Recreational Drugs Flashcards
Describe the reward pathway
A Dopaminergic pathway from ventral tegmental area to the nucleus accumbens
Dopamine neurons in the ventral tagmentum area are inhibited by the gabaergic inhibitory internueron
How does heroin act on the reward pathway?
Heroin removes the inhibition on the dopaminergic neurons in the VTA from the Gabaergic inhibitory interneurone therefore increasing the amount of dopamine in the synaptic cleft at the nucleus accumbens
How do you treat heroin adiction
Methadone maintenance - it has a long half life and is orally active
- stabilise and maintain
- stabilise and withdraw
Buprenorphine (+naloxone) - sublingual administration
safe controlled heroin supply
How does cocaine act on the dopaminergic pathway?
Blockade of dopamine re-uptake into nerve terminals in the nucleus accumbens
How does amphetamine and methamohetamine act on the dopaminergic pathway
Substrates for dopamine transporter
Blockade of re-uptake of dopamine
Inhibition of enzymic degradation of dopamine by MAO
Stimulates dopamine release.
Acute effects of amphetamine
Elevated mood Increased alertness Insomnia Increased stamina Anorexia Aggression Psychosis Increased heart rate Raised blood pressure
Post amphetamine effects (after effects of drug have worn off)
Fatigue Sedation Depression Dysphoria Psychiatric disorders Sustained raised BP
What is methamphetamine (crystal meth/speed)
a more potent amphetamine
What are the effects of methamphetamine?
Increased activity (includes sexual activity)
Reduced need for sleep (use in narcolepsy)
Decreased appetite
A general sense of well-being
how long does methamphetamine last?
6-8 hours
Side effects
After the initial rush there may be some violent behaviour
How does MDMA work?
Causes 5-HT release
Inhibits 5-HT re-uptake - substrate for the transporter
What drug can block the neurotoxicity of MDMA
Prosac
Effects of MDMA
Elevated mood Increased alertness Insomnia Increased stamina Perception disruption Increased body temperature Increased thirst 5-HT syndrome (excess serotonergic activity)
Post MDMA effects (after effects of drug have worn off)
Fatigue Sedation Depression Dysphoria Anxiety
Adverse effects of MDMA
Depletion of 5-HT neurons
Loss of the 5-HT transporter
What is the active ingredient in cannabis
Δ9- tetrahydrocannabinol (THC)
What receptors does THC in cannabis act on?
CB1 and CB2 receptors
what are the effects of cannabis?
Sedation Feeling of well being Perceptual change (e.g. time) Amnesia Lowered temperature Anti-emetic Appetite stimulation Analgesia
What are the potential therapuetic applications for cannabis
Reduce nausea Increase appetite (anorexia) Reduce intraoccular pressure in glaucoma Control muscle spams Treat mild to moderate pain
What are the long term effects of cannabis at a young age
high doses induce psychotic episodes
chronic use/early users have increased likelihood of developing schizophrenia (although it may increase the likleyhood of those already prone to getting it)
What CB1 receptor antagonist was used as an anti-obesity drug to reduce apetite?
Rimonabant
why was Rimonabant removed from the market?
It caused depression and suicidal thoughts
Give 4 examples of hallucinogens
LSD
PCP
Ketamine
Salvinorin
How does LSD work?
partial agonist at the 5-HT2c receptors
How does PCP/Ketamine work?
NMDA receptor channel blocker
How does Salvinorin work?
kappa opioid receptor agonist
what are the acute effects of hallucinogens?
altered sensations visual disturbances euphoria psychosis panic flashbacks
what are the post hallucinogen effects?
panic attacks
flashbacks
psychiatric disorders
Problems with ketamine use (acute and chronic)?
acute = GI cramps chronic = severe bladder pain
What receptor does nicotine act on
nicotinic acetylcholine receptors (nAChRs)
effects of smoking
Smokers weigh about 4kg less than non-smokers, due to reduced food intake
Psychological dependence, physical dependence and tolerance
Life expectancy shorter due to health defects such as lung cancer
Smoking during the latter half of pregnancy significantly reduces birth weight
What disease is smoking protective?
Parkinsons
what does ethanol act on?
Enhancement of both GABA- and glycine-mediated inhibition
Inhibition of Ca2+ entry through voltage-gated calcium channels
Activation of certain types of K+ channel
Inhibition of ionotropic glutamate receptor function
Inhibition of adenosine transport.
Adverse effects if ethanol
Aggressive behaviour Incoordination (driving) Neurotoxicity (chronic and binge drinking) Liver damage Impairment of fetal development
