Tobacco and Nicotine Addiction

Adapted from a presentation by George Sanchez, 4th year Biomedical Science major, Texas A&M University

Method of Delivery

• Tobacco products include cigarettes, cigars, and pipe tobacco, which are smoked; snuff, which is inhaled into the nose; and chewing tobacco, which is chewed but not swallowed.

• Inhalation of tobacco smoke is the fastest and most efficient way yet discovered to deliver nicotine to the brain.

History of Tobacco

• Tobacco was first used by the peoples of the pre-Columbian Americas.

• Native Americans apparently cultivated the plant and smoked it in pipes for medicinal and ceremonial purposes.

Tobacco Spreads to Europe

Adventurers like Jean Nicot of France (where

nicotine derives its name) popularize tobacco

mid 1500’s1556

Tobacco introduced to

France

Tobacco introduced to

Portugal

Tobacco introduced to

Spain

Tobacco introduced to

England

15581559

1565

Tobacco in the Colonies

• The first successful commercial crop was cultivated in Virginia in 1612 by Englishman John Rolfe.

• Within seven years, it was the colony's largest export.

• Over the next two centuries, the growth of tobacco as a cash crop fueled the demand in North America for slave labor.

Early Discoveries of the Effects of Smoking:

The 20th Century

• In 1930, researchers in Cologne, Germany, noticed that many cancer patients were smokers.

• Eight years later, Dr. Raymond Pearl of Johns Hopkins University reported that smokers do not live as long as non-smokers.

• By 1944, the American Cancer Society began to warn about possible ill effects of smoking, although it admitted that "no definite evidence exists" linking smoking and lung cancer.

The Tobacco Industry Responded Swiftly

• By 1954 the major U.S. tobacco companies had formed the tobacco industry research council to counter the growing health concerns.

• Mass-marketing began for filtered and low-tar cigarettes that promised a "healthier" smoke (now we know smokers compensate by smoking more and inhaling longer).

The Next Big Blow to Tobacco Industry

• 1964, Surgeon General's Advisory Committee on Smoking and Health put out a 387-page report stating that cigarette smoking is causally related to lung cancer.

• In 1965, Congress passed the Federal Cigarette Labeling and Advertising Act requiring the Surgeon General's warnings on all cigarette packages.

SURGEON GENERAL’S WARNING: Smoking Causes Lung Cancer, Heart

Disease, Emphysema, And May Complicate Pregnancy.

President Clinton announces Food and Drug Administration’s plan to

regulate tobacco, especially sales and advertising aimed

at minors

Smoking is banned on all interstate

buses and all domestic airline flights lasting 6

hours or less

Tobacco Industry on the Run

All broadcast advertising was

banned

19901971 1994

1995

Mississippi files the first of 22 state lawsuits seeking to

recoup millions of dollars from tobacco companies for

smokers’ Medicaid bills

Addiction to Smoking: A Global Problem

One-third of the global adult

population smokes.

Of those who smoke during adolescence and throughout

life, one-half die from smoke-related diseases.

•Smoking causes one-third of deaths in men aged 35-69.

•It is one of few causes of mortality that is increasing.

Smoking is Addictive

• 80% of attempts to quit smoking fail within a year.

• In the U.S., 70% of smokers say they would like to quit.

• 5% are successful each year.

Smoking Kills

Normal Lung Smoker’s Lung

The complex mixture called tobacco ‘tar’, and carbon monoxide, are mainly responsible for most of the diseases that are associated with the long-term use of tobacco.

Nicotine Addictive Component of Tobacco

• Nicotine produces effects that are commonly seen with other addictive drugs such as amphetamines and cocaine.

• Craving and self-administration• Increase in movements• Reinforces place reference (learned

associations – bars, restaurants, etc.)

Structure of Nicotine

Click here to learn more about how molecules interact with protein “receptors” on cell membranes.

The Idea of Molecular Receptors

• Drugs bind to cell membranes• Regions on membrane where this

binding occurs are called molecular receptors or binding sites

• Binding sites are proteins that are specific matches to the drug molecule (fit together like a key in a lock)

• Effect of the drug is achieved by this binding (like the key and lock, think of it as opening a function in the cell)

Long-Term Use Leads to Cigarette Cravings

• Long-term use increases the number of molecular receptors in brains of humans.

• Increased number of receptors increases the “demand” for nicotine

• When receptors are unoccupied by nicotine, they “complain” – “Where is our nicotine?”

Why Do Smokers Crave Nicotine?

• Nicotine acts in nervous system circuits that release a “reward” chemical – dopamine

• Brain learns to “like” the release of dopamine

• When nicotine is withdrawn, the brain’s reward system signals the craving to restore nicotine levels

Craving for Nicotine

• Craving is high when nicotine is at low concentrations

• Craving is satisfied when nicotine levels are restored to levels to which nerve cells have become accustomed.

• Nerve cells learn that nicotine is normal, lack of nicotine is abnormal

Craving Patterns

• After a night of abstinence, dopamine concentration in brain is at its lowest level.

• First cigarette strongly activates dopamine release. Greatest pleasure.

• Tolerance occurs quickly, because receptors adapt quickly.

• Throughout a day, episodes of cigarette smoking are separated by short periods of abstinence; nicotine levels drop and receptors “cry out for their nicotine fix.”

Addiction Process is Still a Mystery

• If an individual quits smoking for a few weeks, the number of nicotine receptors returns toward normal (like that of non smokers).

BUT …• Craving can still exist even years after quitting.

• Long-term changes have occurred in neural circuits.• Smokers remember the behaviors that were linked to

sensory cues and reinforced.

Think Before You Act

Smoking is the leading cause of premature death!