Chapter 15: Drugs and Behaviour Flashcards
oral administration
- most convenient
- takes longer to act
- requires highest dose
- digestive system acts as a barrier
absorption into skin tissue
- continual, slow release into the bloodstream
- bypasses the digestive system
- faster acting than oral method
sublingual absorption
- pill is dissolved under the tongue
- enters blood stream through membranes in the mouth
- lower dose compared to oral
inhalation
- reaches brain via blood flow from lungs
- acts within seconds
injection directly into the bloodstream
- goes to the brain within seconds
- less of a dose is required
what are the two main pathways in the dopaminergic system?
- mesolimbic pathway (nucleus accumbens)
- nigrostriatal pathway (substantia nigra)
nucleus accumbens
anticipates when a reward is coming and responds when you engage in rewarding behaviour
striatum
involved in movement and processes stereotypical behaviours that lead to a reward
limbic system
made up of the amygdala (emotional experience) and the hippocampus (long-term memories of rewarding experiences)
prefrontal cortex
involved in reasoning and decision making
functional tolerance
occurs at the level of the synapse, higher and higher doses are needed to feel the same effect
metabolic tolerance
the drug is broken down more easily and the effect doesn’t last as long
what does the effective duration of many drugs depend on?
the liver’s ability to metabolize it
when is someone most at risk of suffering an overdose?
when they take a break and then start using a high dose again without the same tolerance
physiological dependence
produces withdrawal symptoms
psychological dependence
produces cravings
what does drug dependence rely on?
- positive reinforcement (want to feel good; how dependence starts)
- negative reinforcement (want to avoid withdrawal symptoms; how dependence in maintained)
incentive sensitization
people become more sensitive to all things associated with the drug
epigenetic mechanisms of addiction
- repeated drug use alters gene transcription factors in the reward pathway, which leads to long-term changes in the brain
benzodiazepines
- minor tranquilizers, anti-anxiety agents, and mild sedatives
- make you less alert
barbiturates and alcohol
- produces sedation and can induce sleep
cross tolerance
develop a tolerance to a drug that isn’t being taken because they operate by the same method at the synapse
GABAa receptor binding sites
- alcohol and barbiturates
- benzodiazepines
what does heavy, long-term alcohol use lead to?
alters GABA receptors
what are the withdrawal symptoms associated with alcohol?
anxiety, convulsions, and occasionally seizures
which neurotransmitters does marijuana release?
dopamine and GABA
GHB (date rape)
- form of salt
- rapid absorption
- high doses cause dizziness, sleep, vomiting
- used to treat alcohol withdrawal
ketamine (surgical anesthetic)
out of body experience
what are the symptoms of schizophrenia?
hallucinations, delusions, and psychosis
what was the first antipsychotic drug?
chlorpromazine
what is the intentional use of chlorpromazine?
general anesthetic for soldiers but ended up being used pre-surgery to calm down the patients
first generation antipsychotics
dopamine antagonists (can bring people out of a psychotic state)
what are the side effects associated with first generation antipsychotics?
- tardive dyskinesia (unwanted movements)
- anhedonia (inability to feel joy)
what do second generation antipsychotics act on?
dopamine and serotonin receptors
first generation antidepressants
- monoamine oxidase (MAO) inhibitors
- tricyclic antidepressants
what are the side effects associated with first generation antidepressants?
elevated blood pressure
second generation antidepressants
- SSRIs (inhibit serotonin reuptake)
- SNRIs (act on serotonin and norepinephrine)
- ketamine
morphine
synthesized from the active ingredient found in opium in the early 1800s
heroin
synthetic derivative opioid
how does heroin compare to morphine?
shorter half life and twice the potency
fentanyl potency
80 times that of morphine `
what are the withdrawal symptoms associated with opioid analgesics?
- respiratory suppression (high doses)
- allodynia (skins becomes sensitive/person may feel pain)
- myoclonic movements (jerking, reflexive movements)
naloxone
opioid antagonist that helps with overdose symptoms
opioid mechanisms of action
bind to opioid G-protein coupled receptors (endorphins) located throughout the body
what are the mechanisms of opioid tolerance?
- desensitization (G-protein can decouple from the receptor)
- endocytosis (receptor sinks down into the cell and is less exposed in the synapse)
- downregulation (receptor disappears from the synapse)
general stimulants
drugs that cause a general increase in the metabolic activity of cells
what are some examples of stimulants?
caffeine, nicotine, cocaine, methamphetamine, MDMA
what can stimulants be used to treat?
ADHD
nicotine
- acts on acetylcholine receptors
- can increase focus and attention
cocaine
- can be snorted, smoked, or injected
- rapid rate of tolerance
- alcohol enhances the effects
- more intense and addictive in females (related to estrogen receptors)
methamphetamine
- smoked or injected
- low doses elevate mood and increase energy and alertness
- higher doses can produce hallucinations and psychosis
- chronic users show evidence of cell loss (reduced hippocampal volume)
MDMA
- taken in pill form
- slow to act but lasts for hours
- sense of euphoria and heightened awareness
hallucinogens
alter sensory perception and produce vivid hallucinations
who discovered LSD?
Albert Hofmann (1943)
mescaline
dried tops of the peyote cactus (hallucinogen)
