lecture 17 LOs Flashcards
in ‘drinker’ rats, what makes them this way
the dopamine system is much more responsive to alcohol than their counterpart non drinkers
endogenous opioids contribute to reinforcing effects of alcohol, how
- acute alcohol increases endorphin and enkephalin production or release
- alcohol-induced opioid release may contribute to its ability to increase DA release
- chronic alcohol reduces opioid production which may contribute to he dysphoria that accompanies chronic alcohol use and withdrawal
what do opioid receptor antagonists do to alcohol self administration
it reduces it
what happens to mu opioid receptor knockout mice
they fail to self administer ethanol
what is the mechanism of action for nicotine
acts as a direct agonist to active nicotinic cholinergic receptors
(excitatory effects on neural activity)
what does nicotine do to non smokers
aversive effects, elicits heightened tension/arousal, lightheadedness, dizziness, nausea
what does nicotine do to smokers
mild arousal (stimulant effect), calm or relaxed state (relief from withdrawal symptoms), appetite suppression
what cog effects can nicotine have on attention
enhancing effects
what NT plays a role in nicotine reinforcement
mesolimbic DA
where do nicotine receptors reside
DA neurons cell bodies (to stimulate firing and increase NAc DA release)
where does nicotine heteroreceptors reside
also on DA terminals in NAc (to increase transmitter release)
what lesions attenuate nicotine self administration
DA terminals in NAc
regarding nicotine, what happens when DA receptors are blocked
disrupts conditioned place preference to nicotine (measure of drug reward) and reinstatement of nicotine seeking, suggesting DA contributes to relapse
what is a genetic way to prevent nicotine self administration
genetic knockout of certain nicotine receptor subtypes
what are two examples of conditioned reinforcers for nicotine
sensory and temporal stimuli associated with the act of smoking become conditioned to reinforcing effects
what is acute nicotine tolerance and what is it mediated by
smokers experience reduced effects of nicotine over the course of a day
mediated by desensitization of nicotinic receptors
what is chronic tolerance
tolerance to aversive effects needs to occur for the smoker to experience the reinforcing effects of smoking
repeated nicotine also elicits compensatory up regulation of nicotinic receptors (triggered by acute desensitization), which can sensitize the system to nicotinic stimulation
psychoactive and physiological effects of withdrawal
psychoactive: irritability, drowsiness/fatigue, difficulty concentrating, anxiety, depressed mood, increased hunger and craving sweets
physiological: headache, nausea, constipation, falling heart rate
how do nicotine levels change throughout the day for smokers
early in the day there is increased plasma nicotine which elevates mood (above baseline), but later nicotine may merely maintain neutral mood (holding off the withdrawal symptoms)
what are the sex differences for smoking
fewer women than men smoke
women tend to smoke fewer cigarettes a day, inhale less deeply, are more influenced by the non nicotine aspects of smoking, and find it tougher to stop smoking
how does stress tie in to smoking
smokers say that smoking relieves stress and enhances ability to concentrate (nicotine resource model)
what is the nicotine deprivation reversal model
positive effects of smoking represent alleviation of irritability, stress, and poor concentration experienced by smokers between cigarettes (ex during withdrawal)
what is the medication buporpion used for
smoking cessation
acts as DA uptake inhibitor and weak nicotinic agonist
what does the medication varenicline do
reduces nicotine cravings
partial agonist at high affinity nicotinic receptors expressed in the VTA and other brain areas
how long does it take for caffeine to be absorbed by the GI tract, and what is its half life
30-60 mins for absorption
half life of ~ 4 hours
what do humans experience at high levels of caffeine
feelings of tension and anxiety
in some cases at extremely high doses it can induce psychosis
what are the physiological effects of acute caffeine intake
increased blood pressure and respiration
stimulation of catecholamine release from adrenal medulla
enhanced water excretion via suppression of antidiuretic hormone release
what does caffeine withdrawal look like
symptoms include headache, fatigue, impaired concentration/psychomotor performance, mild anxiety or depression
despite its ability to produce physical dependence, caffeine use typically does not meet criteria necessary to be considered addictive
in general caffeine is tought to be quire safe when consumed at appropriate doses and coffee/tea may have some beneficial health effects
