Lecture 24- Opiates

Question 1

What do endorphins do?

Answer 1

• brain’s own natural pain-relief system
• mimic opiates effects: pain relief, pleasure, stress-relief

Question 2

When are endorphins released?

Answer 2

following exercise and certain injuries

Question 3

What does acupunture do?

Answer 3

• may relieve pain by releasing endorphins
• naloxone blocks acupuncture-induced analgesia

Question 4

Placebos

Answer 4

may release endorphins as Naloxone blocks placebo-induced analgesia

Question 5

Opiate effects on the brain- neurobio

Answer 5

• mimic action of endogenous opiod peptides (endorphins) at opiod receptors (are agonists)
• directly affects neuronal activity, intrinsic pain-modulating circuitry, additional therapeutic effects

Question 6

Opiod system is prominent in…

sensory role

Answer 6

inhibiting responses to painful stimuli

Question 7

Opiod system is prominent in…

modulatory role

Answer 7

gastrointestinal, endocrine and autonomic functions

Question 8

Opiod system is prominent in…

emotional role

Answer 8

rewarding and addicting properties of opiods

Question 9

Opiod system is prominent in…

cognitive role

Answer 9

modulating learning and memory

Question 10

Opiod major receptor subtypes

mu (u)

Answer 10

endorphin (agonist)

Question 11

Opiod major receptor subtypes

delta (δ)

Answer 11

enkephalin (agonist)

Question 12

opiod major receptor subtypes

kappa

Answer 12

dynorphin (agonist)

Question 13

What type of receptors are opiod receptors?

Answer 13

metabotropic (g-coupled)

Question 14

What do opiod receptors do in terms of neuronal action potentials?

Answer 14

• inhibits excitability
• activation of K+ channels
• inhibits voltage-activated Ca2+ channels
• inhibits NT release

Question 15

Opiates pharmacological effects

Answer 15

• euphoria- drowsiness, body warmth, “heavy” limbs
• analgesia (pain relief)
• sedation (including mental clouding)
• reduced anxiety
• depression of respiration
• cough suppression
• pupillary constriction (miosis)
• nausea/vomiting
• constipation
• impotence (loss of desire)
• vivid dreams

Question 16

Opiates actions on pain signaing

Answer 16

• possible direct actions of opioids on peripheral tissue
• inhibition occurs at spinal cord
• possible site of action in diencephalon

binds to gaba-tropic interneuron at MOR receptor in spinal cord

Question 17

Opiates’ actions on the reward pathway

Answer 17

• inhibit gaba and NAc

Question 18

Opiate tolerance -why?

Answer 18

• more drug is needed to achieve the same effects due to decreased receptors, increased liver enzymes, and conditioned tolerance

Question 19

Opiates withdrawal

Answer 19

• appear after 1-2 weeks of chronic use
• depression, crying
• high anxiety, irritability
• panting
• diarrhea

Question 20

Why is the relapse rate for opiates so high?

Answer 20

• environmental factors and Pavlovian effects
• Vietnam veterans: 21% addiction rate by end of war, but low relapse rate due to different environment at home

Question 21

reinforcement opiates

Answer 21

there is a switch from positive to negative reinforcement- avoiding withdrawal effects

Question 22

When can negative symptoms arise?

Answer 22

• around 6-12 hours after last dose
• almost flu-like symptoms