Nicotine and CaffeineChapter 12

Leaves of the Nicotiana tabacum plant

Nicotine

History

Nicotine

Routes of Administration

Inhalation

Chewing

Snorting

Transdermal

Metabolism of Nicotine

• liver converts nicotine into metabolites

• cotinine

• half life: 2 hrs

• acute tolerance

Nicotine

Site of action for nicotine• Nicotinic cholinergic receptors (nAChR)

– Basic functions of different receptors:• Open Na+ channels increase firing potential

• Allows Ca2+ into cell 2nd messengers

• Enhances NT release (presynaptic)

Nicotine

Site of action for nicotine• Nicotinic cholinergic receptors (nAChR)

– Locations of receptors• Neuromuscular junction at muscles

• PNS

• CNS– Postsynaptic

– Presynaptic membranes of other NT neurons

Nicotine

Changes in cognitive functionNicotine-induced reduction of reaction time in a rapid visual information processing task

Nicotine

Activation of mesolimbic dopamine system

Time

Nicotine

Activation of mesolimbic dopamine systemNicotine self-administration in rats first exposed to the drug during adolescence vs. adulthood

Nicotine

Changes in mood

• Smokers

• Non-smokers

Nicotine

Factors other than NicotineWhole-body PET scans illustrating reduced MAO-B activity

Nicotine

Tolerance- acute

- chronic

Withdrawal symptoms– Decrease heart rate and blood pressure

– Irritability

– Hunger

– Sleep disturbances

– GI complaints

– Headache

– Impairment of concentration

Nicotine

Effects of smoking on general health

Increased risk for:• Cancer• Cardiovascular disease• Emphysema• Chronic bronchitis• Decreased birth weight in infants for mothers who

smoked

Nicotine

Why do people smoke?

• Nicotine resource model

• Deprivation reversal model

• Positive reinforcement (DA reward system)

• Substances other than nicotine

• Genetic factors?

Nicotine

Treatment of nicotine dependence

Nicotine

http://scienceblogs.com/retrospectacle/upload/2007/04/caffeine.jpg http://www.caffeinemedia.com.au/images/Caffeine-Holding-Page_03.jpg

Caffeine

Absorption and Metabolism

Caffeine

Mechanism of action

• Adenosine antagonist

Caffeine

Withdrawal and ToleranceTime course of caffeine withdrawal in regular users (Part 1)

Caffeine

Withdrawal and ToleranceTime course of caffeine withdrawal in regular users (Part 2)

Caffeine

Withdrawal and ToleranceTime course of caffeine withdrawal in regular users (Part 4)

Caffeine