Option A - Neuropharmacology

Question 1

What are psychoactive drugs?

Answer 1

They affect the brain and personality by either increasing or decreasing postsynaptic transmission.

Question 2

How do psychoactive drugs affect the brain?

Answer 2

1. Increase or decrease the release of neurotransmitters
2. Breakdown re-uptake proteins which are responsible for returned used components of NT to the presynaptic neuron (ready to use again).
3. Block re-uptake proteins so the NTs remain in the synapse.
4. Mimic or block NTs, binding to the receptors on postsynaptic membranes.
5. Inhibit production of new NTs.

Question 3

What are stimulant drugs and examples of them?

Answer 3

They increase postsynaptic transmission. Nicotine, amphetamines and cocaine.

Question 4

What is the effect of cocaine?

Answer 4

Without cocaine, dopamine is reuptaken by pumps on the presynaptic membrane.
With cocaine, cocaine blocks re-uptake pumps. Dopamine remains in synaptic cleft. More dopamine continues to be released. Summative increase in postsynaptic transmission.

Question 5

What is cocaine’s effect on mood?

Answer 5

Dopamine is involved in reward pathways and causes enhanced feelings of pleasure, which has longer than normal.

Question 6

What is the effect of cocaine on behaviour?

Answer 6

• Feelings of euphoria
• Increase energy and alertness
• Highly additive
• Association with depression as body reduces production of own dopamine overtime

Question 7

What is the effect of nicotine?

Answer 7

Without nicotine, dopamine is reuptaken by pumps on the presynaptic membrane.
With nicotine, nicotine mimics the action of ACh; it binds to ACh receptiors triggering action potential in the postsynaptic neuron. Unlike ACh, nicotine is not easily broken down and remains in synaptic cleft and continues to stimulates postsynaptic neuron.

Question 8

What is nicotine’s effect on mood?

Answer 8

ACh causes the release of dopamine, which in turn causes enhanced feelings of pleasure

Question 9

What is nicotine’s effect on behaviour?

Answer 9

• Feelings of euphoria
• Increase calmness and alertness
• Addictive - as the brain develops a tolerance for nicotine, it become s needed for normal functioning.

Question 10

What are sedative dugs and examples of it?

Answer 10

They decrease postsynaptic transmissions. Alcohol, benzodiazapines, THC.

Question 11

What is the effect of tetrahydrocannibol (THC)?

Answer 11

Without THC, dopamine release is moderated (inhibited) by GABA.
With THC, it mimics anandamide cannabinoids and inhibits GABA release by binding to cannabinoid receptors. GABA cannot inhibit dopamine release therefore more dopamine is released.

Question 12

What is the effect of THC on mood?

Answer 12

Dopamine is involved in reward pathways and causes enhanced feelings of pleasure.

Question 13

What is effect of THC on behaviour?

Answer 13

• Intoxication
• Hunger
• Memory impairment
• Potential dependency

Question 14

What is the effect of alcohol on the body?

Answer 14

Without Alcohol, GABA inhibits the post-synaptic transmission. Glutamate is an excitatory NT that binds to receptors increasing post-synaptic transmission.
With Alcohol, it increases the inhibitory effect of GABA by causing GABA to remain bound to it’s receptor for longer. Alcohol binds to glutamate receptors preventing glutamate from stimulating the the post-synaptic neuron.

Question 15

What is the effect of alcohol on the mood?

Answer 15

Alcohol indirectly causes a dopamine release that in turn causes enhanced feelings in pleasure.

Question 16

What is the effect of alcohol on the behaviour?

Answer 16

• Calm relaxed feeling
• Memory impairment
• Increases (worsens) reaction speeds
• Affects breathing, body temperature regulation and appetite
• Potential dependency

Question 17

What are anaesthetics?

Answer 17

Anaesthetics are very varied group of molecules that affect neural pathways in different ways, which cause a temporary loss of sensation.

Question 18

What are the types of anaesthetics?

Answer 18

Local - cause numbness (a loss of sensation) in an area of the body.
General - cause unconsciousness and therefore a lack of sensation throughout the body.

Question 19

What are the risks of general anaesthetics?

Answer 19

They block ‘long-distance communication’ hence affecting (often inhibiting) the transmission of impulses from receptors (areas of sensory perception) and the CNS.

Question 20

What is addiction?

Answer 20

Dependence on a substance or activity resulting in its repeated and compulsive use.

Question 21

What are some causes of drug addiction?

Answer 21

• Genetic predisposition
• Dopamine secretion
• Social environment factors

Question 22

Describe genetic predisposition

Answer 22

• Many genes with roles in addiction have been identified
  (with the help of animal models, especially mice)
• For example the A1 allele of the dopamine receptor gene
  DRD2 is more common in people addicted to alcohol or
  cocaine.

Question 23

Describe dopamine secretion

Answer 23

• Dopamine activates pleasure pathways of the brain, it is normally released to reward positive behaviours.
• Many drugs affect, often enhancing, dopamine activity (e.g. cocaine, heroin)
• Abuse of some drugs to lead to down-regulation of dopamine receptors, requiring higher doses to achieve same effect (habituation)

Question 24

Describe social environment factors

Answer 24

• The social environment plays a significant role; individuals raised
in environments with prevalent substance abuse are at a higher risk
• Peer pressure (from those that use drugs), poverty and social deprivation, traumatic life experiences and mental health all make drug addiction more likely
• Culture, religion and traditions can both positively and negatively affect addiction and this in part explains the variation in addiction patterns found between different countries