Lecture 21: Psychopharmacology Flashcards
What is synaptic transmission?
How neurons communicate by sending chemicals (neurotransmitters) across synapses.
How can drugs affect synaptic transmission?
Interfere at different stages:
* Action potential propagation
* Neurotransmitter release
* Binding at receptors
* Inactivation or reuptake
What is an action potential?
An electrical signal that travels down the axon.
How can drugs block action potentials?
Tetrodotoxin (TTX) blocks sodium channels, preventing the signal.
What is the effect of TTX?
Causes paralysis (including diaphragm) and can be fatal — over 10,000 times more toxic than cyanide.
How do toxins affect neurotransmitter release?
Some block neurotransmitter release:
* Tetanospasmin blocks GABA release → causes tetanus
* Botulinum toxin blocks acetylcholine release at nicotinic receptors → causes paralysis
How do amphetamines increase dopamine?
Resemble dopamine, enter neurons via dopamine transporters, and cause vesicles to release more dopamine.
What is the effect of amphetamines on the reward system?
Overstimulates reward system (VTA to Nucleus Accumbens) → pleasure, addiction.
What is an agonist?
Imitates neurotransmitter, activates receptor (e.g., heroin, nicotine, THC).
What is an antagonist?
Binds without activating, blocks the real transmitter (e.g., curare, some antipsychotics).
How do agonists and antagonists bind to receptors?
They can bind to:
* Competitive (same site)
* Non-competitive (different site)
How does heroin work in the brain?
Modified morphine, an agonist for endorphins, binds to opiate receptors causing pain relief, relaxation, and euphoria.
How does marijuana (THC) affect the brain?
Agonist for anandamide, binds to cannabinoid receptors → affects emotion, appetite, pain, memory.
How does nicotine affect the nervous system?
Agonist for acetylcholine at nicotinic receptors, stimulates the system briefly → increases adrenaline and alertness.
How does caffeine work?
Blocks adenosine receptors, increases alertness by stopping inhibition, prevents cAMP breakdown.
What are the effects of low doses of alcohol?
Alcohol is a GABA agonist, enhancing inhibition → calm, relaxed.
What are the effects of high doses of alcohol?
Inhibits too much, causes sedation, possible brain cell death.
What role does GABA play in anxiety?
Anxiety disorders may involve low GABA activity.
How are anxiety disorders treated?
Benzodiazepines (e.g., Valium) are GABA agonists → increase GABA’s calming effects.
How is depression linked to neurotransmitters?
Caused by low levels of serotonin, dopamine, and noradrenaline.
What are MAO inhibitors?
Stop enzymes breaking down serotonin, dopamine, and noradrenaline.
What do tricyclics do?
Stop reuptake of serotonin, dopamine, and noradrenaline.
What do SSRIs do?
Selectively block serotonin reuptake → fewer side effects.
What is schizophrenia linked to?
Excess dopamine → hallucinations, paranoia.
How is schizophrenia treated?
With neuroleptics (e.g., Haldol) = dopamine antagonists that block receptors.
How does cocaine affect the brain?
Blocks reuptake transporters for dopamine and noradrenaline, boosting their effect.
What are the effects of cocaine at high doses?
Intense stimulation, pleasure, addiction, can mimic schizophrenia symptoms.
How do amphetamines and ecstasy (MDMA) affect neurotransmitters?
Block reuptake of dopamine, noradrenaline, and serotonin, inhibit enzymes that break them down.
What is the overall effect of amphetamines and ecstasy?
Huge boost in neurotransmission, mood elevation, stimulation.
Why can drugs for Parkinson’s and schizophrenia cause opposite effects?
Parkinson’s = low dopamine → treatment increases dopamine; Schizophrenia = too much dopamine → treatment reduces dopamine.
What psychoactive substances are found in chocolate?
Contains anandamide (THC-like) and phenylethylamine (like amphetamine).
What is the effect of psychoactive substances in chocolate?
Amounts are tiny, effects are psychologically pleasurable more than chemical.
