Week 7 : Tobacco and Vaping Flashcards
Basics of Tobacco
Only known natural source of nicotine
The plant belongs to the nightshade family (Solanaceae)
Nicontiana tabacum is cultivated widely all over the world
Originally cultivated and used in North and South America
History of Tobacco
- Tobacco originates in south and north america. The spanish colonists were then given tobacco from the south American natives
- Jean Nicot - a French Ambassador to Portugal became convinced of the medical usefulness of the tobacco plant
Presented the tobacco plant to the French royal family
The genus Nicotiana was named after him
Tobacco was widely used for “medicinal” purposes (eg. to help bruises)
- The English were among the last to take up smoking
By the end of the 16th century, the demand for tobacco began to worry some
In 1604 King James I published A Counterblaste to Tobacco
Refuted claims for medical benefits of smoking
This early work anticipated many of the modern criticisms of smoking
King James 1 On Smoking
It affects the “inward parts of men, soiling and infecting them, with an unctuous and oily kind of Soote, as hath bene found in some great Tobacco takers, that after their death were opened”.
Tobacco in North America
Colonists began cultivating tobacco in a last effort before quitting
Hugely successful
By 1720, Virginia tobacco was the primary source for England
Primary reason for slave labour in North America
Smoking and Snuffing and chewing
Smoking had been the most popular method of tobacco use in Europe
Snuffing was popular for a time, particularly among clergy
Not outlawed in churches
Easy to hide from disapproving parishioners
Tobacco chewing was an American export
First observed as a habit of native people
Never popular in Europe
Following the Revolutionary War, the new United States deliberately rejected European habits and fashions
Snuff was rejected, tobacco chewing was adopted with patriotic zeal
Chewing was democratic, snuff was aristocratic
Westward expansion brought chewing tobacco with it
Baseball players use of chewing tobacco popularized it
Still common today
Cigarettes
Early explorers noted that “Mexican Indians” smoked tobacco through reeds
A small percentage of people in Spain and Portugal smoked cigarettes throughout the next couple of centuries
In 1840, cigarette smoking become very popular in France
– Mostly among French ladies
– Enthusiasm women showed led to general acceptance
About the same time in North Carolina, flue-cured, or “bright” tobacco was discovered
Stephen, a slave on the plantation of Abisha Slade, credited with discovery
Heat cured with charcoal, rather than smoked
More mild taste and aroma, perfect for cigarettes
Perfect for arid, infertile soil
Cigarette smoking skyrocketed
Smoking in the 60’s and 70’s
In 1964, the US Surgeon General’s Report linked smoking to cancer and other diseases
In 1971, the Royal College of Physicians of London published a similar report
Smoking has declined among adults in developed nations
Smoking has increased dramatically in developing nations
During this time there was a rapid increase in cig smoking in developing countries but it plateud in industrial countries
By the mid 2020’s around …. of smokers will be in developing countries
85%
Neurophysiology of Smoking/vaping aka nicotine
*Nicotine acts on the nicotinic acetylcholine receptor (nAChR)
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*Located in both PNS and CNS
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*In the PNS, they are located at neuromuscular junctions and control voluntary muscle action
*Blocked by curare, a poison used on dart and arrow tips by some South American tribes
*Blocks the ability of nerves to cause muscle contractions
*Causes paralysis and death by asphyxiation (diaphragm can’t function)
Self-administration of cigarettes in nonhumans
- people argue about what the addictive aspect of cigarettes are as unlike with many addictive substances, non-humans don’t self administer them
it is notoriously difficult to get lab animals to self-administer nicotine
*Some question whether nicotine is a reinforcer at all
*Very narrow range of reinforcing doses
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*Presence of conditioned stimuli that have been paired with nicotine is critical
Dual reinforcement model
*Proposed by Caggiula and colleagues
*Suggests that nicotine
1. is a primary reinforcer
2.enhances the reinforcing value of other stimuli
Other components of cigarettes besides nicotine contribute to addiction - Brennan et al., 2015
*Brennan et al. (2015)
*Tested whether rats found nicotine, cigarette tobacco particulate matter, or roll-your-own particulate matter more reinforcing
*Used a self administration and progressive ratio paradigm
*Nicotine = TPM < Roll your own
*iNcotine by itself does not support a lot of behaviour
*It’s probably not that reinforcing
*Nicotine is mixed in with a lot of other ingredients in cigarettes
*Could these other aspects contribute to tobacco addiction?
*Roll your own tobacco has a higher proportion of MAO inhibitors
*Inhibit the breakdown of monoamine neurotransmitters, including dopamine
*More MAOIs, more dopamine
Besheer et al. (2004) - nicotine and conditioned responses
*Two treatment conditions
*Saline
*Nicotine
*Rats received free sucrose presentations when nicotine was on board
*No rewards when injected with saline
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*Will rats learn a conditioned response during nicotine sessions?
Bauld et al. (2017)
*Surveyed over 60,000 youth ages 11-16 for cigarette and e-cigarette use
*Included 3 different group designations
*Never smoked
*Ever smoked
*Regular smoked (weekly)
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*Never e-cigarette use
*Ever e-cigarette use
*Regular e-cigarette use (weekly)
Regular smokers and have smoked = higher vaping rates
those who have ever vaped = higher risk for smoking
BUT the people who smoke are more likely to vape at a greater level than those who vape to then smoke (so vaping is not likely causing smoking!)
What nicotinereceptors are most studied and widely spread throughout the brain ?
A7 and A4B2
