L216 Opiods Flashcards
Flow of pain
Nocireceptors Adelta and c fibers Trigeminal ganglion Trigeminal nuclei (not great spatial) Thalamas Limbic system and cerebral cortex
Adelta vs C fibers Speed Myelination Type of pain Stimuli
Adelta: fast, myelinated, sharp initial pain to mechanical stimuli
C fibers: Slow, unmyelinated, dull, aching, burning pain, thermal, mechanical, chemical stimuli
Tissue damage leads to the release of
Prostaglandins Substance P TNF-alpha IL 1-Beta IL-6
TRPV1 responds to this type of stimuli
Acid
Hyperalgesia
Heightened sense of pain to noxious stimuli
Allodynia
Pain resulting from normally painless stimuli
Beta endorphin is an example of this peptide
Pro-opiomelanocortin (POMC)
Three important Opioid receptors
Mu
Kappa
Delta
Mu, Kappa, Delta common charactersitics
G protein coupled receptors
Widely distributed in CNS
Activate G alpha-i
Beta endorphin is a natural agonist of
mu opioid receptor
Met-enkephalin and Leu enkephalin are natural agonists of the
delta opioid receptor
Dynorphin A
Dynorphin B
alpha/beta neo-endorphin
Are natural agonists of
Kappa opioid receptor
Proenkephalin gives off
Met enkephalin
Leu ekephalin
Prodynorphin gives off
Dyn-A
Dyn-B
alpha-neo-endorphin
Endorphins
Endormorphin-1
Endomorephin-2
Pre-synaptic mechanism of opioid receptor activity
Gi activation inhibits AC
Causing decrease cAMP
Causing decrease PKA
Cause decrease in Ca entry thru cannels
Post synaptic mechanism of opioid receptor activty
GbetaGgamma activation
Potassium leaves the cell
Hyperpolarization
Natural agonist of mu opiod receptor
B-endorphin
Physiologically important opiod receptors
U1, U2
U receptors are found in
PAG Superficial dorsal horn Nucleus accumbens Amygdala cerebral cortex
What does Mu do?
Suppresses presynaptic transmitter release
Mechanism of action of opioids with analgesic action
Opiods inhibit release of GABA which would usually inhibit the inhibitory pathway
GI effects of opiods
constipation
GI spasm
Emotional compenent of pain is from
Limbic system
