3- Neurotransmitter Theories of Schizophrenia Flashcards
What does the dopamine hypothesis explain?
Positive symptoms
How does the dopamine hypothesis explain schizophrenia?
Caused by synapse overactivity between dopaminergic neurons of ventral tegmental area and neurons in mesolimbic pathway (nucleus accumbens and amygdala)
What are dopaminergic neuron activity involved in in these areas?
Reinforcement
What do agonists on dopaminergic neuron synapses do?
Reinforce behaviour
What happens when dopamine agonists are taken in large doses?
They induce positive psychosis symptoms and worsen symptoms in schizophrenia patients
What do antagonists on dopaminergic neuron synapses do?
Work as antipsychotic medication
What 2 effects are produced by dopamine antagonists?
- Reduce positive symptoms
- Side effects caused Parkinson’s-like symptoms
Link to schizophrenia with DA agonist drugs?
Induces/worsens psychotic symptoms
Link to schizophrenia with DA receptor antagonists?
Reduce symptoms
Link to schizophrenia with DA depleting drugs?
Reduce symptoms
Link to schizophrenia with DA metabolites in CSF and plasma?
Increased in schizophrenia
Link to schizophrenia with DA metabolite levels in the brain?
DA increased in striatum
Link to schizophrenia with DA synthesis?
DA increased in striatum
What is the suggestion about the control of striatal dopaminergic activity in schizophrenia?
Too much dopamine activity in the striatum
What is increased dopamine activity associated with?
Schizophrenia positive symptoms
What is the most abundant neurotransmitter in the CNS?
Glutamate
What is glutamate’s effect?
Excitatory
How many synaptic connections is glutamate in?
> 90%
Where does glutamate have a key role?
In learning and memory
What is glutamate involved in?
Synaptic plasticity
What 3 classes of glutamate receptors are there?
- AMPA receptors
- NMDA receptors
- Metabotropic glutamate receptors
What is glutamate’s relevance to schizophrenia?
- Several associated genes code for proteins related to glutamate receptors
- Involved in pathway influencing mesolimbic dopamine activity
- May explain cognitive and negative symptoms
