Psychoactive drugs Flashcards
What words are used interchangeable with hallucinogens ?
psychedelics and psychotomimetics
What are the clinical effect of hallucinogens ?
Somatic: dizziness, nausea, tremors
Perceptual: alter shapes, sharpened sense of hearing
Psychic: altered mood, distorted time sense, visual hallucinations
What are the two classes of hallucinogens chemical structures ?
- Tryptamines
- Phenethylamines
What are the two groups of hallucinogens with a tryptamine structure ?
- simple amines (DMT + psilocybin) flexible conformity
- Ergolines have ridgeid analoges (LSD)
How is cross tolerance show between mescaline and LSD?
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
What is the side effect from LSD which causes senses to get mixed up (experience colour as a sound)?
synaesthesia
What receptors do LSD interact with?
5-HT in the peripheral vasculature
Is LSD an agonist or antagonist to 5-HT?
agonist
How does LSD alter perception?
Decrease firing rate of raphe neurones (5-HT1A receptor)
What does Phencyclidine (PCP) do?
Causes catatonic like state
Same class as ketamine
Which receptors does PCP interact with?
Sigma opiate = modulates NAdr release
Non-competitive antagonist of NMDA (glutamate receptor)
Increase in dopaminergic neurones firing as PCP conc increases
What does NMDA inhibit?
Dopaminergic pathways/ subcortical activity
Which drugs act on catecholamine neurotransmission?
Cocaine and NMPH
How does cocaine impact presynaptic neurones?
catecholamine transported back into the neurones terminal via high affinity uptake. Cocaine blocks the high affinity uptake, increasing the catecholamine in synaptic cleft
What are the effects of cocaine?
- local anaesthetic (locks voltage-gated Na channels)
- euphoria
- appetite suppressant
- addictive properties
How does amphetamine (AMPH) work ?
AMPH transported into the neurones instead of DA (called reverse transport)
What is the net effect of MDMA
Increase 5-HT by decreasing 5-HT serotonin uptake and blocks MAO (responsible for metabolising NTs)
What is a possible long term effect of ecstasy?
degeneration of raphe neurones leading to reduction of 5-HT on the brain
Why do withdrawal symptoms occur ?
Opposite effect to those experienced in presence of the drug
Caused by maladaptive as a result of presence of drug
What does cocaine bind to?
binds with high affinity to monoamine, including dopamine transporters
What is involved in alcohol use disorder?
limbic system and dopamine signalling ( the VTA projections to the nucleus accumbent )
What do addictive drugs increase in the nucleus accumbens ?
Dopamine
How does dopamine signalling change due to addiction?
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
What is the net effect of opiates on DA?
increase in dopamine downstream
