psychoactive plants stimulants - ii: nicotine. nicotine major alkaloid in the genus nicotiana...
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Psychoactive PlantsStimulants - II: Nicotine
Nicotine Major alkaloid in the genus Nicotiana
Nicotiana, a large genus mainly from New World (~ 65 species) in the Solanaceae
Cultivated species: N. tabacum & N. rustica
Nicotiana tabacum
Tobacco history New World usage 1492 – Columbus Introduction to Europe British colonies
Nicotine Major alkaloid First isolated early in 19th century Synthesized in roots of tobacco plant and
translocated to the leaves One of the most toxic plant poisons In pure form, nicotine is deadly, causing death
by respiratory paralysis Nicotine is the most addictive drug in
widespread use
Nicotine
Nicotine insecticides Effective against most all types of insect
pests, but is used particularly for aphids and caterpillars - soft bodied insects
Mimics acetylcholine at the neuromuscular (nerve/muscle) junction and results in twitching, convulsions, and death
Same action is observed in all insects
Nicotine effects and mode of action Acts as a CNS stimulant and also affects peripheral
nervous system Stimulation of adrenal glands and discharge of
epinephrine (adrenaline) Nicotine also suppresses insulin output from the
pancreas, which means that smokers are always slightly hyperglycemic
In addition, nicotine indirectly causes a release of dopamine in the reward region of brain that controls pleasure and motivation
Mode of action on brain Nicotine exerts its effects in the brain by acting on a
specific type of receptor for acetylcholine, known as the nicotinic receptor
These receptors on dopamine neurons within the ventral tegmental area
Activates acetylcholine receptors (locks the channel open) - this increases the activity of these dopamine neurons, leading to an increase in dopamine release in synapse, which is thought to mediate reward
Nicotinic Receptor Researchers believe the beta 2 subunit of the
nicotinic receptor is a critical component in nicotine addiction
Mice that lack this molecule fail to self-administer nicotine, implying that without the beta 2 molecule, the mice do not experience the positive reinforcing properties of nicotine
This suggests a potential site for targeting the development of anti-nicotine addiction medications
Other Psychoactive Compounds? Research is also beginning to show that nicotine may
not be the only psychoactive ingredient in tobacco Cigarette smoking results in a marked decrease in
the levels of monoamineoxidase (MAO) in the brain MAO an important enzyme that is responsible for
breaking down dopamine.
The decrease in two forms of MAO, A and B, results in higher dopamine levels
Also a depressant?
Health Risks King James I of England in 1604 1948 JAMA
“More can be said in behalf of smoking as a form of escape from tension than against it....”
In 1964 U.S. Surgeon General’s report stated that cigarette smoking linked to lung cancer, heart disease, emphysema, and other conditions
Cigarette smoking the number one cause of preventable death
Cigarette smoking leading cause of death in US
Cigarette Smoking Most prevalent form of nicotine addiction Most cigarettes today contain 10 mg or more of
nicotine Through inhaling smoke, the average smoker takes
in 1 to 2 mg nicotine per cigarette Smoking results in rapid distribution of nicotine
throughout the body, reaching the brain in 10 sec Delivery to the brain Other forms of tobacco
Over 438,000 Annual Deaths in US Due to Cigarette Smoking
Risk of Cancer 85% to 90% of all lung cancer is due to cigarette
smoking About 1/3 of all cancer cases are due to cigarette
smoking Smoking associated with cancers of mouth, pharynx,
larynx, esophagus, stomach, pancreas, uterine cervix, kidney, ureter, bladder, colon, and leukemia
Chewing tobacco strongly linked to oral cancer - 50X increase in risk of oral cancer
Tobacco Smoke Over 4,700 chemical compounds found in tobacco
smoke Several (43) cancer causing substances Several alkaloids in addition to nicotine although
nicotine not implicated in cancer there is some evidence that it is converted to a carcinogenic cmpd in the body
Tars may be the leading carcinogens in cigarette smoke However, low tar cigarettes do not decrease incidence of
smoking related diseases
Cardiovascular Disease Smoking increase risk of cardiovascular disease
including stroke, sudden death, heart attack, peripherall vascular disease and aortic aneurism
Cigarettes caused almost 180,000 deaths from cardiovascular disease (1990)
Components of smoke also damage lining of blood vessels which can lead to atherosclerosis
Pulmonary Disease Cigarette smoking the leading cause of pulmonary
disease In 1999, there were over 82,000 deaths from
pulmonary disease in US – mainly from pneumonia, emphysema, bronchitis
In a recent study, maternal cigarette smoking the single most important risk factor in children developing asthma – way ahead of all other risk factors
Passive Smoking Smokers not the only ones affected by
cigarette smoke Much research has focused on the risks of
secondary smoking 53,000 annual deaths in US A non-smoker living with a smoker has a 30%
higher risk of death from coronary heart disease and a 30% or higher risk of lung cancer depending on exposure
Smokers 22.8% of the US population smokes cigarettes Decrease from 25% in 1998 Decrease greater among men than women Women now account for 39% of the smoking related
deaths – lung cancer has surpassed breast cancer as leading cause of cancer deaths among women
Smoking by teens continues to be a major problem but has actually decreased in the past few years
Tobacco Use in the US, 1900-2002
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
1900
1905
1910
1915
1920
1925
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Year
Per
Cap
ita
Cig
aret
te C
onsu
mpt
ion
0
10
20
30
40
50
60
70
80
90
100
Age
-Adj
uste
d Lu
ng C
ance
r D
eath
R
ates
*
*Age-adjusted to 2000 US standard population. Source: Death rates: US Mortality Public Use Tapes, 1960-2002, US Mortality Volumes, 1930-1959, National Center for Health Statistics, Centers for Disease Control and Prevention, 2005. Cigarette consumption: US Department of Agriculture, 1900-2002.
Per capita cigarette consumption
Male lung cancer death rate
Female lung cancer death rate
Trends in Cigarette Smoking Prevalence* (%), by Gender, Adults 18 and Older, US, 1965-2004
*Redesign of survey in 1997 may affect trends.Source: National Health Interview Survey, 1965-2004, National Center for Health Statistics, Centers for Disease Control and Prevention, 2005.
0
10
20
30
40
50
60
1965
1974
1979
1983
1985
1990
1992
1994
1995
1997
1998
1999
2000
2001
2002
2003
2004
Year
Pre
vale
nce
(%)
Men
Women
Trends in per capita cigarette consumption for selected states and the average consumption across all states, 1980-2003
0
20
40
60
80
100
120
140
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Year
Per
Cap
ita S
ales
(#
of P
acks
) United States
Massachusetts
California
Data from: Orzechowski W, Walker RC. The tax burden on tobacco: historical compilation 2003: Volume 36. Arlington (VA): Orzechowski and Walker; 2003.
Trends in Smoking Among Teens
Current* Cigarette Smoking Prevalence (%), by Gender and Race/Ethnicity, High School Students, US, 1991-2003
*Smoked cigarettes on one or more of the 30 days preceding the survey.Source: Youth Risk Behavior Surveillance System, 1991, 1995, 1997, 1999, 2001, 2003, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, 2004.
28
35
31
13
16
27
23
11
1918
19
3230
11
14
23
40
37
12
28
33
4040
17
32
36
28
34
39 38
22
32
18
33
2726
0
10
20
30
40
50
White, non-Hispanic Female
White, non-Hispanic Male
AfricanAmerican, non-
Hispanic Female
AfricanAmerican, non-Hispanic Male
Hispanic Female Hispanic Male
Pre
vale
nce
(%
)
1991 1995 1997 1999 2001 2003
Tobacco Industry Legal battles By end of 1998 all 50 states and DC had reached
settlements with 5 largest tobacco companies Master Tobacco Settlement which will cost the
tobacco companies over $200 billion Federal legislation
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