CB L2 - Drug addiction 2

Question 1

What receptor is thought to be responsible for conscious perception of euphoria?

Answer 1

D2 - eventually projects to the prefrontal cortex

Question 2

How do we use PET scanning used to look at DA conc

Answer 2

infuses radio ligand for DA receptors.
If something happens to cause release of DA competing with this there is less radio ligand binding
If there is fewer receptors also less binding

Question 3

What does PET scanning show on admin of methylphenidate?

Answer 3

DA response to methylphenidate is less in normal than cocaine abusers.

Question 4

Are addicts born with less D2 receptors of is this a response to drug abuse?

Answer 4

Study gave non-addicts methyl phenidate and PET scanned:

Some people didn’t enjoy (heart racing), these people had more D2 recptor.

People who enjoyed it had fewer D2 receptors

Question 5

Are addicts born with less D2 receptors of is this a response to drug abuse?

Answer 5

Study gave non-addicts methyl phenidate and PET scanned:

Some people didn’t enjoy (heart racing), these people had more D2 recptor.

People who enjoyed it had fewer D2 receptors

Question 6

So how could number of receptors be a risk factors to becoming an addict?

Answer 6

Fewer D2 receptors in addicts and non-drug abbuser who enjoyed the methyl phenidate expereince

Question 7

Cocaine self-administration for rats with high vs low D2 receptors showed…

ref?

Answer 7

Rats with lower D2 density took more cocaine than those with lower D2 density

Dalley, (2007)

Question 8

Chronic cocaine admin in mokeys over 1 year showed…

ref

limitations?

Answer 8

decline in D2 expression.

Nader, 2006

might only apply to pyschostimulants as other drugs havent been investigated

Question 9

Over all the D2 concentration studies indicate:

Answer 9

People with fewer D2 receptors might have a greater drive to take rewarding drugs (might like them more)

Question 10

How could a SNP affect D2 expression? (in theory)

Answer 10

reduced expression of D2 receptor.

But this is also affected by you environment

Question 11

How could a SNP affect D2 expression? (in theory)

Answer 11

reduced expression of D2 receptor.

But this is also affected by you environment

Question 12

Put an animal in an unrewarding cage (no toys/isolation/boring food) - what happens?

ref?

Answer 12

Decreases D2 levels and increases cocaine self-administration.

Nader 2006

Question 13

Mokeys live in packs - dominant levels of D2 are higher/lower?

Answer 13

higher - less likely to take cocaine.

So maybe your environment causes changes to expression levels?

Question 14

Intrudedr test is

Answer 14

putting monkeys in a cage, introduce an intruder and monkeys throw poo at it, only works if intruder is submissive, otherwise it throws poo.

Dominant monkeys hardly took cocaine. For the submissive monkeys this is really unpleasant so took a fuck tonne.

Dominant already had their reward and felt good?

Question 15

So the D2 receptor levels affefted by the environment suggests the best way to treat addicts is…

Answer 15

by changing their environment!

Question 16

Outline of Low D2 receptor levels whole theory:

may be the case for other drugs but atm only looked at psychostimulants

Answer 16

Not much reward in your life (environmental factors) and genetic factors lead to low D2 levels.

Low endogenous reward ‘tone’

Enhanced ‘liking’ of drugs of abuse

Enhanced drug intake

Question 17

Outline of Low D2 receptor levels whole theory:

may be the case for other drugs but atm only looked at psychostimulants

Answer 17

Not much reward in your life (environmental factors) and genetic factors lead to low D2 levels.

Low endogenous reward ‘tone’

Enhanced ‘liking’ of drugs of abuse

Enhanced drug intake

Question 18

So enhancing reward might decrease use of drugs of abuse…. economical?

Pharmacological treatments suggested? (2)

Answer 18

yes - costs loads to treat addicts

Bupropion - (NA/DA reuptake inhibitor)
Bromocriptine (partial D2 agonist)
maybe mrore effective in people with certain D2 SNP?

Question 19

Problems with the D2 receptors hypothesis 3

Answer 19

1. There are D2 receptors everywhere so we are assuming the ones in the NAcc are most important.
2. Lots of other brain regions involved such as memory
3. Taking drug is no longer for euphoria - emotion and copulsion elements.

Question 20

Memory formation is thought to occur through

Answer 20

synaptic plasticity.

Question 21

Psychological dependence (addiciton, craving) must have a ……. component

Answer 21

learned

Question 22

How is DA release a predictor of reward - human example

ref

Answer 22

DA gets released as you anticipate taking the the drug.
If you show addicts films of people taking the drug they release DA (doesn’t happen in non-addicts)

volkow, 2006, 2011

Question 23

How is DA release a predictor of reward - animal example

ref

Answer 23

DA gets released when the lever appears in animal models (higher spike than actual reward from drugs).

During extinction this still occurs, but animal doesn’t get cocaine. Over time DA release wains,