Serotonin and Depression

Question 1

Describe Serotonin and the place where serotonin neurones are stored in

Answer 1

5-Hydroxytryptamine (5-HT)

regulates important functions such as sleeping, appetite, working memory, mood etc

Stored in the Raphe Nucleus

Question 2

How many receptors there are and the relationship between serotonin receptors and drugs

Answer 2

Many serotonin receptors that regulate different functions
Drugs can interact with one or few serotonin receptors. However, natural compound can interact with all serotonin receptors, which means drugs are more “selective” than natural compounds
the effects of the serotonin to the brain areas depend on which receptor(s) that the serotonin is interacting with

Question 3

Describe the synthesis of serotonin

Answer 3

Tryptophan
(tryptophan hydroxylase)
serotonin
(synthesised by monoamine oxidase)
inactive form of serotonin

Question 4

Describe the relationship between serotonin and depression and tryptophan depletion

Answer 4

Believed that environment and genetic both play a role in depression
however, the dysfunction/disability of serotonin receptors are one of the main reasons that cause depression

PET shows that depression patients have a reduced amount of serotonin receptors (i.e., more “orangy” and colourful brain scans) than normal people

Tryptophan Depletion
a method that aims to create an artificial absence of tyrptophan to create an absence of serotonin, which allows researchers to examine whether serotonin is correlated with depression
works but unethical

Question 5

How does Serotonin antidepressants improve depression and the mystery of SSRI

Answer 5

By blocking the reuptake of serotonin > allowing more serotonin to be binded onto the post-synaptic neurones

Since SSRi is taken orally, the reuptake of serotonin should be blocked in an hour. However, the improvement in mood takes a few weeks to be changed.

The Theories of Long Latency of Onset
The SSRI is changing the neurogenesis (e.g., enzymes and the storage of serotonin neurones) takes time

Question 6

Describe what Prozac does to depression patients and normal people

Answer 6

Patients: reduce symptoms of depression
Normal people: increase empathy and prosocial behaviours

Question 7

Describe the mechanisms of monoamine oxidase and its side effects

Answer 7

Blocks the break down of serotonin into monoamine oxidase
however, lethal if the person takes this medication after consuming much food with tryptophan or tyramine > cheese syndrome
still used as the last alternative and under strict diet control