Nicotine; Caffeine Flashcards
Plant of nicotine
Produced in plants of the nightshade family: insecticide properties
Nicotiana tabacum is most commonly cultivated
Juul and modern vaporizers
Nicotine salts (protonated nicotine) Earlier nicotine peak Tremendously potent
Tobacco use/exposure: Increased rates of cancer due to
nitrosamines in tobacco smoke
Tobacco use/exposure: Increased rates of
cancer, cardiovascular disease (CVD), pulmonary disease (Emphysema), pregnancy complications
Tobacco use/exposure: Teratogen
Increased pregnancy complications: malformation of embryo
First, second, third hand smoke
First - smoking
Second - through air
Third hand (smoke adhered to objects)
All convey risks
History of tobacco use
Mayans, incas, Toltecs, aztecs - religious purposes
First introduced to europe in 15th century. Mid 16th century = widespread
An important trade crop
Questions about safety date to early 17th century
The early 20th century saw researchers focus on adverse effects
Absorption of nicotine
Absorbed via mouth, nose, throat, lungs
Inhalation = most effective for nicotine delivery - exception: e-cigs
Peak absorption: 5-7 min for cigarettes (lungs)
20-30 Min for most other products
Biotransformation and elimination of nicotine
Blood brain barrier
Nicotine readily crosses blood-brain barrier
Biotransformation and elimination of nicotine
Metabolization
In liver
Active metabolite: cotinine
Mentholation slows metabolism (menthols)
Polymorphisms can affect rate of metabolism
Slower metabolizers are more likely to be light smokers
Half life nicotine
Half-life of nicotine: 2 hours (Less for chronic smokers)
Cotinine: 17 hours
Eliminated via urine
Nicotine agonist or antagonist?
Nicotine is a cholinergic agonist (increases the function of receptor)
What receptor does nicotine bind to?
nicotinic receptors = nAChRs acetylcholine receptors
Ionotropic receptors
When nicotine binds to acetylcholine receptors it creates an excitatory or inhibitory post synaptic potential?
EPSP
Nicotinic receptor desensitization
Desensitized state - Functional antagonism: high binding affinity - stays for a long time. Channel closes, molecule stays = blocks it in the long term. Becomes an antagonist.
Upregulation (acute tolerance) - first cigarette of the day feels better than second
Distribution of nicotinic receptors (AChRs)
Peripheral nervous system
Neuromuscular junction
Ganglia of autonomic nervous system
Distribution of nicotinic (AChRs) receptors
Central nervous system
Hippocampus and cerebral cortex
Basal ganglia
Ventral tegmental area (projecting to) nucleus accumbens (and other areas)
Rewarding (addictive) properties of nicotine
Indirect dopamine release
Nicotine receptors activated in the VTA or NA increase dopamine release in NA
Other constituents of tobacco enhance effects