(5) neural communication II & drug properties (midterm 2) Flashcards
What is the role of serotonin?
- primarily from raphe nuclei (brain stem)
- precursor - tryptophan:
- process to cross bbb requires carbs
- serotonin depletion:
- increased aggression, impulsivity
- decreased cognitive flexibility
- hallucinogens act on its receptors
What is the role of acetylcholine?
- neuromuscular junction
- also basal forebrain: wakefulness, attention, etc.
- nicotine: acetylcholine agonist
What is the role of endocannabinoids?
- retrograde transmission: travels from dendrite to axon
- mechanism for forgetting: weaken connection b/w 2 cells at synapse
What is the role of adenosine?
- ATP is cellular energy
- adenosine is ATP byproduct
- caffeine/theophylline, adenosine inhibitor
- one of the mechanisms for sleepiness
What is the role of endogenous opiods?
- aka Endorphins
- giant peptide NTs
- NT systems that exogenous opioids (e.g. heroin) mimic
- fentanyl & naloxone: opiod receptor antagonists
- all G-protein-coupled receptors:
- found in spinal cord, periacqueductal grey, nucleus accumbens
- pain relief: blocks pain receptors
- causes euphoria
What is propranolol?
- norepinephrine receptor antagonist
- beta-blocker
- affects brain & heart
- potential PTSD treatment via reconsolidation:
- reconsolidation: take memory from long term to working
- decrease emotional response to traumatic event
What are SSRIs?
- for depression
- all but 1 are metabotropic receptors
- block serotonin from being removed from synapse, agonist-like effect
- quick effects, slow improvements
efficacy:
- mild-moderate depression: no better than placebo
- major depression: effect size small
- regression to the mean: unsure if effect is due to SSRI or natural improvement
What is the 1st stage of pharmacokinetics?
- absorption
- drug administration
- absorbed into bloodstream
- routes of administration
What are routes of administration?
- intravenous: injecting into bloodstream
- intramuscular: injecting into muscles
- subcutaneous: injecting under skin
- per os (by mouth)
- inhalation
- insufflation: “snorting”
What are features for each route of administration?
intravenous:
- highest concentration in blood
- broken down most quickly
intermuscular:
- fast, painful, high concentration in blood
- effects slightly longer than intravenous
subcutaneous: not as potent but longer effects
per os: v. long effects, takes long time, lower potency
inhalation: thru lungs
insufflation: absorbed by mucus membranes
What is the 2nd stage of pharmacokinetics?
- distribution
- passage from bloodstream into organs
- must penetrate membranes
What is the 3rd stage of pharmacokinetics?
- biotransformation
- drug broken down into metabolites by enzymes
What is the 4th stage of pharmacokinetics?
- elimination
- drugs/metabolites or both eliminated from body
What might an instrumental/recreational user of a drug want in terms of routes of administration?
instrumental: per os
- looking for long-lasting effects
recreational: intravenous
- looking for strongest effect
How does a drug’s acidity relate to its absorption?
drug pKa & environmental pH:
- acidic/basic drug more likely to be absorbed in acidic/basic environment
What is bioavailability?
ability for drug to reach its target
What factors diminish bioavailability?
- blood-brain barrier
- nonspecific binding
- first-pass metabolism
- active metabolites
- prodrugs
What is nonspecific binding?
drugs binds to things other than site of action
What are first-pass metabolites?
drug broken down before it reaches site of action
What are active metabolites?
metabolites of drug that still have psychoactive effect
What are prodrugs?
chemicals that become drugs when metabolised
What kind of drugs is able to cross the blood-brain barrier better?
small, uncharged, lipid soluble drugs
What effect would active metabolites have on the drug-taking experience?
can increase drug experience
How does binding affinity relate to a drug’s effects?
Binding affinity: how strongly drug binds to receptor
- dissociation constant: Ka
- drugs w/ high binding affinity → low Ka
- drugs w/ weak binding affinity → high Ka
How does receptor efficacy relate to a drug’s effects?
Receptor efficacy: how effective drug is at activating receptor
- although drug may bind strongly to receptor, doesn’t mean it is effective at activating it
How is tolerance an effect of long-term drug use?
tolerance: need higher dose of drug to get same effect
- regular, everyday use
How is sensitisation an effect of long-term drug use?
sensitisation: adaptations appear that make one have increased response to drug
- intermittent use
- stimulant drugs
- effect on behavioural aspects
Why might a novel environment be a common component of a story of overdose?
- info from environment helps us prepare for drug use
- interaction b/w cues from environment & drug-taking experience
