lecture 13 LOs Flashcards

1
Q

what do opiod narcotic analgesics do

A

reduce pain without producing unconsciousness

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2
Q

what is the main ingredient in opium

A

morphine

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3
Q

what is heroin made of (chemical structure)

A

morphine with 2 acetyl groups added to it (making it more lipid soluble)

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4
Q

where are opioid receptors found in the body

A

in the brain (receptors found w radioligand binding) and also in the gut

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4
Q

what are endogenous opioid receptor subtypes

A

mu, delta, kappa, and the nociceptin/orphanin FQ receptor (aka NOP-R)

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5
Q

what type of receptors are found in the endogenous opioid system

A

g protein linked metabotropic receptors

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6
Q

mu receptor has high affinity for what

A

morphine

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7
Q

what does the regional distribution of mu mean regarding its effects

A

periaqueductal grey: analgesia
brain stem: cardiovascular/respiratory control, cough control, vomiting
thalamus: sensorimotor integration
NAc: feeding, positive reinforcement

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8
Q

where is the delta endogenous opioid found

A

predominantly in the forebrain structures
suggests roles in olfaction, motor integration, reinforcement, cognitive function
reduced activity causes anxiety

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9
Q

kappa receptors have distribution to where

A

striatum, amygdala, hypothalamus
may play a role in pain perception, fut motility, dysphoria

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10
Q

what does NOP do

A

does not bind to opioid drugs
role in analgesia, feeding, learning, motor function, reward and neuroendocrine regulation
NOP agonists have minimal abuse potential and cause less respiratory depression

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11
Q

what are endorphins

A

peptides that activate opioid receptors

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12
Q

what are endogenous opioid peptides synthesized from

A

larger precursor peptides then cleaved to smaller peptide transmitters

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13
Q

what type of amino acid sequences do propeptides have

A

for both endogenous opiates and other transmitters

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14
Q

what are two ways that opioid transmitters can be released

A

via long axonal projection systems, or by local circuit neurons

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15
Q

are endogenous opioids selective

A

no, they show a relative preference

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16
Q

what are mu receptors preferentially activated by

A

endorphins and somewhat by endomorphins

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17
Q

what are delta receptors preferentially activated by

A

enkephalins and endorphins

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18
Q

what are kappa receptors preferentially activated by

A

dynorphins

19
Q

how do opioids inhibit neural activity via postsynaptic inhibition

A

receptors activate a G protein that opens K+ channels

20
Q

how do opioids inhibit neural activity via axoaxonic inhibition - heteroreceptors

A

activate G proteins that close Ca2+ channels, reducing transmitter release

21
Q

how do opioids inhibit neural activity via presyanptic autoreceptors

A

reduce release of a co-localized neurotransmitter

22
Q

all opioid receptors are coupled to ____ that inhibit ____

A

G proteins, adenylyl cyclase-cAMP

23
Q

some modifications can produce partial agonists, what does this do

A

bind to the receptor but have less biological effect

24
Q

what is an example of an opioid receptor partial agonist and what does it do

A

buprenorphine: less potent than morphine, but also less risk of respiratory depression and dependence

25
Q

what do pure antagonists do and what are examples of them

A

naloxone or naltexone, they prevent or reverse the effect of the opioid drug use

26
Q

how does spinal cord opiates (spinal analgesia) work

A

opioid interneurons can inhibit pain projection neurons

27
Q

what are two ways that opioids can activate descending pathways to project to the spine

A

direct inhibit the pain projection neurons
inhibit excitatory interneurons that synapse on pain projection neurons

28
Q

opioids activate ___ pathways originating in the ___

A

two descending pain-inhibiting pathways, periaqueductal grey (PAG)

29
Q

what is the periaqueductal grey (PAG) rich with

A

peptides and receptors
stimulation inducese analgesia that can be attenuated by opioid antagonists

30
Q

opioid projections from PAG disinhibit what

A

serotonin and NE that suppress pain signals in spinal cord

31
Q

opioid activity in supraspinal locations mediate what

A

emotional, autonomic, and/or neuroendocrine components of pain

32
Q

therapeutic administration of opioids

A

intra-muscularly or orally, slower absorption, not as euphoric

33
Q

recreational opioid administration

A

more rapid means like inhalation, snorting, IV

34
Q

what do low/moderate doses of opioids do

A

pain relief, constricted pupils, drowsiness, inability to concentrate, dreamy sleep

35
Q

what do high doses of opioids do

A

abnormal state of elation or euphoria

36
Q

what pathway can opioids activate

A

mesolimbic DA, contributes to the opioid reinfocement

37
Q

what does mu receptor activation do to DA

A

inhibits GABA neurons in VTA, disinhibits DA neuron firing therefore increasing DA release

38
Q

what does kappa receptor activation do for DA

A

activation on terminals in the NAc reduces DA release

39
Q

how does the tolerance development rate differ with opioids for pleasure vs constipation

A

pleasure: tolerance develops quickly
constipation: tolerance develops more slowly

40
Q

what is the difference in the withdrawl of morphine or heroin versus methadone or burprenorphine

A

morphine: severe
methadone: less severe

41
Q

what happens when the same opioid drug is re administered or another opioid is administered during withdrawal

A

reduction i nthe symptoms (this is how methadone works)

42
Q

how can physical withdrawal symptoms be triggered

A

by opioid antagonists infused into the locus coeruleus or the PAG

43
Q

how can emotional withdrawal be triggered

A

by infusions of antagonists into the NAc or the amygdala

44
Q

what can methadone/buprenorphine (opioid agonists) by used for and what are the pros of that

A

maintenance/replacement treatments
prevents severe withdrawal symptoms and reduces cravings
cross tolerance develops so the euphoric effects of the initial drug are reduced
can produce a high if injected

45
Q

what can naltrexone (opioid antagonist) be used for and what are the pros of it

A

longer lasting naloxone, orally active
only effective for highly motivated individuals (bc drug craving is not eliminated)
less motivated addicts stop treatment and return to drug use