Lecture 16- Nicotine Flashcards
Exam 2
What does nicotine do to receptors?
- Nicotine is an agonist of the nicotinic acetylcholine receptor (nAChR)… cholinergic agonist
- nAChRs can depolarize neurons
- nAchRs are found throughout the nervous system (CNS and PNS)
In the dopamine reward pathway, nAChRs on dopamine neurons. What would this result in?
- Increased DA in nucleus accumbens
Tobacco has blank inhibitors, which further increase blank?
Monoamine oxidase (MAO) inhibitors, which further increase dopamine availability/
Where does nicotine have a higher affinity for and why?
- Nicotine has a higher affinity for the brain vs systemic/peripheral nACh repectors
- This is due to binding preference based on subunit composition of receptors (can bind more in homomeric)
What causes complex and unpredictable changes that occur after administration of nicotrine?
- actions on a variety of neuro-effector and chemosensitive sires
- stimulate receptors
Acute pharmacological effects of nicotine
- General CNS stimulant: increases behavioral activity, may produce tremors, stimulates vomiting center in brain stem (tolerance to this develops quickly), stimulates release of antidiuretic hormones from the hypothalamus, increasing fluid retention, reduces muscle tone by reducing activiy of afferent nerves from muscles, enhances alertness, learning, and memory
- Also: increases HR, BP, and heart contraction. Initiates dilation of arteries to meet heart’s increased oxygen demand caused by nicotine
Nicotine Poisoning/ Toxicity
- Fatal dose in adults around 60 mg (30 mg reported)
- Symptoms onset is rapid and includes nausea, salivation, abdominal pain, vomiting, diarrhea, cold sweat, headache, dizziness, distrubed hearing and viision, mental confusion, and marked weakness.
- Falling BP (rapid, irregular, weak pulse)
- Labored breathing
How much nicotine in tobacco?
- Smoking tobacco usually contains 0.5-2mg
- Total of 10-40 mg/pack of cigarettes
Nicotine tolerance
- tolerance is manifested by a more intense effect of the first time used during the day
- absence of nausea and dizziness with repeated intake
Withdrawal syndrome nicotine
- craving
- dysphoric/depressed mood
- insomnia
- irritability, frustration, anger
- anxiety
- difficulty concentrating
- restlessness, impatient
- decreased HR
- increased appetite/weight gain
Nicotine Use Disorder
- molecular involvement
- environmental stimuli
one of the hardest addictions to break
Molecule involvement (receptor dysregulation) with nicotine use disorder
- NAc/VTA may play predominant role in DA release
- Glutamatergic and cholinergic synaptic transmission
- GABAergic effects
- etc
Titration Theory of nicotine dependence
- Dependent smokers adjust their nicotine intake in order to maintain serum nicotine levels above a threshold level.
- If nicotine levels fall below the individual’s threshold, withdrawal symptoms appear
- Eperienced smokers arrive at a consistent style of smoking that provides their bodies w a relatively constant level of nicotine
Why is smoking so reinforcing?
- With around 10 puffs per cigarette, the one pack per day user reinforces the habit 200 times daily
- during dependence negative reinforcement kicks in, smoking to eliminate unpleasant state during acute withdrawal
What strengthens psychological dependence to nicotine?
-Social and environmental associations
-“rituals”
