Drugs and the Brain Flashcards
Chemical transmission
the steps it takes for a drug to exert its effects
steps. ..
- synthesis of NT
- Storage of the NT
- Breakdown of the cytoplasm
- Exocyst
- Autorecptor feedback on the pre-synaptic cleft
- Activation of the post-synaptic receptors by NT
- Deactivation of the NT
Define Agonist
enhance activity of neurotransmitter for which they are agnostic
-agnostic effects: accomplished by drug binding to receptor site imitating the NT that should be there
what does Nicotine do as an agonist?
What does Cocaine do?
- ex/ nicotine binds to NT Ach, binding to the nicotinic receptors producing a stimulant effect
- ex/ cocaine blocks re-uptake of NT by pre-synaptic neuron causing DA and NE to hang around
Define Ant-agnostic
diminish or decrease neurotransmitter activity
- accomplished by drug binding to NT site and blocking NT that should be there but having no effect
- prevent appropriate NT from getting in
How does Curare and Botox effect NT’s
How does Botulinum toxin effect NT’s (both ant-agnostic)
Curare and Botox:
antagonists for the NT Ach and they block Nicotinic receptor site at the muscular junctions. For Botox and curare they prevent muscles from moving and cause paralyzing effects.
Botulinum Toxin: NT Ach, inhibiting release of ACh from pre-synaptic nueron thereby decreasing the amount of available ACh in those synapses and causes paralysis
What are the 6 Agnostic effects?
- drug serves ad a precursor for NT
- Drugs stimulates the release of NT
- Drug stimulates post-synpatic receptors for NT
- Drug blocks pre-synaptic autoreceptors for NT
- Drug blocks reuptake of NT
- Drug inactivates breakdown enzyme for NT
What are the 5 Antagonistic effects?
- Drug prevents storage of NT in synaptic vesicles
- Drug inhibits release of NT
- Drug blocks post-synaptic receptors for NT
- Drug inactivates synthetic enzyme for NT
- Drug stimulates autoreceptors for NT
CAPILLARIES OF THE BRAIN
- more compact tightly together, watersolluable substances cannot pass through
- only lipid-soluable substances can pass the lipid capillary wall
GLIAL CELLS
- if a substance is able to move through the capillary wall, it encounters yet another barrier
- 85% of capillaries in brain covered with glial cells resulting in very little extracellular space next to the blood vessel walls.
- very difficult to get thru blood brain barrier
- need active transport system
- some drugs enter brain through passive transport ( heroine, nicotine, alcohol) down concentration gradient from bloodstream to the brain - the extent of these drugs effect on BBB shows drugs influence on psychological process
babies and BBB
- blood brain barrier is not fully developed until 1-2 years of age
- infants exposed to drugs or alcohol have a heightened effect
- born with addictions, if exposed to drugs in womb
Define Pharmacokinetics
the movement (kinetics) of Drugs (pharmaco) -process by which dugs are absorbed, distributed in body, metabolized, and excreted
Administration of Drugs through Injection:
SUBCUTANEUOUS: Needle is inserted just under the skin
INTRAMUSCULAR: Needle inserted into a muscle (often upper arm or buttock muscle). Depot Injection is a special type of injection which the vehicle is oil, slowing diffusion of the drug in the body fluids
INTRAPERITONEAL: Needle is inserted through the abdominal wall into peritoneal cavity which is the area surrounding the intestines, liver, stomach, and other abdominal organs
INTRAVENOUS: Needle is inserted through vein, so drug moves directly into blood stream
non injection methods of drugs administration:
Oral
Intrarectal
Inhalation
Topical
Injection methods that by pass Blood Brain Barrier
INTRACEREBRAL
INTRACEREBROVENTRICULAR
INTRATHECAL
Dose response curve:
and how to use it to compare effectiveness of drug
Definition: a graph of the magnitude of a drug as function of the amount of drug administered
- compares effectiveness of different drugs and compare the dose at which 50% of subjects who receive each drug experience the effect under investigation
- (ED50=effective dose) (LD=Lethal dose)
Therapeutic Index:
the ratio between the dose that produces lethal effects in 50% of the subjects to whom it is given and the dose that produces the desired effects in 50% of the subjects to whom it is given= (LD50/ ED50). The higher the TI the safer the drug is
Potency and Efficacy
when comparing 2 drugs
Potency: refers to differences in how much of each drug must be administered to achieve the same magnitude of effect. ex/ LSD 10X more protent in its hallucinogenic effect than Lysergic Acid Amide, so therefore if using Lysergic Acid Amide then ingesting 10X the amount of this drug would produce the same effect as taking 1 LSD
Efficacy: Efficacy refers to DIFFERENCES in the MAXIMUM effect that each drug will produce
EX/ Asprine is much less effective than morphine even at it’s most effective/ highest dose, still much less effective comparably
Tolerance
when a drug loses effectiveness, user has built up a tolerance, and requires a higher dose to produce desired effect!
Represents a shift in dose response curve to the right
in
tolerance can develop to some of the effects of a drug but not other effects, so you aren’t building up your tolerance in terms of the drug itself
- example/ possible to build a tolerance to pain killing effects of drug, but not the lethal effects
- tolerance not caused by one mechanism in the nervous system, many different kinds of changes in the nervous system are responsible for many different effects of each drug
Reverse Tolerance (Sensitivity)
- A shift in the dose response curve to the left
- A smaller dose of the drug produces same magnitude of effect in the subject as larger dose did originally
-ex/ becoming tolerant to nausea effect of alcohol but more sensitive to cognitive impairment
Cross Tolerance
tolerance to one drug can result in tolerance to other drugs, because similar mechanisms of action
Withdrawal
- physiological symptoms that occur when the use of the drug is stopped or decreased
- typically opposite of the effects of taking the drug itself.
Methadone
-A heroin Agonist. Exerts its effect by blocking the opiate receptor sites
Naltrexone
An opioid Antagonist
