Lecture 14- Stimulants Flashcards
Exam 2
Cocaine Neurotransmission and PD
Acutely: Blocks transporter reuptake of dopamine, norepinephrine, and serotonin
Amphetamine Neurotransmission
- Can block and reverse transporter (NT gets dumped back into the cleft) re-uptake of dopamine, norepinephrine, and serotonin
- Blocks enzymes (monoamine oxidase) that degrade monoamines (dopamine and norepinephrine) which prevents degradation and break-down
- Blocks transporter that fills vesicles with monoamines
What is monoamine oxidase?
- An enzyme that degrades monoamines (like dopamine and norepinephrine)
Positive effects associated with cocaine and amphetamine use
- sympathomimetic (mimcs activation of the sympathetic NS, where the idea of stimulant comes in)
- dose dependent increase in heart rate and blood pressure
- increased arousal
- improved performance on tasks of vigilance and alterness
- increased sense of self-confidence and well-being
- higher doses produce brief duration of euphoria followed by desire for more durg
- self reported to produced prolonged, intense orgasm… (could j be bc associated w compusive, promiscuous sexual activity)
- reinforcing and craving-inducing effects lead to binge use followed by a crash
Stimulants side effects
- appetite suppressant
- sleep prevention
- irritability
- involuntary motor activity
- arrythmias (irregular heartbeat)
- formication (feeling of bugs crawling on/under skin)
- snow lights (visual disturbances)
- stereotyped behavior
- paranoid delusions (stimulant psychosis)
- overdose/death
- seizures
- depression
- most of drug-related ER visits (in 90s, is now opiods)
- dose-dependent
What are paranoid delusions/stimulant psychosis and how can it be treated?
- Similar to paranoid schizophrenia
- Can be treated with drugs for schizophrenia (i.e. chlorpromazine- dopamine D2 antagonist)
Long term high dose effects of stimulant use
- paranoia
- psychotic behavior
- interpersonal conflicts
- co-morbidity w almost every psychiatric syndrome
- bizarre or violent behavior (can endure for long periods after stopping usage)
- problems with other drugs of misuse
- hallucinations
- etc
How do the high/low mood swings of stimulant use vary between high vs. moderate use?
- With heavy both peaks and crashes were of higher magnitude
- biggest thing we need to overcome w stimulants is using the substance to break cyclical depression that occurs after usage
Tolerance w Stimulants
- experienced users report tolerance to euphoric feelings
- Tachyphylaxis (rapid acute tolerance) is observed w reduced effects at the same dose given repeatedly in one session
Withdrawal Cocaine
- intermittent use contributes to withdrawal
- Dysphoria, depression, sleepiness, fatigue, bradycardia, profound craving
What is the major treatment problem with cocaine?
helping patients resist urge to start compusive cocaine use
Sensitization and stimulants
- Sensitization consistently found in studies of stimulants in animal models, contributed by intermitten use and measured by behavioral hyperactivity. Rats w cocaine history have a huge response when injected for the first time again after an abstinence period
- In humans it likely involves behavioral conditioning (anticipation). Cocaine users report strong response in seeking cocaine before administration of physiological arousal and increased drug craving
VTA-Nucleus Accumbens
- positive reinforcement reward pathway
- when a rewarding stimulus is experienced, this leads to activation of dopamine neurons in the VTA
- Consequenctly, more dopamine is released to the Nucleus Accumbens which is reflective of positive reinforcement
- This is what u experience when you receive a positive rewarding stimulus (may differ w addicts)
Brain stem to amygdala
negative reinforcement
-in a nondependent individual the positive reinforcement system is activated when a drug is takem but after the drug has circulated, the negative reinforcement system becomes engaged
What is reinforcement like when there is dependency (someone w a history)?
- The negative reinforcement network is more activated
- So, the person takes the drug to get rid of an unwanted affect, not just to feel a positive effect
