Effect of Recreational Drugs

What kind of drug is cocaine?

Stimulant

What effect does cocaine have?

Excitatory

What does cocaine do?

Blocks the reuptake of dopamine into the pre-synaptic neuron

What happens when reuptake is blocked?

The synapse is flooded with too much dopamine which will bind to the post-synaptic neuron, this causes euphoric high

What happens after repeated cocaine use?

Dopamine receptors become down regulated

What happens when receptors are down regulated?

Fewer receptors will be active (some damaged and some shut down) which cause dopamine production to decline

What is dopamine?

Neurotransmitter which regulates motivated behaviour and how we experience reward

What is the charge for excitatory neurons?

Positive, more likely to fire

What effect does heroin have?

depressant effects on the CNS, slowing down activity, e.g., that of neurons involved in pain

What type of drug is heroin?

opioid

What does heroin bind to?

morphine, which then binds to specific opioid receptors

What happens when heroin binds with the receptors of the natural opioid system?

it massively enhances the body’s natural pain-killing response

Why is heroin an agonist drug?

it mimics the action of another biochemical

What happens after long-term use of heroin?

the receptors become desensitised to the drug

What did Weinshenker and Schroeder (2007) do?

deliberately damaged the mesocorticolimbic pathway in mice brains so that the neurons were unable to produce levels of dopamine

What did Weinshenker and Schroeder find?

the mice then fail to administer cocaine intravenously, which shows cocaine’s effects are due to dopamine’s activity in the brain

What is the issue with using animal studies to understand drug effects on the CNS?

the human brain is more complex than the rat brain

What did Volkow et al (1997) do?

used PET scans to track activity of dopamine transporters during a cocaine-induced highW

What did Volkow find?

a positive correlation between cocaine occupied dopamine transporters and the subjective experience, demonstrating the role of dopamine in a human brain

Give an example of a drug treatment.

naxolone is an antagonist drug which blocks opiate receptors and prevents heroin from occupying them