Dopamine and serotonin Flashcards
Where are neurones that produce dopamine found
In the basal ganglia of the brain
What area of the brain is involved in movement
Motor cortex
What can occur at the motor cortex if dopamine is present
Neurones in motor cortex can send signals to rest of the body more easily if dopamine is present
What is dopamine broken down by
MAO enzyme
What is Parkinson’s disease caused when
Neurones that produce dopamine have died so no dopamine is release into the rest of the brain
What does it mean if no dopamine goes to the motor cortex
People with Parkinson’s have trouble moving
What are the symptoms of Parkinson’s
Muscle stiffness, shaking and balance difficulties
What other symptoms can arise due to lack of dopamine
Cognitive and mood disorders
What do treatments for Parkinson’s try to do
replace the effects of lost dopamine
What do MAO inhibitor drugs do
They block MAO from breaking down dopamine
What are the 2 types of MAO drugs
MAO - A inhibitors
MAO - B inhibitors
What do MAO - B inhibitors do
they treat Parkinson’s (MAO B enzymes)
What is also given to increase dopamine
L-DOPA
How does L-DOPA increase dopamine levels
It can be converted into dopamine in the brain
How does gene therapy treat Parkinson’s
it inserts genes that produce proteins that increase the production of dopamine
What is an issue with some Parkinson’s treatments
They often leave patients with too much dopamine
What can too much dopamine cause
Symptoms of schizophrenia
What are people with schizophrenia given to reduce symptoms
Drugs block dopamine receptors, this prevents the post-synaptic membrane from being able to detect dopamine
What can schizophrenic drugs cause
Symptoms of Parkinson’s
Due to the side effects of too much dopamine, what do other treatments for Parkinson’s aim to do
They aim to reduce the symptoms without increasing dopamine
What is an example of a treatment that reduces symptoms of Parkinson’s without increasing dopamine
Dopamine agonists
What do dopamine agonists do
They are molecules that mimic the effects of dopamine on certain dopamine receptors
What is given to sufferers of Parkinson’s who drugs don’t help
Deep brain stimulation
What does DBS involve
An electrode is inserted into the brain in or around the basal ganglia which stimulates the neurones in the same way dopamine normally does
Where are neurones that produce serotonin found
The brainstem but their axons extend to many areas of the brain
How is serotonin distributed
It is released into synapses, then transported back into the pre-synaptic neurone by a serotonin transporter: 5-HTT
What does serotonin influence
Mood
What condition is serotonin linked to
Depression
Describe depression
It is an illness where people are constantly sad for many weeks or months
What are symptoms of depression
Sadness, loss of motivation, loss of hope
How is serotonin linked to depression
people with depression tend to have lower levels of serotonin
Due to the many causes of depression what is it called
A multifactorial condition
What are multifactorial conditions
Conditions caused by a number of factors such as genetics and the environement
How do we know that genetics is linked to depression
If one twin has depression, the other twin is likely to have depression too, The link is more strong in identical twins than non-identical twins
What gene has been linked to depression and why
5-HTT gene as it is involved in reuptake of serotonin
What is the difference between the 2 5-HTT allele’s
The long allele has more base pairs than the short allele
What has been found about the short allele for 5-HTT gene
People with the short allele are more likely to develop depression after a stressful life event
How is serotonin broken down
MAO enzyme
What was an early treatment for depression
MAO inhibitors so serotonin isn’t broken down so its effect lasts longer
What is a modern common treatment for depression
Selective serotonin reuptake inhibitors (SSRI’s)
How do SSRI’s work
They block the re-uptake of serotonin into the pre-synaptic neurone leaving more in the synaptic cleft
What is an issue with SSRI’s
Sometimes helps treat depression but effects are only seen a few weeks after taking it
What does MDMA effect
Mood, memory and perception
Why do people take MDMA
It causes a short term effect of emotional warmth and empathy
What are short term negative effects of MDMA
Hyperthermia (too hot) and kidney failure
What are long term negative effects of MDMA
Depression
What does MDMA effect
Synapses that release serotonin
What do serotonin transporters do
They are in the presynaptic membrane and transport serotonin out of the synaptic cleft and into the presynaptic neurone
What does MDMA do to serotonin transporter’s
It binds to serotonin transporters and blocks them
What is the effect of MDMA binding to serotonin transporters and blocking them
Serotonin remains in the synapse binding to receptors and stimulating the post-synaptic membrane. Causing a positive change in mood
What does overstimulation of the postsynaptic membrane cause
Causes the postsynaptic neurone to lose its sensitivity (desensitised) due to reduced post synaptic serotonin receptors
What does loss in postsynaptic neurone sensitivity cause
Causes post-synaptic neurones to fire less causing a negative change in mood
