pain pathways

Question 1

name the 4 types of drugs that act on nociception in the peripheral afferent fibers

Answer 1

opioids
LA
cox2 inhibitors, nsaids, aspirin
ketamine

Question 2

drugs acting on the dorsal horn

5

Answer 2

LA
cox2 inhibitors, nsaids, aspirin
ketamine 
opioids
alpha 2 agonist

Question 3

What is the path inside the PAG naming receptors that cause disinhibition and activation descending pain pathways of the raphe and LC

Answer 3

-2nd order neuron from dorsal horn release glutamate
-glutamate binds to NMDA receptor on enkephalin -
interneuron/ enkephalin released
-enkephalin binds to Mu/Gi receptor on GABA interneuron stopping release of GABA
-Glutamatergic neuron of descending disinhibited/fires down to raphe and LC

Question 4

sodium gates channels cause erythromelalgia (burning pain)

Answer 4

gain of function mutation

Question 5

results in congenital pain insensitivity

Answer 5

loss of function mutation

Question 6

spinothalamic projects to

Answer 6

somatosensory cortex

Question 7

trigeminothalmic tract projects to

Answer 7

somatosensory cortex

Question 8

spinoemotional tract projects to

Answer 8

thalamus
association cortex
limbic system
higher order of processing of pain

Question 9

spinoreticular tract projects to

Answer 9

RAS/locus coeruleus(pons)/Raphe magnus (medulla)

Question 10

spinomesencephalic tract projects to

Answer 10

PAG

Question 11

descending input from the amygdala (fear anxiety) tract projects to

Answer 11

hypothalamus / PAG

pituitary ( secretes ACTH & B endorphin)

Question 12

Sites of action Local anesthetics 3

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord
o Brain
o endogenous = NE (came from locus coeruleus)
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Answer 12

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord

Question 13

Sites of action NSAIDs, COX2 inhibitors, ASA- 3

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord
o Brain
o endogenous = NE (came from locus coeruleus)
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Answer 13

-Nociception afferent nerve fiber terminals
o Dorsal horn of spinal cord
o Brain

Question 14

Sites of action Opioids 4

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord
o Brain
o endogenous = NE (came from locus coeruleus)
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Answer 14

-Nociception afferent nerve fiber terminals
o Dorsal horn of spinal cord
o Brain
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Question 15

Sites of action Alpha2 agonists (dexmedetomidine) 3

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord
o Brain
o endogenous = NE (came from locus coeruleus)
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Answer 15

o endogenous = NE (came from locus coeruleus)
o Dorsal horn of spinal cord
o Brain

Question 16

Sites of action Ketamine (NMDA receptor antagonists) 4

o Nociception afferent nerve fiber terminals
o First order neurons
o Dorsal horn of spinal cord
o Brain
o endogenous = NE (came from locus coeruleus)
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus

Answer 16

-Nociception afferent nerve fiber terminal
o Dorsal horn of spinal cord
o Descending inhibitory circuits  PAG, Locus Coeruleus, Raphe Magnus
-brain

Question 17

Gabapentin target? MOA?

Answer 17

• binds to a1delta2 subunit
• decreases calcium influx, decreased NT released from nerve terminals, decreased glutamate, substance P

dorsal horn, nociceptor, brain