OPIOIDS

Question 1

what are opioid drugs, what do they do

Answer 1

narcotic analgesics

reduce pain without producing unconsciousness

Question 2

main ingredient in opium

Answer 2

morphine

Question 3

how was heroin made

Answer 3

adding two acetyl groups to morphine, making it more lipid soluble

Question 4

what are the benefits of heroin + mechanisms of action

Answer 4

reaches the brain faster
more potent than morphine
carrier molecule, acetyl groups cleave off when in brain.

Question 5

opioid drugs bind to specific receptors in the ____, discovered using ________

Answer 5

brain, radio ligand assays

Question 6

4 types of opioid receptors

Answer 6

mu, delta, kappa, NOP-R

Question 7

what type of receptor are opioid receptors

Answer 7

G-protein linked metabotropic receptors

Question 8

mu receptor has _____ affinity for _____

Answer 8

high, morphine

Question 9

which areas cause analgesia due to mu receptor (5 areas)

Answer 9

medial thalamus, periaqueductal gray, raphe, locus coeruleus, spinal cord

Question 10

Brainstem mu receptor binding causes what

Answer 10

cardiovascular/respiratory control, cough control, nausea/vomitting

Question 11

sensorimotor integration mu receptor locations

Answer 11

thalamus, striatum

Question 12

NAc Mu receptor effect

Answer 12

feeding, positive reinforcement , pleasurable aspects of fatty/sweet foods.

Question 13

S (delta receptor) location

Answer 13

forebrain structures

Question 14

delta receptor roles

Answer 14

olfaction, motor integration, reinforcement and cognitive function and overlap with mu receptors suggest modulation of analgesia.

Question 15

K-(kappa) receptors location

Answer 15

striatum, amygdala, hypothalamus

Question 16

kappa receptor role

Answer 16

regulation of pain perception, gut motility, and dysphoria

Question 17

FQ receptors location + function

Answer 17

wide distribution (cortex, limbic areas, thalamus, raphe nuclei, spinal cord)
Does not bind opioid drugs
lowers pain thresholds
role in feeding, learning, motor function, reward and neuroendocrine regulation

Question 18

first peptide transmitter that binds to opioid receptors

Answer 18

enkephalin

Question 19

another endogenous peptide that binds to opioid receptors

Answer 19

endorphins

Question 20

how are endogenous opioid receptors synthesized

Answer 20

you synthesize them at the cell body, at the nucleus where the DNA and ribosomes are. Usually larger precursor peptides that are cleaved to smaller transmitters

Question 21

mu receptors are preferentially activated by

Answer 21

endorphins and selectively activated by endorphins

Question 22

delta receptor preferentially activated by

Answer 22

enkephalins and endorphins

Question 23

kappa receptor preferentially activated by

Answer 23

dynorphins

Question 24

Three ways opioids inhibit neural activity

Answer 24

1. post synaptic inhibition - receptors activate a G protein that opens k+ channels. hypolarized.
2. axoaxonic inhibition - heteroreceptors (presynaptic)- activate G proteins that close Ca2+ channels, reducing transmitter release.
3. Presynaptic autoreceptors - reduce release of co-localized NT.

Question 25

all opioid receptors are coupled to ____ that inhibit ______

Answer 25

GI proteins, adenylyl cyclase-cAMP

Question 26

Partial agonist of opium

Answer 26

buprenorphine

Question 27

``` pure antagonists (2) of opium have high ____, low ____ for receptors ```

Answer 27

naloxone, naltrexone | high affinity, low efficacy

Question 28

what do endogenous opioids and opioids do in relation to pain when they bind receptors

Answer 28

inhibit pain signal transduction at multiple sites

Question 29

spinal cord (spinal analgesia)

Answer 29

opioid interneurons can inhibit. pain projection neurons do so by activating descending pathways from brain to spine either by 1. inhibit pain projection neurons 2. inhibit excitatory interneurons that synapse on pain projection neurons

Question 30

opioids activate two descending pain-inhibiting pathways originating in the ___

Answer 30

PAG

Question 31

what do opioid projections from PAG do

Answer 31

disinhibit raphe (5HT) and locus coeruleus (NE) descending projections that suppress pain signals in the spinal cord

Question 32

what do low doses of opioids provide

Answer 32

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

Question 33

what do high doses of opioids provide

Answer 33

abnormal state of elation or euphoria

Question 34

what do highest doses of opioids cause

Answer 34

unconsciousness and death which happens due to suppression of brainstems respiratory centre

Question 35

how do we therapeutically administer opioids

Answer 35

intra-muscularly, orally (slow absorption not as euphoric)

Question 36

how do we recreationally administer opioids

Answer 36

more rapid means such as inhalation, snorting, sub-cutaneous, IV

Question 37

Aversive effects of opioids (4)

Answer 37

dysphoria, anxiety, nausea, restlessness | reduced GI motility hence constiption

Question 38

IV administration of opioids lead to which risks

Answer 38

infection collapsed veins liver/kidney damage

Question 39

opioids activate ________ and this contributes to

Answer 39

mesolimbic DA pathway, opioid reinforcement

Question 40

Mu-receptor activation does what in relation to DA

Answer 40

inhibit GABA neurons in VTA, which disinhibit DA neuron firing, increasing DA release

Question 41

Tolerance of which effects develop quickly, and which develop more slowly

Answer 41

analgesia/pleasurable tolerance = quick | constipation/pupilary dilation = slow

Question 42

withdrawal of opioid drugs symptoms

Answer 42

depress CNS function, rebound hyperactivity.

Question 43

opioid antagonist can

Answer 43

precipitate withdrawal symptoms

Question 44

opioid antagonist in _____ or _____ trigger physical withdrawal

Answer 44

Locus coeruleus or PAG

Question 45

opioid antagonist in _____ or _____ trigger aversive emotional effects withdrawal

Answer 45

NAc and Amygdala

Question 46

Methadone is what

Answer 46

opioid agonist, taken orally can help prevent severe withdrawal symptoms