nicotine Flashcards
(24 cards)
1
Q
what is tobacco
A
- requires sunny climate - china, india, idonesia, zimbabwe, brazil
- synthesised in root - accumulates in the leaves
- nicotine is a neurotoxin
- 0.0-3% is nicotine of the tobacco
2
Q
nicotine pharmacology
A
- cigarette cotains 6-11 mg of nicotine, only 1-3mg is absorbed
- nicotine attaches to tar molecules of cigarette smoke
- tar is acidic and making conditions more suitable for nicotine absorption
- absorption is fast and spiked within minutes
- arterial nicotine rose more rapidly and reached higher peak relative to venous blood, suggesting nicotine is rapdily delivered to target sites in the CNS
3
Q
how does cigarretes compare to oral and inhaling consumption
A
- rapid lung absoprtion
- direct arterial transport
- pure nicotine inhalators has to be extremely high in nicotine to have the same effects as cigarettes - not as effective
4
Q
neural mechanism in nicotine
A
- nicotine is an agonist at nicotinic acetylcholine receptors
- the neurotransmitter acetylcholine is a neuromodulator which can influence activity in target cells
- ACh plays an important role in learning and intellectual function, degeneration in this system is seen as alzheimers disease
- nicotine activates ACh neurons in the pedunculopontine nucleus
- these neurons excite dopamine-producing cells in the VTA - increasing dopamine in mesolimbic pathways
5
Q
evidence for dopamine activity in the VTA
A
- rats administered tobacco smoke
- dopamine activity was measured by microelectrode place in VTA
- increased activity observed following tobacco
- but reduced administration of nicotinic receptor antagonist
6
Q
nicotine self-administration experiment
A
- rats self administered nicotine directlty to VTA - nicotine has rewarding effects
- blocking dopamine receptors stopped administration - nicotine effects depend on dopamine
- nicotine stimulates ACh receptors - increases dopamine activity - increased activity mediates addictive properties
- blocking ACh receptors also stopped self administration
7
Q
susceptibility factors to nicotine
A
- nicotine metabolism - slower at metablosising needs fewer cigarettes less likely to become dependent
- adolescents - prone to being addicted - 18-25
8
Q
smoking in adolescent rats study
A
- rats given the opportunity to self-administer nicotine
- adolescent rats worked harder for nicotine and took larger amounts
9
Q
nicotine dependence
A
- 75.6% ever used, 24.1% history of dependence, 31.9% became dependent
- 60% of current smokers reach criteria for dependence
- 10% are long term low-rate smokers
- dependence is not inevitable
10
Q
withdrawal effects of nicotine
A
- urges and cravings
- irritated
- anxious
- restlessness
- concentration difficulties
- sleeping difficulties
- smokers adjust their cigarette use to maintain nicotine levels sufficient to avoid withdrawal effects
11
Q
when do lapses in nicotine occur
A
- long term cessation is challenging
- smokers who had just quit recorderd situations in which they lapsed in dairies
- almost 100% of lapses occurred when cigarettes were available and smoking was allowed
- these data suggests situational cues for drug availability play a critical role in maintaining drug use
12
Q
what is nicotine replacement therapy
A
- nicotine in alternative form
- alleviate withdrawal symptoms by maintaining ACh receptor occupancy
- may lead to transfer of dependency rather than completely eliminating nicotine
- anti-depressants - reduce negative emotional effects of withdrawal
- 12-month sustained abstinence rate increases to 5% from 2% using NRT
13
Q
how does nicotine test exposure models
A
- legal drug that is widely available
14
Q
what is habit-based accounts
A
- behaviour becomes automatic, triggered by cues, insensitive to outcomes
- stimulus-response theory
- incentive salience theory, attentional bias
- outcome devaluation studies
15
Q
what are goal-directed accounts
A
- behaviour is deliberate, based on expected value of outcomes
- expectancy theory
16
Q
what is reinforcement model
A
through associative learning, drug associated cues and contexts acquire the capacity to motivate drug seeking and taking behaviour
- addict as a machine, heaviour automatically controlled by external cues without any thought of consequences
- drug-induced dopamine activity reinforces the synaptic connection between drug cues and drug seeking response that produced the drug
- as a consequence of this change in synaptic strength, drug cues elicit the drug seeking response directly
17
Q
what is the outcome devaluation procedure
A
- phase 1 - instrumental training - rats are trained to press lever to receive food pellets
- phase 2 - outcome devaluation - rats are given free access to the same food until satiated
- phase 3 - extinction test - back in original context - press the lever but no food delivered
- if lever pressing decreases - behaviour is goal-directed - adjust based on current value
- if responding persists - behaviour has become habitual - insensitive to changes in outcome value
18
Q
what did Dickinson 1985 find about devaluation
A
- rats trained to press one lever for sucrose and one for alcohol
- one reward devalued via lithium chloride
- rats then tested in extinction - no rewards given
- found sucrose lever - pressing decreased - goal-directed
- alcohol lever - pressing unchanged - habitual
- food seeking involved expectation of outcome
- alcohol seeking was stimulus driven - insensitive to consequences
19
Q
what is incentive salience theory
A
- elaboration of habit theory
- proposes that drug cues acquire the capacity to capture attention - attentional bias
- attention results in engagement of thoughts about the drug and drug use which in turn cause drug users to initiate drug seeking
- addiction is driven not just by pleasure but by an intense motivation to seek drugs
- over time drug related cues become sensitized and triggers strong wanting, even if liking is reduced
- explains why people continue to seek drugs despite no longer enjoying them
20
Q
evidence for attentional bias
A
- simple target detection and change in detection tasks are easier for people who are drug dependent if image relates to drug use
- eye-tracking - eye gaze draw more easily to drug related cues
- stroop task - those with drug dependency are slower to name colour of drug related words
- greater stroop attentional bias is associated with poorer treatment outcome in those addicted to varous drugs
21
Q
expectancy theory - cravings
A
- habit theory is at odds with the role of conscious decision to drug seeking behaviour
- an urge or craving to smoke often accompanied relapse and drug use
- most addicts report that their drug seeking behaviour is undertaken intentionally
- a mental image of the drug, incorporating its perceived appetitive value, its stimulus characteristics, circumstances under which it might be obtained, behaviours required to obtain the drug
22
Q
what is the expectancy theory
A
- proposes that behaviour is goal directed
- pavlovian stimuli only elicit a conditioned response when they activate a mental representation of the expected outcome
- evidence in general human cognition
- drug conditioning demonstrated that expectancy awareness predicts drug seeking behaviour
23
Q
what did hogarth et al 2006 find about expectancy theory
A
- discriminative stimuli
- expectancy rating - how likely are you to win
- response - choose to seek or not
- outcome - win or lose cigarette
- found aware group recognised the association between specific cues and outcomes
- aware group - higher expectancy rating and seeking for positive stimuli
- unaware group - no change
24
Q
cognitive models
A
- if drug seeking was intentional, we’d expect a perfect correlation between craving and drug use behaviour
- but meta analysis of studies state that the correlation is far from perfect
- tiffany proposed that drug users can switch between intentional and automatic modes of behavioural control
