Regulation of Pain Flashcards
(24 cards)
For homeostatic control of pain, what circuit & what nucleus are used?
spino-parabrachial-amygdala circuit projects pain to parabrachial nucleus in RF
Where does the parabrachial nucleus in RF project to?
amygdala
PAG
hypothalamus & ventrolateral medulla
sympathetic activation
In relation to homeostatic control of pain, what is the amygdala for?
emotional-affective aspects of pain: anxiety, fear conditioning, antinociception, & autonomic adjustments
In relation to homeostatic control of pain, what is the periaqueductal gray (PAG) for?
defense responses & pain regulation
In relation to homeostatic control of pain, what is teh hypothalamus & venterolateral medulla for?
autonomic homeostatic adjustment
In relation to homeostatic control of pain, what is sympathetic activation for?
diversion of blood to vital organs, increased HR, BP & RR, glycogenolysis in liver & muscles, gluconeogenesis from a.a.s
Where does the PAG receive input from (directly & indirectly)? What is it involved in?
directly from ascending spinothalamic pathways
indirectly from parabrachial nucleus
involved in defense responses & supraspinal pain regulation
Defense responses produced by the PAG are regulated by what 5 brain structures?
cingulate, insula, amygdala, hypothalamus & PFC
In the PAG, what are the two zones that produce emotional coping? Which one is for active coping and which one is for passive coping?
Ventrolateral zone: passive emotional coping
Lateral zone: active emotional coping
What are the defining characteristics of the venterolateral zone? aka how will you act and what do opioids cause?
quiescence, immobility, fright/hyporeactivity
disengagement, withdrawal, inhibition of sympathetic activity
long lasting opioid mediated analgesia
What are the two divisions of the lateral zone and what kind of behavior does each produce? What are the general characteristics in terms of ANS activation and opioid effects?
rostral: confrontational zone
caudal: defensive behavior
excitation of sympathetic system
short-lasting non-opioid mediated analgesia
Homeostatic maintenance of physiologically acceptable pain is determined by what?
What is the pathway?
What is the central figure in the pain modulation/regulation pathway?
activity & sensitivity of ascending & descending pain pathways
cingulate cortex –> hypothalamus –> PAG –> reticular nuclei –> dorsal horn
PAG is central figure: responsible for stress-induced hypoalgesia
What pathway provides negative feedback on the spinal cord?
descending pathways: somatosensory, cingulate, insula, PFCs regulate amygdala, hypothalamus & PAG
PAG projects to raphe & A5,7 RF nuclei
A5,7 & raphe regulate synpase b/w sensory & spinothalamic neurons
What kind of cells make up the raphe? What are the characteristics of each?
serotonergic cells: stress-mediated, tonic inhibition of pain transmission
non-serotonergic cells: regulation of immediate pain, alerting & arousal; ON cells= pain transmission; OFF cells= inhibit pain via opioid mechanisms
What neurotransmitter comes from A5, A7? What are they for?
NE
inhibit pain transmission via alpha2 receptors
Opioids and cannabinoids do what so as to inhibit pain (what is their mechanism)?
opioid & cannabinoid action in midbrain & medulla inhibit pain by upregulating medullary raphe OFF cells
What two agonists work to help down regulate pain perception? Via what neurotransmitter?
tricyclic antidepressants & NE reuptake inhibitors enhance antinociceptive effects of opioids by increasing spinal NE
Descending ______ and _____ pathways stimulate dorsal horn _______ interneurons to inhibit spinothalamic neurons
serotonin; NE; opioid
What do opioid interneurons in the dorsal horn do?
inhibit synaptic transmission b/w pain afferent & spinothalamic neurons
decrease substance P release
down regulate substance P neurokinin-1 receptors
How do opiates work?
agonists of opioids
stimulate opioid receptors in hypothalamus, PAG & dorsal horn
What is the gate control theory?
- C fibers excite pain projection neurons: directly or by inhibiting enkephalin inhibitory interneurons
- Aalpha & Abeta inhibit C pain axons by stimulating enkephalin
- pain= descending pain control pathways inhibits Cs via presynaptic inhibition
What makes up the reappraisal-emotional matrix?
cingulate & insular cortex
-convergence of somatosensory, association cortex & ascending spinal pathways
Emotional-affective modulation of pain cognition is provided by interaction b/w what structure and what cortex?
amygdala & PFC
What does anticipating pain include and lead to? What is the placebo effect?
anticipation: cingluate & insula coordinate somatosensory features w/PFC to determine long term implications of pain; could cause anxiety
placebo: anticipated reduction of pain reinforces descending pain control from anterior cingulate, insula & dlPFC
