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Cerebrospinal fluid norepinephrine and acetylcholine concentrations during acute pain
J C Eisenach1, D J Detweiler, C Tong
1Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, NC 27157-1009, USA.
Anesthesia and Analgesia
|March 1, 1996
Summary
Painful stimulation activates spinal norepinephrine and acetylcholine release in sheep, suggesting a pain-relief mechanism. This noradrenergic-cholinergic pathway shows weak correlation in humans during labor.
Area of Science:
- Neuroscience
- Pharmacology
- Pain Research
Background:
- Spinal norepinephrine (NE) release is induced by painful stimuli in animals, leading to acetylcholine (ACh) release and analgesia.
- The interplay between NE and ACh in pain modulation requires further investigation.
Purpose of the Study:
- To investigate the relationship between NE and ACh in cerebrospinal fluid (CSF) during painful stimulation in sheep and humans.
- To determine if spinally released NE triggers ACh release via alpha(2)-adrenoceptors.
Main Methods:
- CSF sampling in anesthetized sheep during electrical nerve stimulation.
- Intrathecal administration of idazoxan or saline in sheep to block alpha(2)-adrenoceptors.
- CSF sampling in women during labor pain and in non-painful controls.
Main Results:
- Painful stimulation in sheep significantly increased CSF NE and ACh levels.
- Intrathecal idazoxan administration blocked the NE and ACh increase in sheep.
- While mean CSF NE and ACh levels did not differ between laboring and non-laboring women, a significant correlation between NE and ACh was observed only in women experiencing pain.
Conclusions:
- Data in sheep support the activation of spinal noradrenergic-cholinergic systems in response to pain.
- Evidence for this pain-activated pathway in humans during labor is limited, despite a correlation between NE and ACh in painful labor.