psych 127b lecture 11 Flashcards
What is the GABA channel
an inhibitory ligand gated GABA chlorine channel
what allosteric ligands bind to the GABA channels
barbituates, benzodiazepines, alcohol, and neurosteroids
what are barbituates
-GABA-A/possibly glutamate agonist
-nonspecific inhibitory effect
-results in physical and psychological dependence (high abuse potential)
benzodiazepines
-allosteric effect less strong than barbituates
-GABA agonist
-anxiolytic (muscle relaxant)
-roofies are benzodiazepines
why is rohypnol (roofie) so powerful with alcohol
rohypnol and alcohol both act as GABA agonists (both amplify eachother)
alcohol
-also a GABA agonist, rapidly absorbed from GI tract, very permeable to the BBB, max. absorption at 30-90min
-metabolized in stomach and liver
-also an NMDA (glutamate) antagonist
ADH gene
genes which code for proteins in the liver and stomach which breaks down alcohol (women have less)
ALDH gene
-codes for the acetaldehyde enzyme (metabolite of alcohol)
- certain ALDH2 alleles mean this enzyme is inactive
-this is protective against alcoholism bc it causes unpleasant alcohol side effects
how does alcohol affect receptors long term
GABA receptors decrease sensitivity and NMDA receptors become more active (increased alcohol threshold and increased sensitivity to excitation)
where are CB1 cannibinoid receptors found
-on the prefrontal cortex region responsible for executive functioning
-works on the endocannibinoid system responsible for brain development (including during adolescence)
what are symptoms of marijuana withdrawal
irritability, anger, depression, lack of appetite
what are examples of opiates
morphine, vicodin, oxycodone, fentanyl, opium, heroin
what are the effects of opiates
analgesia, euphoria, drowsiness, slowed breathing, used for pain management post-surgery
dsm criteria for substance abuse disorders
impaired control, social impairment, risky use, and pharmacological impairment
sampling
-likeliness of a person to try a particular drug
-depends on availability, co-morbidity with other psychiatric disorders, experience with other substances, risk-taking tendencies
two main influencers of sampling
-genetic variation in dopamine receptors
-social variation
liking
-reinforced stimulus effects support the instrumental act to consume the drug again
-mediated by dopamine
-
positive reinforcement
when a drug has a positive effect which makes you want to do it again
negative reinforcement
when a drug alleviates negative things which makes you want to do it again
reward-deficiency syndrome
-hyposensitivity to reward
-underactive dopamine reward system
what are the three causes of reward-deficiency syndrome
-drug use
-cessation of drug use
-genetics
-any of these three can result in drug seeking
what causes positive reinforcement in amphetamine/methamphetamine
amphetamine/methamphetamine: stimulates dopamine terminal vesicles to release more dopamine
what causes positive reinforcement in cocaine
inhibits reuptake of dopamine
nicotine/weed/morphine
stimulates dopaminergic neurons more frequently
nicotine/weed/morphine
stimulates dopaminergic neurons more frequently
wanting
stimuli associated w drug intake provokes the desire for drugs and facilitates the act of drug taking
what causes the transition from liking to wanting
escalation of intake over time
-results in habitual use related to certain stimuli
-neuronal changes resulting in decreased tolerance
-behavioral changes also resulting in increased tolerance
needing
-physical dependence which results in a somatic state supporting avoidance behaviors
metabolic tolerance
-develops when continuous exposure results in the production of more liver enzymes to break down the drug
pharmacodynamic tolerance
occurs when receptors in the brain adapt to the presence of the drug via downregulation
physiological dependence
the development of tolerance to a substance or the presence of withdrawel when they stop taking that substance abruptly
psychological dependence
forceful, subjective urges to use substances often as a means of relieving negative mood states such as craving, irritability, insomnia, depression, or anorexia
how can genes affect addiction
-by altering the mechanisms of the drug, inhibiting the drug, or affecting the likeliness of an individual to take risks
what is agonist substitution
when you give a person with a dependence on a certain drug a similar drug with less harmful effects
what is agonist substitution
when you give a person with a dependence on a certain drug a similar drug with less harmful effects (ex. methadone)
antagonists
blocks the effects of a drug (ex. naltrexone-opiate antagonist)
aversive treatment
-“counter conditioning”
-makes the use of drugs very unpleasant
-high relapse potential
-ex. antabuse for alcoholism
subjunctive medication
-treats the symptoms of withdrawal ex. benzos for anxiety or wellbutrin for nicotine cravings
what are psychosocial treatments of addiction
-inpatient facilities, alcoholics/narcotics anonymous, controlled usage/moderation management, relapse prevention, prevention
