hallucinogens 2

Question 1

what do indoleamine and phenethylamine hallucinogens activate and what does this cause?

Answer 1

• activate serotonin receptors
• primary neuropharmacological mechanism = stimulation of 5HT receptors
• stimulation/activation of 5HT receptors = main contributor to psychological effects

Question 2

what are the two main groups of classical hallucinogens (in terms of chemical structure)

Answer 2

• phenethylamines
• indoleamines

Question 3

what does the serotonergic raphe in the midbrain do?

Answer 3

• supply large parts of the brain with nerves

Question 4

what type of receptors are 5HT2A receptors and what effect does activation do?

Answer 4

• G protein-coupled receptors
• stimulatory effects on the neurone (increases transmitter release and increased activity)
• may stimulate excitatory neurones including prefrontal cortex
• stimulating excitatory neurones may be critical for hallucinogenic effects

Question 5

what have animal studied shown about behavioural effects of classical hallucinogens?

Answer 5

• shown that classical hallucinogens = blocked by selective 5HT2A receptor antagonist

Question 6

what does MDMA stimulate?

Answer 6

serotonin release

dopamine release (including nucleus accumbens)

Question 7

what is the primary neuropharmacological mechanism of dissociative anaesthetics?

Answer 7

• blockade of channel pore of NDMA-type glutamate receptor
• this increases neural excitation in many brain areas by disinhibition (reducing activity of inhibitory neurones)

Question 8

what else does NMDA receptor antagonists stimulate?

Answer 8

• prefrontal cortex
• nucleus accumbens dopamine release
• this may be regulated by increased neural excitation in cortical regions

Question 9

identify adverse effects of dissociative anaesthetics and MDMA

Answer 9

• dependence
• neurodegeneration
• ketamine bladder

Question 10

explain dependence as an adverse effect of dissociative anaesthetics and MDMA

Answer 10

• animal studies show evidence that support dissociative anaesthetics and MDMA can cause dependence
• potential for dependence = lower than other drugs of abuse

Question 11

explain neurodegeneration as an adverse effect of dissociative anaesthetics and MDMA

Answer 11

• studies in animals shown that non-competitive NDMA receptor antagonists, including PCP and ketamine and MDMA cause neurodegeneration
• induced neurodegeneration = selective to serotonergic neurones
• for MDMA = no compelling evidence than recreational use of drug also damages serotonergic neurones in humans

Question 12

explain ketamine bladder as an adverse effect of dissociative anaesthetics and MDMA

Answer 12

• thickening of bladder
• lower bladder capacity
• kidney dysfunction
• k-cramps
• all reported in chronic ketamine users

Question 13

explain how classical hallucinogens/MDMA are used in assisted psychotherapy

Answer 13

• drug used in 1 or few occasions
• used to overcome obstacles for successful psychotherapy
• used to treat substance abuse, severe depression, cancer anxiety, PTSD, alcohol-dependence
• needs careful clinical supervision due to potential ‘bad trip’