schizophrenia Flashcards
Four main NT involved in Schizo
Dopamine
Serotonin
Glutamate
GABA
Schizophrenia: decreased dopamine in which region? (hypofrontality)
PFC
Schizophrenia: increased dopamine in which region?
Nucleus Accumbens (D2 receptors)
in schizophrenia decreased DA in the PFC is responsible for
cognitive deficits / negative symptoms
in schizophrenia increased DA in the NA is responsible for
positive symptoms
mesolimbic dopamine
dopamine in NA = increased in schiz
what system is abnormal in schizophrenia
mesocorticolimbic dopamine system
enhanced neurotransmission at what receptors produces positive symptoms of schizo?
D2 receptors pre and post synaptically
First Generation Neuroleptics
phenothiazines, thioxanthines, antiemetics, butyrophenones, diphenylbutylpiperidines
First Generation Neuroleptics Method of Action
ANTAGONISE DA RECEPTORS
(block d1 and d2 receptors)
Benefit of butyrophenones & diphenylbutylpiperidines compared to other first gen antipsychotics
reduced sedative effects compared to the others
negatives to first generation antipsychotics
they have no effect on negative or cognitive symptoms, ineffective in 30% patients, relapse rate, intolerable side effects (cardiotoxicity)
VTA dopamine pathway is involved in…
reward, psychosis and movement
Effect of 1st Gen antipsychotics on nigrostriatal dopamine system?
decreased DA (blocking of D1 receptors) results in impaired movement (Parkinson’s symptoms)
pyramidal
voluntary movement
extrapyramidal
subconscious movement (nigrostriatal DA system)
why 1st Gen antipsychotics caused extrapyramidal side effects
blocked 80% of d2 receptors = antipsychotic
also had an effect on D1 receptors responsible for movement (causing extrapyramidal side effects)
2nd Gen Typical Antipsychotic
Benzamides
Action of benzamides
highly selective for D2 receptors meaning less extrapyramidal side effects but still no effect on negative or cognitive symptoms
Suspected Involvement of Serotonin in Schizophrenia
- modulates mesocorticolimbic DA system
- may encourage DA deficit in PFC
- increases DA release in NA
drugs activating 5-HT2 receptors produce…
schizophrenia like symptoms
Atypical antipsychotics benefits
attenuates both positive and negative systems, no extra pyramidal side effects
Atypical antipsychotics negatives
agranulocytosis - suppression of immunity
types of atypical antipsychotics
multiple receptor antagonists (differing affinities)
Selective 5-HT2/ D2 antagonists
How is glutamate involved in schizophrenia
glutamate neurotransmission is reduced, glutamate opens NDMA receptors, reducing this induces psychosis as NDMA receptors aren’t opened letting in Glut to excite GABA to reduce GLut again in PFC
Novel Antipsychotics
NMDA receptor modulators