Nicotine Flashcards
Nicotine
The main psychoactive ingredient in the tobbaco plant (Nicotiana tabacum). Nicotine is a natural insecticide developed by tobacco plants as a defence mechanism.
Many indigenous peoples used tobacco for ___
spiritual and religious purposes.
Tobacco was first introduced to Europe in the [answer] century.
15th
By which century was use of tobacco across Europe widespread?
16th century (1500s)
As early as the [answer] century, there were questions about the safety of tobacco.
17th
The [early or late] [answer] century saw researchers focus on the adverse effects of tobacco.
early 20th century
Cigarettes
Definition, nicotine content, nicotine bioavailability
Most commonly used tobacco product. A tobacco blend rolled in a sheet of paper, often has a filter at the end to reduce the amount of tobacco tar being inhaled.
Contains 6-11mgs of nicotine, 1-2mgs of which are bioavailable.
Cigars
Definition, nicotine content
Rolled bundles of dried tobacco leaves.
Hard to define nicotine content, but can contain up to 335 mgs of nicotine.
Pipes/Hookahs (water pipes)
Usage
Pipes are utilized for inhaling tobacco blends (often have water pipes/pass through containers of water). Used in the Middle East for centuries.
Smokeless tobacco
Eg. Chewing tobacco. Can be absorbed through the mouth/mucus membranes.
Vaporizers/E-cigarrettes
‘Replacement therapy’ where nicotine is isolated and heated, to reduce the amount of tar consumed when smoking.
Juuls/Vapes/Vaping
A type of e-cigarette that uses nicotine salts (nicotine converted to salt form). Reduces the “burn” that comes with smoking. However, these salts have a quicker nicotine peak and are much more potent.
Very popular amongst teenagers and young adults. Billion dollar tobacco business.
Four risks tobacco use/exposure can increase
- Rates of cancer
- Rates of cardiovascular disease (CVD)
- Rates of pulmonary disease
- Rates of pregnancy complications
Effects oral health as well.
Emphysema
Causes significant shortness of breath. Transfer of O2 and CO2 in the lungs is more difficult/decreased.
Nitrosamines
A main class of carcinogenic compounds found in tobacco smoke. Eg. tar
Teratogens
Something that can cause physiological abnormalities in an embryo.
First-hand, second-hand and third-hand smoke
First-hand smoke: Someone themselves smoking.
Second-hand smoke: Breathing in the smoke of someone smoking.
Third-hand smoke: Breathing in remnants of tobacco smoke that gather on the material of the smoker’s environment.
Fewer risks with non-tobacco products, but still risky, and not studied as much, especially in the long-term.
Nicotine can be absorbed through:
The mouth, nose, throat, lungs
What method is most effective for nicotine delivery?
The exception being most e-cigarettes
Inhalation
Peak concentration after smoking a cigarette (lungs)
5-7 mins
Peak concentration after consuming tobacco through most products besides cigarettes
20-30 mins
Nicotine is metabolized by which organ?
The liver
What is nicotine’s active metabolite?
Cotinine
Mentholation
Slows the metabolism of nicotine
With nicotine, genomic [answer] affect the rate of metabolism
polymorphisms
Slower metabolism of nicotine = less likely to get addicted
Nicotine is a [answer] partial [agonist/antagonist], at [answer] receptors.
Nicotine is a cholinergic (as in affects acetylcholine) partial agonist at nicotinic receptors
(nAChRs),
Nicotinic receptors have five different subunits.
Are nicotinic receptors ionotropic or metabotropic?
Ionotropic
Distribution of Nicotinic Receptors (nAChRs)
Found in peripheral nervous system:
* Neuromuscular junction
* Ganglia of autonomic nervous system (first time users may start sweating due to activation of sweat glands, feel sick, etc.)
Found in central nervous system:
* Hippocampus and cerebral cortex
* Basal ganglia
* Ventral tegmental area and nucleus accumbens
The three ways nicotine effects dopamine release
Nicotine receptors activated in the ventral tegmental area (VTA) send signals to the nucleus accumbens (NAcc) to release dopamine. As well, when nicotine binds to heteroreceptors (pre-synaptic release modulators) on the terminal region of a VTA neuron, it enhances the dopamine release. It also inhibits MAOI (monoamine oxidase) which also enhances the effects of dopamine as it slows the metabolism of dopamine.
TL;DR/Key Points:
1. Receptors tell VTA to tell NA to release dopamine
2. On terminal of axons in VTA dopamine release is inhanced by dopamine
3. Nicotine inhibits MAOI
Acute tolerance with nicotine/how it works
Nicotine can cause acute tolerance. There is often upregulation with nicotinic receptors (increased receptor numbers). As well, due to desensitization, ion channels may start staying closed even if nicotine is attached, thus nicotine in a way starts acting as a “functional antagonist.” These both are mechanisms to counteract usage of nicotine after it’s used at least once during the day. Thus, people get less of a “hit” each time they smoke throughout the day due to the build-up of tolerance.
Half-life of nicotine
2 hours (shorter in chronic smokers)
Half-life of continine
17 hours
Physiological effects of nicotine
- Sympathomimetic effects (activates the sympathetic nervous system, speeds up heart rate, raises blood pressure, etc.)
- Cognition and movement (stabilizes movement, cognitive enhancer/attention)… but don’t forget, the enhancement only works until tolerance is built
- Reduces appetite/appetite suppressant (also a sympathomimetic effect)
Naïve (first time) users of cigarrettes report what effects vs. habitual smokers?
Naïve users report negative subjective effects. Habitual users report positive subjective effects, and have built tolerance to negative subjective effects.
Chippers
- Similar to social smokers
- Resistant to addictive effects of nicotine like withdrawal
- Surprisingly common
- There are genetic and environmental mechanisms affecting them
The one exception to habitual smokers becoming addicted to smoking!
Nicotine
The “magic timeframe” after which withdrawal symptoms have diminished
2 weeks
Nicotine replacement therapy
Eg. Gum, patches, nasal spray, vapes
Which antidepressant is used to treat nicotine addiction?
Buproprion, an NDRI and nAChR antagonist
Buproprion is considered an atypical antidepressant.
Better rates of abstinence in:
Women or men?
Which ethnicity?
Which socioeconomic status?
Men, European Americans, higher socioeconomic status
Groups don’t usually achieve higher than a [X]% quitting rate in studies about smoking/tobacco/nicotine.
50%
Smoking is very hard to quit.
