Psychoactive drugs

Question 1

What words are used interchangeable with hallucinogens ?

Answer 1

psychedelics and psychotomimetics

Question 2

What are the clinical effect of hallucinogens ?

Answer 2

Somatic: dizziness, nausea, tremors
Perceptual: alter shapes, sharpened sense of hearing
Psychic: altered mood, distorted time sense, visual hallucinations

Question 3

What are the two classes of hallucinogens chemical structures ?

Answer 3

1. Tryptamines
2. Phenethylamines

Question 4

What are the two groups of hallucinogens with a tryptamine structure ?

Answer 4

1. simple amines (DMT + psilocybin) flexible conformity
2. Ergolines have ridgeid analoges (LSD)

Question 5

How is cross tolerance show between mescaline and LSD?

Answer 5

If person gains tolerance to mescaline due to taking it often = tolerant to LSD although naive to taking it
Shows they act on the same class of receptor sites
Both similar structure of 5-HT

Question 6

What is the side effect from LSD which causes senses to get mixed up (experience colour as a sound)?

Answer 6

synaesthesia

Question 7

What receptors do LSD interact with?

Answer 7

5-HT in the peripheral vasculature

Question 8

Is LSD an agonist or antagonist to 5-HT?

Answer 8

agonist

Question 9

How does LSD alter perception?

Answer 9

Decrease firing rate of raphe neurones (5-HT1A receptor)

Question 10

What does Phencyclidine (PCP) do?

Answer 10

Causes catatonic like state
Same class as ketamine

Question 11

Which receptors does PCP interact with?

Answer 11

Sigma opiate = modulates NAdr release
Non-competitive antagonist of NMDA (glutamate receptor)
Increase in dopaminergic neurones firing as PCP conc increases

Question 12

What does NMDA inhibit?

Answer 12

Dopaminergic pathways/ subcortical activity

Question 13

Which drugs act on catecholamine neurotransmission?

Answer 13

Cocaine and NMPH

Question 14

How does cocaine impact presynaptic neurones?

Answer 14

catecholamine transported back into the neurones terminal via high affinity uptake. Cocaine blocks the high affinity uptake, increasing the catecholamine in synaptic cleft

Question 15

What are the effects of cocaine?

Answer 15

• local anaesthetic (locks voltage-gated Na channels)
• euphoria
• appetite suppressant
• addictive properties

Question 16

How does amphetamine (AMPH) work ?

Answer 16

AMPH transported into the neurones instead of DA (called reverse transport)

Question 17

What is the net effect of MDMA

Answer 17

Increase 5-HT by decreasing 5-HT serotonin uptake and blocks MAO (responsible for metabolising NTs)

Question 18

What is a possible long term effect of ecstasy?

Answer 18

degeneration of raphe neurones leading to reduction of 5-HT on the brain

Question 19

Why do withdrawal symptoms occur ?

Answer 19

Opposite effect to those experienced in presence of the drug
Caused by maladaptive as a result of presence of drug

Question 20

What does cocaine bind to?

Answer 20

binds with high affinity to monoamine, including dopamine transporters

Question 21

What is involved in alcohol use disorder?

Answer 21

limbic system and dopamine signalling ( the VTA projections to the nucleus accumbent )

Question 22

What do addictive drugs increase in the nucleus accumbens ?

Answer 22

Dopamine

Question 23

How does dopamine signalling change due to addiction?

Answer 23

Dopamine receptors are lower in cocaine abusers = continued elevated levels of dopamine leads to down regulation of DA r to restore level of signalling in the circuits.
= maladapted, compromised reward system

Question 24

What is the net effect of opiates on DA?

Answer 24

increase in dopamine downstream