Opioids

Question 1

enkephalin preferred receptor

Answer 1

delta

Question 2

endorphin and endomorphin preferred receptor

Answer 2

mu

Question 3

dynorphin preferred receptor

Answer 3

kappa

Question 4

nociceptin preferred receptor

Answer 4

NOP-R

Question 5

neuropeptide synthesis

Answer 5

1. synthesized and packaged into vesicles at cell body
2. propeptides cleaved into smaller peptides along axon terminal

Question 6

3 types of activation of opioid receptors

Answer 6

postsynaptic inhibition
- opening K+ channels: hyperpolarization

axoaxonic inhibition
- closing of Ca2+ channels: decrease release of NT

presynaptic autoreceptors
- both

Question 7

Opioid drugs

Answer 7

• narcotic analgesic
• pain reduction
• decrease gastric activity
• anti-tussive

Question 8

Opitate drugs

Answer 8

• narcotic analgesics
• conscious reduction of pain
• sense of relaxation
• euphoria
• coma, death
• decrease gastric activity

Question 9

Opiate drug differences

Answer 9

• bioavailability (lipid solubility)
• affinity of receptor (binding kinetics)
• efficacy of receptor

Question 10

What is substitution therapy?

Answer 10

• treatment of opiate disorder
• use drugs with igher affinity and low efficacy
• prevents withdrawal
  -prevents high
• slow onset, long half life
• better safety profile

Question 11

examples of substitution therapy

Answer 11

• oral methadone
• oral buprenorphine

Question 12

Locations where neuropeptides are made

Answer 12

brain
spinal sord
peripheral ANS
pituitary gland: beta-endorphin

Question 13

Characteristics of Fentanyl

Answer 13

• high bioavailability
• high efficacy
• high affinity
• could have rapid method of administration
• poor control of dosing outside medical context

Question 14

Pathway responsible for pain in brain

Answer 14

spino thalamic

early pain:
PVT –> primary and secondary somatosensory cotrex

late pain:
PAD –> PVT :
- secondary somatosensory cortex
- anterior cingulate cortex
- limbic system

Question 15

Why are opiates good painkillers

Answer 15

they are present at multiple places in pain processing circuits

Question 16

what are the 3 pain processing circuits for opiates on pain receptors

Answer 16

1. Spinal Cord
   opiates inhibits incoming pain signals
2. Brain
   opiates activate descending pathway that inhibits spinal cord activity
3. Brain
   opiates inhibit activity within brain regions (supraspinal pain modulation)

Question 17

how does cingulate cortex activity change with pain perception

Answer 17

cingulate activity decreases with painkillers

Question 18

How do opiates produce a reward feeling?

Answer 18

Activation of mesolimbic DA circuitry
- disinhibition of VTA DA neurons by endorphins = DA release in VTA

Question 19

How to check for rewarding Properties of Opiates

Answer 19

• will be self-administered
• will condition a place preference
• will decrease intracranial self-stimulation thresholds (needs less effort to trigger reward center in brain)

Question 20

What are the 4 types of tolerance?

Answer 20

1. Acute
2. Metabolic
3. Pharmacodynamic
4. Behavioral

Question 20

Describe acute tolerance

Answer 20

adapt to a drug very quickly, often within a single dose

Question 21

describe metabolic tolerance

Answer 21

reduced drug effect due to more efficient metabolism

Question 22

describe pharmacodynamic tolerance

Answer 22

reduced drug effect due to decrease responsiveness of CNS receptors

Question 23

describe behavioral tolerance

Answer 23

reduced drug effect due to expression of learned compensatory behaviors

Question 24

Why does tolerance develop?

Answer 24

decrease opioid receptor sensitivity decrease number of receptors

Question 25

What are the pharmacodynamic changes from repeated dosing

Answer 25

ongoing turnover process of new receptors number and sensitivity affect how easily a drug effects them

Question 26

What can repeated dosing trigger?

Answer 26

opponent process / compensatory regulation of activities normally inhibited by opioid receptor stimulation (homeostasis-like mechanism)