Nicotine Flashcards
What are the effects of nicotine
Reinforcing/Rewarding
Behavioral
Cognitive
Autonomic and physiological effects
What kind of drug is nicotine
Stimulant; relaxant
What is nicotine absorption dependent on?
pH dependent
How is nicotine absorbed in acidic conditions?
ionized –> poorly absorbed across membranes
How is nicotine absorbed in alkaline conditions?
Non-ionized –> well absorbed
How is nicotine absorbed in physiological pH
Nicotine is readily absorbed in pH around 7.3-7.5
How is nicotine metabolized
10-20% is excreted
70-80% is turned into cotinine
10% into other metabolites
what is the half life of nicotine
2 hours
what is the half life of cotinine
19 hours
how is nicotine excreted
through the kidneys (urine)
Breast milk
How is nicotine excretion affected by pH
Lower pH (acidic conditions) increases the rate of kidney excretion
How is nicotine able to act on the autonomic nervous system
Nicotine binds to nicotinic cholinergic receptors
What is required of the subunits of cholinergic receptors
at least two subunits have to be alpha
what are some important brain structures that nicotine acts on
striatum
amygdala
hypothalamus
substantia nigra; VTA
How do different subunit combinations of nAChR affect nicotine
they have differing rates of desensitization and different properties
How does nicotine affect the pain response
analgesic effect (increased latency of tail withdrawal)
What is the effect of nicotine dependent on
state of the person
What is an indirect result of nicotine consumption
increase in norepinephrine levels
What is the dual reinforcement model of nicotine
Nicotine is a primary reinforcer but it works but ENHANCING the reinforcing properties of other reinforcing stimuli
what happens to the reinforcement enhancing effect of nicotine when drugs that block nicotine receptors are added
the reinforcing effect was blocked showing that nicotine is directly responsible for the phenomenon
what is the relationship between the reinforcing stimuli and nicotine
the more reinforcing the stimulus is the greater the enhancement is by nicotine
what is different about buproprion
Has the same reinforcement enhancing effect but is not blocked by drugs that block actions of nicotine
what is different about varenicline
has reinforcement enhancing effects but also blocks the maximal reinforcing affects of nicotine
what is short term tolerance of nicotine
nicotine slowly dissociated from the receptor leading to desensitization (sometimes overnight)
what is characteristic of chronic smokers
increased expression of nACh receptors in the brain (longterm desensitization = upregulation)
what are some withdrawal symptoms of nicotine
headache, stomach pain, craving, depression, anger/irritability, anxiety, restlessness, poor concentration, insomnia, decreased HeartRate, increased appetite
what happens when smokers are given a nicotine antagonist
increased smoking to overcome antagonist
what happens when smokers are preloaded with nicotine
decreased smoking
what is nesbitt’s paradox
nicotine causes an arousal of brain activity and causes release of NE which activates sympathetic NS but smokers report that smoking “relaxes” them
what are some explanations for Nesbitts paradox
Acute nicotine deprivation leads to stress which leads to smoking to normalize their mood
