PHRM 845-Exam 4 (Watts Lecture) Flashcards
Schizophrenia/Psychotic Disorders
Schizophrenia may be due to …
-Nurturing
-Family orientation
-Interactions growing up
-Environment
-School experience
History and Background of treating schizophrenia:
-Early 1900’s:____
-Before 1950’s, tx included ____
-1950’s tx: ____
-1952 tx:____
-Early 1900’s: Brain disease
-Before 1950: Sedation (if sleeping, don’t have to deal with +/- sx); lobotomy (remove piece of cortex); ECT (depolarizing all of the neurons and ‘restarting’); Rauwolfia alkaloids used in Hindu Medicine
-1950: Riserpine
-1952: Phenothiazines (chlorpromazine): dopamine receptor antagonist **Could manage symptoms and helped empty mental hospitals.
General considerations of schizophrenia: split from reality
Antipsychotic=neuroleptic=anti-schizophrenic
-Severe illness; most debilitating of psychotic disorders.
-Affects 1% of the population (world-wide)
-Onset age: 15-20 y/o
-Not split personality!
Etiology of schizophrenia
**We don’t know what causes schizophrenia, but these increase risk
-Neurodevelopmental/
anatomical (in-utero adolescence-increased ventricle size and changes in gray/white matter)
-Genetics (neuronal growth; migration of neurons)
-Environmental: birth complications, infections
-Gene-environment interaction: COMT-marijuana
-Neurodevelopmental-environment interaction
Genetics of schizophrenia
-If a twin has it, you have a ___ % chance of getting it
-If a family member has it, you have a ___% chance of getting it
50%
10%
Interaction for gene-environment interaction in schizophrenia
Catechol methyltransferase mutation and marijuana (25% increased risk)
Outward expressions of schizophrenia
-Thoughts are loosely connected
-Disturbances in mood
-Global impairment is the biggest psychological function
Positive symptoms in schizophrenia
-Respond well to drug therapy
-Hallucinations (seeing/hearing things that aren’t there)
-Delusions (think they are the most important person/fear of persecution)
-Bizarre behavior (twisting hair)
-Thought disorders (word salad)
Negative symptoms of schizophrenia
-Little response to drug therapy
-Newer agents are better
-Blunted emotion (pulling away from loved ones)
-Poor self care (stop bathing)
-Social withdrawal
-Poverty in speech
-Lack of movement
Cognitive symptoms of schizophrenia
-Decrease in cognitive function
-Involves D1 and glutamate receptors
-Decrease in ability to use executive function/planning
Neurotransmitter hypothesis in schizophrenia
-Dopamine: first to be developed, but incomplete
-Serotonin: based on mechanism of LSD and mescaline (2 hallucinogenic functions)
-Glutamate: based on phencyclidine and ketamine (used for tx-resistant depression)
Serotonin hypothesis for schizophrenia
**14 total serotonin; 13 ion channel and 1 GPCR
- LSD and mescaline were identified as 5HT agonists, inspired search for ‘endogenous’ hallucinogens
- Pharmacological studies with 5HT receptors identified 5HT2A receptor as mediator of hallucinations
- Antagonism and inverse agonism linked to antipsychotic activity
- 5HT2A receptors modulate dopamine release in cortex, limbic region, and striatum
- 5HT2A receptors modulate glutamate release and NMDA receptors.
- 5HT2C agonists may be beneficial in schizophrenia
Glutamate hypothesis of schizophrenia
- Glutamate is a major excitatory neurotransmitter (crank up neuronal activity–allow positive ions in)
- Phencyclidine and ketamine, noncompetitive inhibitors of NMDA receptors, exacerbate psychosis and cognition deficits.
Dopamine hypothesis for schizophrenia
*Most evidence for this
*Influenced by serotonin and glutamate
- D2 receptor antagonists: strong correlation receptor binding affinity vs. clinical effectiveness.
- Dopaminergic agents (L-DOPA, amphetamine, bromocriptine) exacerbate symptoms of schizophrenia.
- Increased D2 receptor density in treated and untreated patients of schizophrenia.
- Imaging studies-increased DA release and receptor occupancy in pts.
- Dopamine metabolites in CSF-D2 receptor antagonists initially increase metabolites in the CNS and later decrease metabolites in CNS.
Determining binding affinity: intermolecular force between ligand and receptor
-Low number=tight binding=high affinity
-Kd/Ki is the estimated concentration at which 1/2 of the receptors are occupied.
-Saturation binding experiments: vary concentration of radio-labeled ligands.
-Competition binding experiments: constant radioligand (hot) concentration competing with unlabeled ligand (cold).
Receptors antagonized by anti-psychotics
Major: Dopamine
Newer agents: Serotonin
Minor: NE, ACh, Histamine
Dopamine receptor breakdown
D1-like (D1 and D5)
D2-like (D2-D4)
Serotonin receptor antagonists
Clozapine
Olanzapine
Risperidone
Older agents: chlorpromazine, haldol, thioridazine
Effects of alpha-1 and alpha-2 receptor blockade from NE receptor antagonism
Alpha-1: hypotension, sedation (SE)
Alpha-2: may be helpful in tx
Acetylcholine receptor antagonism
Muscarinic receptors which will produce anticholinergic effects (clozapine, thioridazine)
Histamine receptor antagonism effects
H1 receptor antagonism: sedation & weight gain
-Ex: taking benadryl when stung by a bee–want to take a nap and eat chips
Which receptor is key for therapeutic effectiveness in tx schizophrenia?
We don’t know (all unique receptor MOA); likely involves multiple receptors; spectrum of schizophrenia which would require different receptors.
-Unable to predict effectiveness of each therapy for individual patient.
-Multiple receptors=many SE=poor adherence
Binding affinity vs clinical dose for dopamine antagonists
-Correlation between binding potency and clinical effectiveness for D2 receptors, therefore more effective drug target.
-Not much of a correlation with D1-like receptors (D1 and D5)
-Almost perfect correlation with D2-like receptors (D2-D4); ability of antipsychotics is predictive based on dose.
-Most antipsychotics are receptor antagonists
Dopamine physiology and function: actions of D2 antagonists in CNS
-Basal ganglia (nigrostriatal pathway): Motor effects (if no dopamine, get extrapyramidal sx)
-Mesolimbic: primary therapeutic effects (the only ones we really want to block)
-Mesocortical: hypofunction in schizophrenia, antagonists may exacerbate cognitive deficits
-Hypothalamus and endocrine systems: D2 receptor blockade in endocrine system (in hypothalamus, there is a change in prolactin secretion–increase in release of prolactin when blocked)
-Medulla: chemoreceptor trigger zone (nausea/vomiting); D2 antagonists are anti-emetics
