Ethanol and the CNS

Question 1

Describe the chemical properties of ethanol

Answer 1

has only one hydrogen donor/acceptor so doesn’t form high affinity bonds
A small molecule so squeezes into small intramolecular spaces
Partitions equally in water and lipid
Diffuses well across biological membranes

Question 2

Describe a ‘unit’ of alcohol

Answer 2

8g or 10ml of pure ethanol
25ml spirit
half pint of beer
small glass of wine

Question 3

List the scale of effects of alcohol

Answer 3

Loss of shyness 
Lower inhibition & feel good 
Balance and control impaired 
significant motor issues, slurred speech 
Loss of physical control 
Dysphoria 
Needs help walking, vomiting
Loss of consciousness
Coma and death

Question 4

what is the overall effect of ethanol on the CNS

Answer 4

Depressant

Question 5

What are the molecular targets in the brain for ethanol

Answer 5

Inhibitory receptors such as glycine and GABA - will increase these
Excitatory receptors such as glutamate, acetylcholine and 5HT

Question 6

Describe the GABA receptors

Answer 6

Part of the Cys-loop family 
Made of 5 subunits 
These can vary widely - up to 20 types 
A major inhibitory receptor 
Different subunits have different effects and different sensitivity to ethanol

Question 7

How are the GABA receptors affected by alcohol

Answer 7

They are positively modulated by ethanol - effect increased

delta subunit particularly sensitive

Question 8

Describe the glutamate receptors

Answer 8

Part of their own family
Made of 4 subunits
Major excitatory receptor

Question 9

How are the glutamate receptors affected by alcohol

Answer 9

It is the NMDA subtype of glutamate that is susceptible Ethanol will decrease the excitatory response

Question 10

What is the main reward pathway in the brain

Answer 10

mesolimbic dopaminergic pathway
dopamine is released as a neurotransmitter from the VTA in the brain
It passes to the nucleus accumbens which can send the signal to other brain regions

Question 11

What is the link between alcohol and the reward pathway

Answer 11

It is thought to activate the system and this is the cause of dependence
Ethanol inhibits the reuptake of dopamine

Question 12

How is the CNS affected during alcohol withdrawal

Answer 12

In alcoholics there is an upregulation of NMDA and downregulation of GABA
When ethanol is removed there is a big imbalance which leads to anxiety, dysphoria and seizures