Drugs week 2 Flashcards
explain the biological basis of how drugs work on the brain
drug is introduced = upset the balance, brain will seek to gain homeostasis through neuroadaptation.
agonist vs antagonist neurotransmitters.
agonist: activate receptors (e.g. by mimicking a neurotransmitter or by increasing the existing neurotransmitter)
antagonist : block the activation of receptors
how does the brain try and maintain homeostasis.
downregulation: cellular decrease in number of receptors to brain chemicals
upregulation: increase in number of receptors on surface of target cells
What are the three biological process of tolerance
metabolic tolerance (pharmacokintetic) - body becomes better at breaking down the drug
alcohol:; amount of liver enzyme produced by body goes up
cellular tolerance (pharmacodynamic) : change in number of receptors
Explain caffeine’s role on the brain
Works on adenosine (neurotransmitter for sleep) as an antagonist (blocks activation of receptors) also blocks GABA (circadian rhythm, at high dose)
- upregulation of A1 adenosine receptors, serotonin receptors and GABAa receptors.
explain the role of caffeine in society
- psychoactive substance
-added to 70% of non-alcoholic ‘soft drinks’ - mainly through coffee and tea.
- placebo vs caffeine = higher tolerance in caffeine.
explain the role of nicotine on the brain
agonist (activates receptors) effect on acetylcholine transmitter (arousal, motivation, learning), stimulates nicotinic receptors of acetylcholine neurons.
explain the role of alcohol on the body
- acts on multiple neurotransmitters
- effects : sedation, relaxation, euphoria
- crosses bbb very quickly
- non-specific: acts as depressant on all brain neurons
- disturbs neuronal membrane lipids - membrane fluidization.
explain the specific role of alcohol on the brain
- inhibits glutamate (memory, emotions, sensory information, motor coordination)
-by reducing effectiveness at NMDA glutamate receptor
-enhances endorphin activity in the dopaminergic reward pathway, leads to disinhibition of dopamine release in the nucleus accumbens.
explain the role of sugar and alcohol
- increased intake of alcohol when denied access to sugar
- access to alcohol increased sugar intake in rats
bingeing on either sugar or alcohol fostered intake of the other - bidirectional relationship
explain the role of cannbis on the body
depends on individual and species of plant
relaxation, happiness, increased laughter, chattiness, lack of motivation nausea, anxiety, confusion
THC :psychoactive
CBD: legal in the uk
how does cannabis work on the brain?
cannabinoid receptors react to THC and other cannabinoids
decreases GABA release, leads to an increase in synaptic dopamine levels.
Explain reasons why cannbis may have become legalised.
- Adverse health effects from cannabis are
modest in relation to other legal and illicit
drugs - Criminal penalties for cannabis are harmful for
users and the community, and outweigh the
negative consequences from use of the drug - If legal, cannabis can be better regulated and
taxed
27 - Chiu et al (2022) : more liberal attitudes across most demographic groups
explain the medical use and risk for cannabis
- good evidence for chronic pain, neurpathic pain and spasticity
- small risk for psychosis
- mixed evidence that could be carcinogenic
- addiction and gateway risk.
Explain the role of synthetic cannabinoids
- spice
- different effects on different receptors
- Full CB1 agonist
- Lack of CBD prevents calming effects
what are the effects of heroin and other opioids
addictive, relaxation, euphoria, sleepiness, happiness, less sensitive to pain and trauma, similar to endocannabinoids, heroin and morphine mimic endorphins, sit in the receptor sites of endogenous opioids. Synaptic dopaminergic neurons (involved in the reward mechanisms.
explain the tolerance of heroin
quick tolerance to nausea, no tolerance ever to constipation or pinpoint pupils
cross tolerance : once tolerant you are also tolerant to morphine, codeine and methadone.
whats the link between tolerance of heroin and overdosing?
- occurs when in recovery
tolerance goes down - individuals use habitual amount leading to overdosing.
what are the effects of cocaine
- confidence, euphoria, alertness, energy and excitement
how does cocaine work on the brain
- blocks the reuptake of dopamine, noradrenalin and serotonin
- acts as an agonist
- addiction due to increased dopaminergic activity in the mesocrotibcolimbic pathway
what are the effects of amphetamines
high energy, excitments and chattiness
DA agonist, stimulate release of noradrenlaine
why is MDMA not a psychostimulant
related as it also effects levels of dopamine and noradrneline but also hashalluconogenic effects
what are the effects and symptoms of MDMA
extreme happiness, energy and feelings of love, stimulates release of noradrenaline - agonist
stimulate release of serotonin 5HT
stimulate dopamine
what has new research suggested about therapeutic use of MDMA and other psychedelics
MDMA: alcohol dependence, PTSD, social anxiety in autism
Psychedelic research: Anxiety, depression, substance misuse
Licenced in 2023 in Australia MDMA = PTSD and Psilocybin for treatment resistant depression.
How does ketamine work on the body
acts of CNS - local anaesthetic properties
antagonist of NMDA
reduces presynaptic releases of glutamate
can be used as antidepressant.
explain how benzodiazepines work
- prescription medication with addictive properties.
- agonist for GABA, leading to muscles relaxant action
also blocks adenosine reuptake, decreasing arousal and increasing sleepiness.
What is addiction in simple terms?
chronically relapsing disorder that involves: compulsion to seek and take particular drug, loss of control in terms of limiting intake, negative emotional state when access to drug is prevented.
physical or psychological or both.
explain what is meant by physical withdrawal syndrome
- due to neuroadaptation
- drug wears off- uncomfortable symptoms occur
- reverse by administering drug (negative reinforcement)
explain the withdrawal timeline for opiates
10/24 hours= vomit
36/48 hours = sweating, nausea, runny nose, dilated pupils
48/72 hours = anxiety, insomnia, localized pain
72 hours/week= all symptoms gradually fade away
explain how withdrawal work in terms of addiction
- shorter half life= shorter withdrawal syndrome
- start to disccoiation between physical and psychological symptoms - evidence for craving after physical symptoms have gone
what is conditioned withdrawal
- pairing of CS with withdrawal leads to CR later, CS alone can induce withdrawal
what is addiction according to the DSM-5
11 different criteria for substance use disorder.
- one being craving and urgers to use the substance.
- 2/3 = mild
- 4/5 = moderate
- 6 or more = severe
- does not have to include to two physiological symptoms.
what is the ICD-11 criteria for substance misuse
must have two or more :
1. impaired control over substance use
2. substance use becomes an increasing priority
3. physiological features
explain the addiction cycle
- preoccupation/ anticipation (cues, small dose, stressor)
- binge/intoxication (positive reinforcement)
- withdrawal (uncomfortable physiological or psychological)
