Alcohol and the CNS Flashcards
How does alcohol create rewarding effects?
It enhances dopamine release
How does alcohol affect the brain at lower doses (<50mg/dL)
It activates arousal mechanisms in the brain stem reticular
What effect does the GABA system have?
It has an inhibitory effect
How does alcohol work on the GABA system?
It is a positive allosteric modulator
How does alcohol affect the CNS?
It has a depressive effect on the CNS
At what dose does alcohol cause sedation?
Blood concentrations of 300-350mg/dL
What is the result of concentrations between 350-400mg/dL?
Respiratory depression
At what blood concentration can death occur?
400 mg/dL or higher
How does alcohol affect the Mesocorticolimbic Dopamine Pathway?
Decreases firing in the pre-frontal cortex, which decreases firing of GABA receptors in the Ventral Tegmental area and increases the firing of Glutamate receptors, causing a release of dopamine in the Nucleus Accumbens
What is the GABAa receptor?
An ion channel
How does alcohol effect the GABAa receptors?
It prolongs the length of time the channels are open for
How does the GABAa receptor work?
It opens and chlorine enters, which causes hyperpolarisation in the CNS
What is benzodiazepine?
Drug class that works in a similar way to alcohol (increases the influx of chlorine); used to treat alcohol withdrawl
How does chlorine effect the GABA system?
It causes inhibition once released
Where does GABA bind?
Post-synaptic GABAa receptors
What happens with chronic alcohol use?
There are fewer GABAa receptors as they are internalised
How does alcohol tolerance arise?
Alcohol keeps channels open for longer and compensates for the fewer number which maintains normal inhibition
What happens when alcohol is removed in someone who has developed tolerance?
There is no longer sufficient inhibitory signalling so there is increased susceptibility to seizures
What is Lorazepam used for?
Alleviates seizures
Why does cross-tolerance develop?
Both alcohol and the drugs used to treat it have the same targets
