How Drugs Affect our Behavior

Question 1

Receptor agonist vs agonist

Answer 1

• agonist is endogenous, receptor agonist is exogenous

Question 2

Competitive vs noncompetitive antagonists

Answer 2

• Competitive antaagonist: blocks agonists from binding to the receptors
• Noncompetitve antaagonist: bind to target receptors at a site that is different from where the endogenous ligand binds

Question 3

What does it mean to have a low affinity for a receptor?

Answer 3

• If a particular drug has a low affinity for a receptor, then it will quickly uncouple from the receptor
• To bind half the receptors at any given time, a higher concentration of the drug is needed

Question 4

What does it mean if a drug has a high affinity?

Answer 4

• the receptor and the drug will stay together for a longer time, and a lower concentration of drug will be sufficient to bind half the receptors

Question 5

What happens when there are equal concentrations of a low affinity and a high affinity drug?

Answer 5

• the high affinity drug will be bound to more receptors at any given time
• if the drugs have an equivalent effect on the receptors, then the higher affinity drug will be more potent

Question 6

What is an effective dose?

Answer 6

• The basic dose-response curve plots increasing drug doses against increasing strength of the response being studied.
• An effective dose is the dose at which the drug shows half of its maximal effect

Question 7

What is potency?

Answer 7

• Relative potencies are assessed by comparing the ED50 values
• In the example, both drugs have comparable effects, but one of the drugs has the effects at lower doses, and therefore is more potent

Question 8

What is efficacy?

Answer 8

• Drug efficacies are compared by evaluating maximal responses, rather than doses
• drug with greater maximal effect has higher efficacy

Question 9

What is a partial agonist/antagonist?

Answer 9

A drug of only moderate efficacy

Question 10

Phencyclidine

Answer 10

• PCP or Angel Dust
• NMDA receptor antagonist
• Mind altering drug that may lead to hallucinations
• Ketamine has similar effects

Question 11

NMDA Antagonists symptoms

Answer 11

• Loss of responsiveness (not consciousness)
• Loss of sense of self/identity
• Dissociation
• Psychotic thoughts
• Sensory aberrations
• Aggression and agitation (rare)

Question 12

NMDA and Schizophrenia

Answer 12

• Because NMDA receptor antagonists, such as PCP, are psychotomimetic (elicit psychotic symptoms in people), it may be reasonable to assume that NMDA receptors are naturally sub-functional in people with psychotic disorders
• If that is true, may drugs that enhance NMDA receptor function be of benefit to them?

Question 13

GABA-A Receptor

Answer 13

• Cl- channel
• Has multiple binding sites for other substances
• These are inbolved in allosteric (enzyme) regulation/modulation

Question 14

Positive allosteric modulators examples

Answer 14

• Valium
• Lunesta
• Clonazepam
• Ambiem

Question 15

Ethanol

Answer 15

• beverage alcohol
• Calming, anxiolytic, and sedative/hypnotic effects of alcohol depend upon GABA-A receptor positive modulation

Question 16

What is the dark side of positive modulators?

Answer 16

• drugs violate homeostasis
• receptor desensitization (down-regulation): fewer functional receptors=less drug-induced imhibition, doesn’t always involve fewer receptors
• tolerance

Question 17

Norepinephrine/Dopamine and ADHD

Answer 17

• All medications for ADHD influence the norepinephrine and dopamine systems
• Some block NE and/or DA reuptake via the transporter (Ritalin, Focalin, Strattera)
• Some cause NE and/or DA release (Adderall, dexedrine, vyvanse)

Question 18

Serotonine reuptake inhibitors

Answer 18

• Enable serotonin to stay in the synapse for longer
• Prozac, paxil, celexa, zoloft, luvox

Question 19

What are opioids?

Answer 19

• Ex. morphine, heroin, oxycodone, fentanyl
• Analgesic and addictive properties

Question 20

What are the three opioid receptors?

Answer 20

• delta
• kappa
• mu
• All opioids have a high affinity for mu receptors but will also bind to the others

Question 21

What are the three endogenous opioids?

Answer 21

enkephalins, endorphins, and dynorphins

Question 22

What are naloxone and naltrexone?

Answer 22

opioid antagonists used to treat alcohol use disorder

Question 23

How do opioids increase dopamine release?

Answer 23

• indirectly
• opiods bind to mu opioid receptor on GABA neuron
• when GABA is released on the GABA-A receptors on the dopamine neuron, the dopamine neuron will not fire
• When opiod is binding to GABA (blocking), GABA is not released. So, dopamine can be released easier (with no inhibition)

Question 24

What type of drug is nicotine?

Answer 24

A stimulant

Question 25

What receptor does nicotine bind to?

Answer 25

nicotinic acetylcholine receptors (nACh), calcium and sodium ion channel

Question 26

What does nicotine increase the release of?

Answer 26

• increases dopamine release
• when nicotine binds, acetylcholine is also released, leading to increased dopamine release

may also affect other neurotransmitters like norepinephrine

Question 27

What does a positive allosteric modulator do?

Answer 27

• the allosteric modification may result in enhancement in the binding affinity of the ligand with the orthosteric site causing boosting of a signal or increased activity

Question 28

What type of drug is cocaine and what does it do?

Answer 28

• stimulant
• blocks the dopamine transporter to increase the amount of dopamine available in the postsynaptic cleft (prevents dopamine reuptake, also norepinephrine and serotonin)
• allows for longer activation of the postsynaptic cell

Question 29

How do amphetamines work/what do they do?

Answer 29

• Enters presynaptic terminal via DA transporter
• Packaged into vesicles in place of dopamine
• Excess dopamine pumped out of cell via DA transporter
• Increased dopamine release into synaptic cleft (also norepinephrine and 5-HT)

reverses function of transporters allowing them to push out dopamine instead of bringing it inwards

Question 30

What type of drug is alcohol?

Answer 30

initial stimulant, prolonged depressant, sedative (unique in this range of effects)

Question 31

What receptors does alcohol act on and what does it do?

Answer 31

• Enhances GABA-A receptor activity
• reduces NMDA (glutamate receptor) activity

Question 32

Low dose alc vs High dose

Answer 32

• Low dose alcohol stimulates dopamine release- neurons are allowed to fire due to disinhibition
• At high doses, more ubiquitous action that suppresses the overall system leading to sedative effects