Pain and analgesics first half of 2 Flashcards
Where does peripheral sensitisaiton occur?
The primary nociceptive neurons (in the skin etc)
Where in the spinal cord is the first synapse?
Most dorsal aspect (lamina 1 or lamina 2)
Which NTs are released from the nociceptive neurons in the spinal cord?
Mostly glutamate, also some substance P and a little amount of GCRP
What is CGRP?
Calcitonin gene related peptide
Which receptors does glutamate activate?
AMPA and NMDA
Which receptor does substance P activate?
NK-1 receptor
What type of receptor is NK-1?
GPCR
Why is a fast slow time course observed in glutamate transmission?
AMPA are fast and NMDA are slow
Which second messenger does NK-1 release?
Gq
What does Gq second messenger do regarding PIP2?
Breaks down PIP2 into Diacylglycerol (DAG) and inisitol triphosphate (IP3)
What does inositol triphosphate do?
Activates calcium stores which leads to an increase in intracellular Ca2+ concentrations
What does DAG do?
Activates protein kinase C
What does Gq second messenger do regarding ion channels?
Activate Na+, Ca2+ entry ion channels and inhibit K+ exit ion channels–> more depolarisation
What happens if there is a burst of activity from the presynaptic neuron in the spinal synapse part of the pain pathway?
The synapse increases in strength over time (i.e. after 11th AP the postsynaptic response is bigger than previous)
What is synaptic plasticity?
The strength of a synapse changes over time
Why does the spinal synapse become more sensitive over time?
NMDA receptors and NK-1 receptors
How is it known that NMDA receptors affect synaptic plasticity?
Synaptic plasticity does not occur with AP5 (NMDA agonist) present
How is it known that NK-1 receptors affect synaptic plasticity?
Synaptic plasticity does not occur with SP antagonist (NK-1 antagonist) present
Where in the nociceptive pathway do inhibitory interneurons attach?
The dorsal horn projection neuron
How are inhibitory interneurons activated in the pain pathway?
Offshoots of mechanoreceptors that are in the spinal cord can activate inhibitory interneurons
What type of neurons activate inhibitory interneurons in the pain pathway?
Glutamatergic
What is nursing the injury?
Touching an injured part of the body
Why do we “nurse an injury”?
Touching it activates mechanoreceptors which can cause inhibitory interneurons to be activated, thus inhibiting the pain
What is TENS?
Transcutaneous electrical nerve stimulation–>An electrical pack that stimulates touch receptors on the skin
