Nicotine and tobacco Flashcards
impacts of smoke-free laws and policies (2)
- ~7% decrease in tobacco use
- dramatic reduction of second-hand smoke exposure
prevalence of smoking in canada
daily -> 8%
daily + non-daily -> 12%
short-term effects of tobacco use (8)
- euphoria (the high)
- enhances cognition (ex. attention)
- decreases appetite
- stimulates nausea and vomit reflex
- increases HR, breathing rate and BP
- CO blocks O2 from getting into bloodstream
- bad breath
- stimulates reward system and other neurochemical systems
systems that tobacco stimulates and what they’re involved in (7)
- DA -> pleasure, reward
- NE -> arousal, appetite suppression
- ACh -> arousal, cognitive enhancement
- Glu -> learning, memory enhancement
- b-endorphin -> reduction of anxiety and tension
- GABA -> reduction of anxiety and tension
- 5-HT -> mood modulation, appetite suppression
long-term effects of tobacco use (7)
- bronchitis and emphysema
- chronic obstructive pulmonary disease (COPD)
- heart and artery disease
- cancer (lung, bladder, pancreas)
- diabetes
- osteoporosis
- tobacco addiction
people who smoke die how many years earlier than non-smokers
13-14 years earlier
risk factors for tobacco use disorder (11)
- genetic predisposition
- parental exposure
- lower socioeconomic status
- peer pressure
- poor academic performance
- impulsivity
- low self-esteem
- mood disorders
- mental illness
- substance abuse
- onset of tobacco smoking during childhood or adolescence
long-term effects of /adolescent/ tobacco use (4)
- alters trajectory of normal brain development
- diminished cognitive function that persists into adulthood
- greater mental health problems
- effects that last into adulthood
how does adolescent tobacco use alter trajectory of normal brain development (5)
- dendritic remodelling
- lower GMV in thalamus and amygdala
- aberrant functional connectivity
- changes in reward system
- changes in 5-HT synaptic function
how does adolescent tobacco use diminish cognitive function (3)
- reduced attention span
- poorer memory
- enhanced impulsivity and lower inhibitory control
how does adolescent tobacco use cause greater mental health problems (2)
- increased anxiety, psychosis and depressive-like behaviors in adults
- more severe tobacco addiction later in life
what is nicotine (3)
- stimulant
- primary psychoactive constituent of tobacco
- underlies addictive properties
mode of delivery of nicotine: cigarette (4)
- nicotine is distilled from tobacco and carried in smoke particles into lungs
- moves quickly to brain (10-15s) -> faster than via IV
- binds to nAChR
- onset of CNS action within seconds
properties of nAChR (7)
- ligand-gated ion channel
- key role in modulating neuronal excitability
- regulates flow of cations across cell membrane
- 5 distinct membrane-spanning subunits (a and b) combine to form functional receptor
- each composed of various combinations of a/b subunits
- expressed pre-synaptically
- activated by nicotine and ACh
most abundant nAChR in brain (2)
a4b2 and a7
affinity of nicotine for a4b2 and a7
highest affinity for a4b2; low affinity for a7
brain areas with highest density of nAChRs (9)
- cortex
- hippocampus
- amygdala
- NAcc
- caudate, putamen
- VTA
- cerebellum
- thalamus
- insula
mechanism of nicotine/ACh binding to nAChR (4)
- binding induces conformational change
- cations flow through intrinsic channel -> depolarization of neuron
- after activation, nAChR become desensitized: channels close and receptor cannot be reactivated
- eventually regain sensitivity and become reactivated
how does nAChR desensitization influence effects of nicotine
limits duration of acute effects
desensitized nAChRs (3)
- still have high affinity for ACh and nicotine
- receptor is inactive -> binding has no effect
- decreased receptor responsiveness for subsequent stimulus
effect of chronic nicotine use on nAChR desensitized state
nAChR spend more time in desensitized state, causing an upregulation of nAChRs
effect of decreased nAChR responsiveness (2)
- acute tolerance of nicotine
- reduced satisfaction
upregulation of nAChRs due to chronic nicotine use (3)
- results from frequent desensitization of receptors
- compensation mechanism to augment nAChR response
- may contribute to difficulties with tobacco cessation
upregulation of nAChRs documented in (3)
- animal studies after chronic nicotine exposure
- postmortem tobacco smokers compared to non-smokers
- increased densities in striatum, cerebellum and cortex of living human smokers compared to non-smokers