Exam 2: Nicotine and Caffeine Flashcards by jnauman@tulane.edu Nauman

Nicotine Administration Route etc.

Plant Alkaloid
Base with pKa 8.5

Inhalation
Buccal
Nasal
Transdermal

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Biotransformation of Nicotine

Nicotine (2 hr. 1/2 life)

CytoP450

Cotinine (16 hr. 1/2) life

Oxidation

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Risk factors for nicotine addiction

Fast metabolism
Caucasians
females

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Is nicotine itself what cause health problems?

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What creates acetylcholine from acetyl CoA and Choline?

ChAT

Choline
Acetyltransferase

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What breaks down acetylcholine from acetyl CoA and Choline?

AChE

Acetylcholinesterase

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Cholinergic pathways

Hippocampus: LDT/PPT; lateral dorsal tegmentum/peripeduncular tegmentum

Axon terminals: VTA, ventral tegmental area

Goes back ground to VTA to terminate in cortex/hippocampus

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Cholinergic cellbodies in front part project to cortex and hippocampus, but they ___

die in alzheimers

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Nicotine acts like

acetylcholine

agonist

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Types of nicotine receptors

ionotrophic and metabotrophic

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Nicotinic ionotrophic receptors

2x acetylcholine or nicotine molecules binds

Na+ enters
binds betwen alpha4/beta2

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Is nicotine an agonist or antagonist? (Tricky)

Both. At first, agonist. But then, antagonist. When clear system, receptor back to desensitized state, then wants nicotine again. Causes dependency

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Cholinergic nicotinic receptors

Skeletal muscles, brain neurons, ANS, Adrenal medullary cells

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What acetylcholine receptor leads to tremor?

Nicotinic

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What predominates in nicotine activation?

Parasym.

has M and N receptors

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Nicotine effects on mood (acute)

arousal, alertness, attentive, relaxed

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Sympathetic effects of nicotine

respiration, hear rate and bp go up

suppressed appetite
decreased diuresis

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Parasympathetic effects of nicotine

increased GI activity

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Acute toxic effects of nicotine

dizziness, nausea, vomiting

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Other toxic effects of nicotine:

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Area postrema 
Twitches/tremors- high doses
Seizures- stimulant
Respiratory suppression: blocks contraction of respiratory muscles AND inhibits medullary respiratory centers.
Even death

Will nicotine stimulate or inhibit respiration?

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Small = stimulate
High = repress

Nicotine at Nm (muscles) at high dose

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twitch
tremor
paralysis

What is amount for nicotine poisoning?

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500 mg (60 mg?)
1 cigarette = 15mg

How does repiratory suppression work at high doses?

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1) blocks contraction of respiratory muscles

2) inhibiting medullary respiratory centers

Therapeutic Uses

current: smoking cessation, other diseases under study.

Chronic smoking: Physical withdrawal

Tolerance and withdrawal syndrome. Irritability, anxiety, distraction, restlessness, insomnia, hunger, weight gain

A4-beta2 | (nACh nicotinic receptors) + radio tracers, what happens?

Nicotine displaces radio labelled tracers. 3 puffs = 75% displacement. When smoking stops and receptors later exposed, hypersensitive and start to experience withdrawal symptoms.

Microdialysis

technique used to measure release of NT from certain brain areas in rodent, insert into rat brain, pump fluid, CSF flushes araea and draw back up, get the NT release in certain region.

Microdialysis of dopamine release

NA pump fluid out, draw it out, look at release in NA. high Dose = higher dopamine release in NA

Where is the dopamine released?

When tobacco is burned?

1) Carcinogens (benzene, formaldehyde, vinyl chloride) 2) Toxic metals 3) Poisons (ammonia, CO)

Smoking on cardiovascular system

1) Increases demand (heart rate/bp) 2) Reduces oxygen supply to heart (atherosclerosis, CO reduces affinity of hemoglobin for oxygen, impairs pulmonary function (chronic obstructive pulmonary disease)

Emphysema

damage to alveoli, not reversible

Chronic Bronchitis

inflammation of bronchial tubes

Only ___ that try to quit smoking actually quit.

1/5 (20%)

Pharmacotherapy for smoking addiction

Buproprion antidepressant blocks dopamine reuptake Varenicline partial nicotinic receptor agaonist Nicrotine replacement to occupy receptors

Caffeine is just

Xanthine with a whole lotta methyl (-CH3)

Caffeine (kinetics): 1) Administration 2) Acid/base? 3) 1/2 life?

Oral Base 4 hr Cross BBB metabolized to paraxanthine, (84%) theobromine, (12%) theophylline (4%)

Normal doses of caffeine block

adenosine receptors (A2a), mild dis inhibition. when blocked by methylxanthine

Very high doses of caffeine will do what 3 things?

1) inhibit phosphodiesterase 2) Block GABA-A receptors 3) Increase calcium release

Acute cognitive effects of methylxanthines

arousal, alterness, wakeful, energy concentration, reaction, dexterity

Acute physiological effects of methylxanthines

decrease blood flow to brain increased/decreased risk of migraines? increase respiration dilated airways increased gastric secretions diuresis

Toxic effects of caffeine (500-1000 mg)

Anxiety, irritability, insomnia, fever, flushed

Toxic effects of caffeine >1500 mg

paranoia, delusions, hallucinations, stereotypies

Therapeutic uses of methylxanthines (caffine)

Headache, asthma, sleep apnea, narcolepsy

Caffeine tolerance

increased adenosine receptors

Caffeine dependence

physical: headache, fatigue, craving Positive reinforcement: weak, increase dopamine in cortex

Why is caffeine associated with lower risks of certain disease?

anti oxidants which are anti inflammatory

Exam 2: Nicotine and Caffeine Flashcards

(48 cards)