Pharmacology of Psychoses - Mood Disorders Flashcards
Explain the dopamine theory of schizophrenia and its limitations.
hypothesis = abnormality in brain function in schizophrenics is due to overactivity in
brain dopaminergic pathways, especially in mesolimbic pathway
limits = a) Postmortem and in vivo imaging studies show diminished DA activity in cortical and hippocampal regions that may underlie negative symptoms and cognitive impairment
b) Clozapine is weak D2 blocker but still is an effective antipsychotic agent
c) Evidence exists for role of serotonin (5-HT) and glutamate neurotransmitter systems (via modulation of dopamine neurotransmission)
Describe the mechanism of antipsychotic drug action.
Virtually all effective antipsychotics block CNS dopamine receptors (postsynaptic D2).
Name the brain dopamine systems affected by antipsychotic drugs.
1: Mesolimbic pathway
2: Mesocortical pathway
3: Nigrostriatal pathway
4: Tuberoinfindibular pathway
Describe the mesolimbic pathway.
integration of sensory input and motor responses with affective or emotional data
Hyperactivity in this pathway is believed to
contribute to the occurrence of positive symptoms
Tx = antipsychotics (via D2 receptor blockade)
Describe the mesocortical system.
Cortical structures (dorsolateral prefrontal cortex and ventromedial prefrontal cortex) are involved in communication and social abilities.
Hypoactivity due to cell loss in the prefrontal cortex contributes to presence of negative symptoms.
Tx = atypical antipsychotic agents such as clozapine or olanzapine (via additional block of 5HT2A receptors)
Describe the nigrostriatal system.
This dopaminergic tract is part of a larger subcortical circuit known as the basal ganglia and plays a central role in planned, coordinated movement.
Loss of dopamine in this region results in dysregulation of movement (Parkinson’s disease –> hypoactivity,
bradykinesia, and tremor).
Tx = dopaminergics
Describe the tuberoinfundibular system.
Hypothalamic neurons release DA in pituitary to inhibit prolactin release.
What integrates sensory input and motor responses with affective or emotional data?
the mesolimbic pathway
Collectively, these cortical structures (dorsolateral prefrontal cortex and ventromedial prefrontal cortex) are involved in communication and social abilities.
the mesocortical system
Loss of dopamine in this region results in dysregulation of movement (Parkinson’s disease –> hypoactivity,
bradykinesia, and tremor).
the nigrostriatal system
_____ drug use (via ______) can result in unwanted extrapyramidal side effects
Antipsychotic via D2 dopamine receptor blockade
What are antipsychotic drug side effects called?
extrapyramidal side effects
What are extrapyramidal side effects?
antipsychotic drug side effects
______ neurons release DA in pituitary to inhibit prolactin release.
Hypothalamic
Hypothalamic neurons release ______ in pituitary to inhibit prolactin release.
DA
