Nicotine Flashcards
What is the number one cause of preventable premature death in North America?
Smoking.
Read slides 1-15 for history and prevalence data.
:)
How many chemicals can be found in a cigarette?
> 7,000 in tobacco and tobacco smoke.
List some dangerous chemicals found in cigarettes.
- acetone
- acetic acid
- ammonia
- arsenic
- benzene
- butane
- cadmium
- CO
- formaldehyde
- hexamine
-lead - naphthalene
- methanol
- nicotine
- tar
- toluene
List the short-term effects of tobacco use.
- euphoria
- enhanced cognition (attention)
- decreased appetite
- stimulation of nausea and vomiting reflex
- increased heart rate, breathing rate and blood pressure
- CO blocks O2 from getting into the bloodstream
- bad breath
- stimulation of the reward system and other neurochemical systems
List the neurochemicals. involved in the short-term effects of tobacco use and their effects.
1) DA
→ pleasure, reward
2) Serotonin
→ mood modulation, appetite suppression
3) NE
→ arousal, appetite suppression
4) Acetylcholine
→ arousal, cognitive enhancement
5) Glutamate
→ learning, memory enhancement
6) Beta-endorphin
→ reduction of anxiety and tension
7) GABA
→ reduction of anxiety and tension
List the long-term effects of tobacco use.
- tobacco addiction
- bronchitis, emphysema, COPD
- heart and artery disease
- cancer
- diabetes
- osteoporosis
- vision changes/loss
- fertility problems
On average, people who smoke die _____ years earlier than non-smokers
13 to 14 years.
List the long-term effects of adolescent tobacco use.
1) altered trajectory of normal brain development
2) diminished cognitive function that persists into adulthood
3) greater mental health problems
How does adolescent tobacco use alter the trajectory of normal brain development?
1) dendritic remodeling
2) lower gray matter volume in the thalamus and amygdala
3) aberrant functional connectivity
4) changes in the reward system
5) changes in 5-HT synaptic function
How does adolescent tobacco use diminish cognitive function that persists into adulthood?
1) reduced attention
2) poorer memory
3) enhanced impulsivity and lower inhibitory control
T or F: Damages to cognitive function resulting from adolescent tobacco use are reversible.
False.
There is no recovery of the cognitive deficits resulting from adolescent tobacco use.
How does adolescent tobacco use cause greater mental health problems?
1) increased anxiety and depression-like behaviours in adults
2) more severe tobacco addiction later in life
T or F: Adults show comparable effects to those who used tobacco during adolescence.
False.
Tobacco exposure in adolescence has effects that last into adulthood; adults do not show comparable effects.
T or F: Most smokers begin smoking during adulthood, around age 30.
False.
83% of all smokers began smoking during adolescence, between the ages of 14-25.
List some risk factors for tobacco use disorder (TUD).
1) genetic predisposition
2) parental exposure
3) lower SES
4) peer pressure
5) poor academic performance
6) impulsivity
7) low self-esteem
8) mood disorders
9) mental illness
10) substance use
11) onset of tobacco smoking during childhood or adolescence
What is the greatest risk factor for TUD?
Onset of tobacco smoking during childhood or adolescence
T or F: Americans can get about 9mg of nicotine per cigarette.
False.
American cigarettes contain about 9 mg of nicotine, but because much of the nicotine is burned off, a smoker gets about 1 mg of nicotine in every cigarette.
T or F: Nicotine is a stimulant.
True.
Define: Nicotine.
Primary psychoactive component of tobacco which underlies the addictive properties of tobacco.
What is the most common mode of delivery for nicotine?
Cigarettes.
How is nicotine delivered to the brain via cigarettes?
1) When smoked, nicotine is distilled from the tobacco and is carried in smoke particles into the lungs.
2) It moves quickly to the brain (10-15s).
3) It binds to nicotinic acetylcholine receptors (nAChR)
4) The onset of CNS actions occur within seconds.
T or F: For nicotine to reach the brain, IV is faster than smoking.
False.
Define: Nicotinic Acetylchlorine Receptors (nAChR)
nAChR are ligand-gated ion channels that play a key role in modulating neuronal excitability.
Which ions do nAChR regulate?
nAChR regulate the flow of cations Na+, K+, Ca2+ across the cell membrane.
Describe the structure of nAChR.
5 distinct membrane-spanning units (alpha/beta) combine to form a functional receptor.
How many alpha nAChR subunit isoforms exist?
9 (alpha2-alpha10)
How many beta nAChR subunit isoforms exist?
3 (beta2-beta4)
T or F: There are a limited number of nAChR heteromeric subtypes.
False.
There are many nAChR subtypes, and each is composed of various combinations of alpha/beta units.
What are the most abundant nAChR subtypes in the brain?
1) alpha4-beta2
2) alpha7
T or F: Nicotine has high affinity for he alpha4-beta2 and alpha7 subtypes.
False.
Nicotine has the highest affinity for alpha4-beta2 and low affinity for alpha7.
List the regions of the brain in which nAChR can be found.
1) cortex
2) hippocampus
3) amygdala
4) NAcc
5) caudate, putamen
6) VTA
7) cerebellum
8) thalamus
9) insula
In the brain, in which part of the neuron are nAChR mostly expressed?
Pre-synapse
Which compounds act as nAChR agonists?
1) Acetylcholine
2) Nicotine
Describe nAChR activation and desensitization.
1) Activation of nAChR occurs when acetylcholine or nicotine binds.
2) Binding induces a conformational change that allows cations to flow through an intrinsic channel, causing depolarization of the neuron.
3) Following activation, nAChR enter into a desensitized state, where channels close and the receptor cannot be reactivated
Slide 29
The nAChR desensitization state limits the duration of _____
Acute effects
T or F: The receptor spends more time in the activation phase compared to the desensitized phase.
False.
The receptor spends more time in the desensitized phase compared to the activation phase.
T or F: Desensitized nAChR have low affinity for ligands.
False.
Desensitized nAChR still have high affinity for ACh and other ligands, but the receptor is inactive.
In which phase is GABA tone strongest?
Active > Inactive > Desensitized
In which phase is DA neuron tone strongest?
Desensitized > Active > Inactive
What are the consequences of nAChR desensitization linked to nicotine?
1) Decreased receptor responsiveness for a subsequent stimulus
2) Reduced satisfaction of nicotine
3) Acute tolerance of nicotine
T or F: with acute nicotine use, nAChR do not regain sensitivity once desensitized.
False.
nAChR regain sensitivity and can become reactivated.
However, with chronic nicotine use, nAChR spend more time in the desensitized state.
T or F: Chronic nicotine use leads to the downregulation of nAChR.
False.
Chronic nicotine use leads to the upregulation of nAChR.
It sesults from the frequent desensitization of nAChR.