
o SSRI’s alter mood and personality.
o In clinical populations: reduces symptoms of Depression
o In healthy people: increases empathy and prosocial behaviour
o Prozac 氟西汀 (Fluoxetine)
- Improved mood
- “Better than well”
- “Feeling like myself for the first time”
- Increased social likeability
How do MAOIs work?
block serotonin breakdown by blocking monoamine oxidase
What is “cheese syndrome”?
Death level of Serotonin from eating tyramine-rich foods while on MAOIs
What does MDMA do to serotonin systems?
o Mimics serotonin, enters presynaptic cells via the SERT transporter.
o Inhibits serotonin packaging into vesicles → serotonin accumulates.
o Reverses SERT, causing massive serotonin release into the synapse.
o Also indirectly affects dopaminergic neurons in the VTA and nucleus accumbens, leading to reward and reinforcement.
o GABAergic neurons attempt to regulate this excitation.
What neurotransmitters does MDMA affect?
Serotonin (5-HT)， dopamine (DA) and noradrenaline (NA)
How does MDMA impact the brain’s reward system?
Indirectly increases dopamine in VTA and nucleus accumbens
Why is MDMA less addictive than cocaine?
It is more serotonergic and less dopaminergic
