Facilitation of spinal morphine analgesia in normal and morphine tolerant animals by neuropeptide SF and related peptides
Abstract
Neuropeptide FF and related synthetic amidated peptides have been shown to elicit sustained anti-nociceptive responses and potently augment spinal anti-nociceptive actions of spinal morphine in tests of thermal and mechanical nociception. Recent studies have described the occurrence of another octapeptide, neuropeptide SF (NPSF) in the spinal cord and the cerebrospinal fluid and demonstrated its affinity for the NPFF receptors. This study examined the effects of NPSF and two putative precursor peptides, EFW-NPSF and NPAF, on the spinal actions of morphine in normal and opioid tolerant rats using the tailflick and pawpressure tests. In normal rats, NPSF demonstrated weak intrinsic activity but sub-effective doses of the peptide significantly increased the magnitude and duration of spinal morphine anti-nociception in both tests. A low-dose of NPSF also augmented the spinal actions of a delta receptor agonist, deltorphin. The morphine-potentiating effect of NPSF was shared by EFW-NPSF and the octadecapeptide NPAF. In animal rendered tolerant by continuous intrathecal infusion of morphine for 6 days, low dose NPSF itself elicited a significant anti-nociceptive response and potently increased morphine-induced response in both tests....Continue Reading
References
The neuropeptide FF analogue, 1DME, enhances in vivo met-enkephalin release from the rat spinal cord
Identification of neuropeptide FF-related peptides in human cerebrospinal fluid by mass spectrometry
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