Effects of recreational drugs

Question 1

What is the advantage of the theory of the effect of recreational drugs?

Answer 1

Credited by research using non-human animals supporting the role of dopamine

• Weinsheker and Schroeder deliberately damaged the reward pathway in mice brains, so that the neurons are unable to produce levels of dopamine normally associated with reward.
• When this is done, the mice then fail to self-administer cocaine intravenously (through a vein)
• This does not occur when the lesions are performed in other parts of the brain
• This finding supports the view that cocaine’s effects are due to the activity of dopamine in the brain’s reward system

Question 2

What is the real-world application of the theory of recreational drugs

Answer 2

Real-world application to improving treatment for addiction

• Once heroin was identified as an agonist that binds to opiate receptors, other drugs were developed with a reverse mode of action
• Naloxone is an antagonist drug that blocks opiate receptors and prevents heroine from occupying them
• Naloxone doesn’t produce the rewarding euphoria associated with heroin, so it can help manage the withdrawal process and reduce symptoms
• This is a treatment developed from greater knowledge of the transmission effect of drugs

Question 3

What is the disadvantage of the theory of recreational drugs

Answer 3

A weakness is that non-human animal studies have a low validity in explaining drug effects on human CNS transmission

• The basis of transmission processes in mammals are similar, but there are some differences because the human brain is more complex than a rat brain
• For example, isolating the effects of just one neurotransmitter oversimplifies the process, it is very unlikely that the complex recreational drugs effects on transmission can be explained by just one mode of action of a drug
• The interactions of dopamine with other neurotransmitter systems aren’t well understood
• This means that the comparison of non-human animals to humans is risky and should be approached cautiously

Question 4

What are the long-term effects of heroin?

Answer 4

Downregulation, opioid receptors on postsynaptic neurons are constantly binding with morphine molecules, which desensitizes them to the effects of the drug - this is the basis of tolerance

Question 5

What is an antagonist drug that blocks opiate receptors

Answer 5

Naloxone is an antagonist that blocks opiate receptors

Question 6

Explain how heroin works

Answer 6

1. It has a depressant effect on the CNS, it slows down CNS activity including the activity of neurons involved with pain
2. Once it reaches the brain it’s processed into morphine
3. Morphine binds with a specific opioid receptor at the synapse found in the cerebral cortex, limbic system, and hypothalamus
4. These specific opioid receptors would bind to endorphins as natural pain killers
5. Heroin binds to the receptors of the natural opioid system to massively enhance the natural response

Question 7

Define recreational drugs

Answer 7

Recreational drugs include stimulants, sedatives, hallucinogens, and opioids.
Each drug operates in a similar way, increasing or decreasing a specific neurotransmitter at the synapse to create euphoria.

Question 8

Explain what the role of dopamine is in cocaine use?

Answer 8

1. Cocaine blocks the reuptake of dopamine by binding with dopamine transporter molecules on the terminal buttons of the presynaptic neuron - these are responsible for recycling dopamine back into the neuron that produced it
2. Cocaine prevents this so the synapse is flooded with dopamine which are all available to bind with postsynaptic receptors
3. This causes euphoria

Question 9

Explain how cocaine works

Answer 9

1. Cocaine has a stimulant effect on the CNS, especially on the neurons of the brain’s main reward system.
2. The drug achieves its effects by altering the synaptic transmission of dopamine

Question 10

What are the long-term effects of cocaine?

Answer 10

1. Dopamine receptors become downregulated, so fewer receptors are active as some are damaged or shut so the quantity of dopamine produced declines
2. This means that there will be higher withdrawal symptoms and higher doses needed to get the same effects as tolerance to the drug increases

Question 11

Describe heroin as an agonist drug

Answer 11

Heroin is an agonist drug because it mimics the action of another natural biochemical