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Morphine and substance P release in the spinal cord
C R Morton1, W D Hutchison, A W Duggan
1Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T.
Experimental Brain Research
|January 1, 1990
Summary
Morphine
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Substance P (SP) is a neuropeptide involved in pain transmission.
- Opioid analgesics like morphine are commonly used for pain relief.
- The precise mechanism of morphine's action in the spinal cord remains under investigation.
Purpose of the Study:
- To investigate the effect of morphine on the release of immunoreactive substance P (irSP) in the feline spinal cord.
- To determine if morphine's analgesic action involves the modulation of SP release.
Main Methods:
- Antibody microprobes were employed to measure irSP release in anesthetized cats.
- Stimulation methods included noxious cutaneous and high-intensity nerve stimulation.
- Morphine was administered systemically and locally (superfusion) to the dorsal cord surface.
Main Results:
- irSP release was primarily detected in the substantia gelatinosa and dorsal cord surface.
- Systemic morphine did not alter irSP release.
- Local superfusion of morphine caused a slight reduction in irSP release in the substantia gelatinosa, but not at the surface.
Conclusions:
- Morphine's analgesic effects do not appear to be mediated by a reduction in spinal substance P release.
- The findings suggest alternative mechanisms for morphine's action in pain pathways.