4. Drugs

Question 1

4 Methods of Administration

Answer 1

Ingestion
Absorption
Inhalation
Injection

Question 2

Ingestion

Answer 2

1. Goes through the digestive system into the intestines, where they are absorbed into the blood
2. Relatively safe & easy but unpredictable (food intake and other factors affect rate)

Question 3

Absorption

Answer 3

Through mucus membranes

Question 4

Inhalation

Answer 4

1. e.g. smoking
2. Cannot regulate dose
3. Damage to lungs if done incorrectly
   
   1. Absorbed into the blood from the lungs

Question 5

Injection

Answer 5

1. Into muscles, fatty tissue or veins
2. Intravenous - blood stream takes them straight to the brain
   
   1. Little to no opportunity to counteract an overdose or allergic reaction
   2. Scar tissue, collapsed veins and infections are also a risk

Question 6

Drug penetration of the CNS

Answer 6

• Travel through the bloodstream to blood vessels of the CNS
• Blood-brain barrier makes it difficult for drugs to get past into the “extracellular” space surrounding the neurons and glia of the CNS
• Drugs like alcohol & many general anesthetics diffuse across neural membranes (nerve cells)

Question 7

Drug metabolism

Answer 7

Enzymes in the liver convert active drugs to non-active forms
Most cases: inhibits the drugs ability to pass through lipid membranes, meaning it can no longer get past the blood-brain barrier

Question 8

Agonists

Answer 8

Drugs that facilitate the effects of a specific neurotransmitter e.g. a dopamine agonist
Activate certain receptors

Question 9

Antagonists

Answer 9

Drugs that inhibit the effects of a specific neurotransmitter e.g. a dopamine antagonist
Block certain receptors

Question 10

Affinity & Efficacy

Answer 10

Affinity - tendency to bind to a receptor
Efficacy - tendency to activate a receptor

A drug that binds easily but does not stimulate would be high in affinity and low in efficacy
This would also be an antagonistic effect

Question 11

Mesocorticolimbic System

Answer 11

a component of the mesotelencephalic dopamine system which play an important part in mediating ICSS (Intracranial self-stimulation)

1. Self-stimulation occurs at many brain sites that are part of the mesocorticolimbic system
2. ICSS is associated with spikes in dopamine release in the mesocorticolimbic system
3. Dopamine agonists increase ICSS and dopamine antagonists decrease ICSS
4. ICSS is disrupted when there are lesions (abnormal tissue growth) in the mesocorticolimbic system

Question 12

Intracranial self-stimulation

Answer 12

self-administration of weak electrical stimulation to the brain
- Think rats and levers

Question 13

Ventral Tegmental Area (VTA)

Answer 13

The cell bodies of the neurons composing the MDS (Mesotelencephalic Dopamine System) are contained here and in the substantia nigra
- Axons of the neurons in the VTA mostly project into many cortical and limbic sites
- This section of the MDS is called the Mesocorticolimbic system

Question 14

Nucleus Accumbens

Answer 14

‘Reward centre’
Motivation (anticipation of reward) and reward
‘Dopaminergic’ input is sent from the VTA to the nucleus accumbens - strongest, clearest relation to reward and pleasure
- Lesions in this area stopped rats administering drugs to themselves

Question 15

Subcutaneous Injection

Answer 15

Into fatty tissue

Question 16

Intramuscular Injection

Answer 16

Into large muscles

Question 17

Intravenous Injection

Answer 17

Into veins

Question 18

Amphetamine

Answer 18

Blocks reuptake of dopamine & several other transmitters

Question 19

Cocaine

Answer 19

Blocks reuptake of dopamine + others
Stimulant

Question 20

Methylphenidate (Ritalin)

Answer 20

Blocks reuptake of dopamine + others, gradually

Question 21

MDMA (Ecstasy)

Answer 21

Releases dopamine & serotonin

Question 22

Nicotine

Answer 22

Stimulates nicotinin-type acetylcholine receptor, increasing dopamine release in the nucleus accumbens

Question 23

Opiates (e.g. heroine, morphine)

Answer 23

Stimulates endorphin receptors

Question 24

Cannabinoids (marijuana)

Answer 24

Excites negative-feedback receptors on presynaptic cells; ordinarily responding to anandamine & 2AG

Inhibits GABA & glutamate, leading to dopamine release
Psychoactive effects due to TCH
Antagonist

Question 25

Hallucinogens

Answer 25

Stimulate serotonin type 2A receptors

Question 26

Burgers' Disease

Answer 26

Blood vessels (particularly in the legs) become constricted, possibly leading to amputation

Question 27

Alcohol

Answer 27

Depressor GABA agonist - facilitates response at receptors Glutamate antagonist - blocks activity at receptors, leading to decreased brain activity

Question 28

Drug tolerance

Answer 28

Decreased sensitivity to a drug due to exposure to it There is no 1 mechanism that leads to this

Question 29

Dose-response curve

Answer 29

A graph demonstrating the effect sizes of different doses of a drug

Question 30

Cross tolerance

Answer 30

Tolerance to one drug can lead to tolerance to other drugs of the same type (that work by the same mechanisms)

Question 31

Drug sensitization

Answer 31

we become increasingly sensitive to certain effects of a drug, often as we gain tolerance in others

Question 32

2 categories of changes facilitating drug tolderance

Answer 32

Metabolic tolerance Functional tolerance

Question 33

Metabolic tolerance

Answer 33

Changes that reduce the amount of the drug reaching sites of action Amount

Question 34

Functional tolerance

Answer 34

1. Changes that reduce the reactivity to the drug at the sites of action 2. Mostly with psychoactive Reactivity

Question 35

Conditioned Drug Tolerance

Answer 35

Situations where tolerance effects are expressed only when the drug is administered in the same situation as before

Question 36

Seigel's Hypothesis

Answer 36

We are more vulnerable to an overdose in new contexts We build tolerance and start administering more of the drug - when the environment is changed, the tolerance is no longer present and overdose is more likely

Question 37

Conditioned stimuli

Answer 37

Environmental stimuli predicting regular use of the drug

Question 38

Exteroceptive stimuli

Answer 38

External stimuli e.g. the environment

Question 39

Interceptive stimuli

Answer 39

Internal stimuli e.g. thoughts (have been shown to evoke a conditioned response)

Question 40

Unconditional stimuli

Answer 40

The effects of the drug

Question 41

Conditioned compensatory responses

Answer 41

Conditional stimuli leads to opposite responses to the drug that would normally be seen (due to tolerance) Conditional stimuli predict greater 'conditioned compensatory responses' which counteract the natural (unconditioned) effects of the drug in the same situation, thus building situationally specific tolerance

Question 42

Conditioned Compensatory Responses vs Withdrawal

Answer 42

- Both produce almost identical, opposite effects to the unconditioned effect of the drug - Withdrawal - caused by not receiving the drug - CCR - caused by the body predicting the drug is coming through context cues?

Question 42

Conditioned Compensatory Responses vs Withdrawal

Answer 42

- Both produce almost identical, opposite effects to the unconditioned effect of the drug - Withdrawal - caused by not receiving the drug - CCR - caused by the body predicting the drug is coming through context cues?

Question 43

Theories about Addiction

Answer 43

Genetic influences Positive incentivisation theory

Question 44

Contingent Drug Tolerance

Answer 44

Tolerance develops only to drug effects that are actually experienced

Question 45

Genetic Influences (Gene for Acetaldehyde Dehydrogenase production)

Answer 45

Enzyme that controls alcohol metabolism Gene for less AD production = acetaldehyde is metabolized slower, effects like nausea, headaches, increased heart rate, flushed face etc. are more common - Less likely to develop alcoholism

Question 46

Incentive sensitization theory

Answer 46

- Dopamine release in the nucleus accumbens happens from craving the drug, not necessarily doing it - Incentive value goes up, hedonic value goes down - Pleasure goes down due to tolerance

Question 47

Positive incentive theory

Answer 47

Taking drugs to not feel the withdrawal effects

Question 48

3 Major Causes of Relapse

Answer 48

Stress: major factor in relapse e.g. nicotine Priming: a single exposure to a formerly abused drug (just once) Exposure to environmental cues: people, time, places or objects associated with drug taking