Lecture 20 Flashcards
Drugs of recreation and addiction (21 cards)
Why is the mesolimbic dopamine system important in addiction?
• It mediates reward and motivation
• All addictive drugs increase dopamine in the nucleus accumbens
• Chronic use causes neuroadaptive changes, giving the drugs motivation salience and increasing drug-seeking behaviour
What type of drug is heroin?
Opioid
What is the history and use of heroin?
• Synthesised by Bayer as a cough suppressant and morphine alternative
• Rapid brain entry → intense euphoria
• Now illegal and highly addictive
What are the pharmacological effects of heroin?
• Analgesia, euphoria, sedation
• Respiratory depression (cause of death)
• Tolerance and dependence
What is the mechanism of action of heroin?
• Converted to morphine → activates μ-opioid receptors
• Inhibits neurotransmitter release via ↓ Ca²⁺ influx and ↑ K⁺ efflux
• Suppresses respiratory centres in the brainstem
What type of drug is cocaine?
Psychostimulant
What is the history and use of cocaine?
• Derived from coca leaves; used in Coca-Cola and as a local anaesthetic
• Popular recreational stimulant
What are the pharmacological effects of cocaine?
• Euphoria, increased alertness, appetite suppression
• Increased HR and BP
• Repeated use → psychosis, heart damage, stroke
What is the mechanism of action of cocaine?
• Blocks dopamine, noradrenaline, and serotonin reuptake transporters
• Increases synaptic dopamine → activates reward pathways
What type of drug is MDMA?
Psychostimulant
What is the history and use of MDMA?
• Synthesised by Merck (1912); popularised in psychotherapy and rave culture
• Known for “loved-up” effects
What are the pharmacological effects of MDMA?
• Euphoria, empathy, increased sociability
• Hyperthermia, insomnia, teeth clenching
• Risk of serotonin syndrome (increased activity) and seizures
What is the mechanism of action of MDMA?
• Reverses serotonin transporter → massive 5-HT release
• Inhibits 5-HT reuptake and breakdown
• Increases oxytocin levels
What type of drug is LSD?
Psychedelic
What is the history and use of LSD?
• Synthesised by Albert Hofmann (1938); discovered effects accidentally
• Used recreationally and in psychedelic therapy
What are the pharmacological effects of LSD?
• Hallucinations, synaesthesia, altered time perception
• Mood lability, psychosis-like symptoms
• Long-lasting (10–12 hours)
What is the mechanism of action of LSD?
• Partial agonist at 5-HT2A receptors (hallucinogenic effects)
• Also binds 5-HT1, 5-HT2C, dopamine, and adrenergic receptors
What is the history and use of cannabis?
• Most widely used illicit drug in Australia
• Used recreationally and medicinally (e.g., pain, anxiety, epilepsy)
What type of drug is cannabis?
Cannabinoid
What are the pharmacological effects of cannabis?
• Euphoria, appetite stimulation, analgesia
• Anxiety, memory impairment, sedation
• Schizophrenia risk, addiction
What is the mechanism of action of THC?
• Partial agonist at CB1 and CB2 receptors
• Inhibits neurotransmitter release via ↓ Ca²⁺ influx and ↑ K⁺ efflux
• Acts via retrograde signalling
