Elsevier

Peptides

Volume 18, Issue 2, 1997, Pages 287-292
Peptides

Neuropeptide FF in the Rat Spinal Cord During Carrageenan Inflammation

https://doi.org/10.1016/S0196-9781(96)00287-2Get rights and content

Abstract

Kontinen, V. K., A. A. Aarnisalo, J. J. IdÄNpÄÄN–HeikkilÄ, P. Panula and E. Kalso. Neuropeptide Ff in the rat spinal cord during carrageenan inflammation. Peptides 18(2) 287–292, 1997.—The role of neuropeptide FF (NPFF) in the modulation of spinal nociception was studied in rats with carrageenan inflammation in the hind paw. Normally no NPFF-ir neuronal cell bodies are found in the spinal cord. During inflammation NPFF-neurons were seen in an area receiving innervation from the inflamed hind limb, but in rats pretreated with morphine no NPFF-ir neurons were found. NPFF or IgG from NPFF immunoserum administered intrathecally had no effect in thermal and mechanical nociceptive tests. Morphine produced significant antinociception in both tests in the inflamed paw, but the effect was not modified by NPFF. These findings differ from the effects of intrathecal administration of NPFF and opioids in acute thermal tests when no inflammation is present. The role of NPFF in the modulation of nociception in the spinal cord may be markedly changed during acute inflammation.

Section snippets

Animals

Male Sprague–Dawley rats (Bkl:SD, B&K Universal Ab, Sollentuna, Sweden) weighing 250–300 g were used. Lab chow and water were available ad lib. Rats were housed in artificial lighting with a fixed 12-h light-dark cycle. There were 5 to 7 rats in each study group. Guidelines for animal research by local authorities and IASP [34]were adhered to and the research protocol was approved by the respective institutional ethics committees.

Carrageenan Inflammation

The rats were anesthetized with enflurane and λ-carrageenan

Inflammation

The injection of carrageenan into the hindpaw produced a significant increase of the paw weight F(2, 18) = 223, p < 0.001 due to the inflammation. Morphine pretreatment significantly (p < 0.001) reduced the inflammation , but there was still a significant difference (p < 0.001) between the morphine treated rats and the non-inflamed control rats.

Immunofluorescence Studies

The distribution of NPFF-ir fibers and terminal-like thickenings in the spinal cord levels Th2–Th4, L3–L6 and S 1 in the control group rats was the same

Discussion

The role of neuropeptide FF in the modulation of spinal nociception is enigmatic. Neuropeptide FF-ir neuronal cells have been found in the dorsal laminae of the spinal cord but also deeper in lamina X [1] 12. Rhizotomy did not change the NPFF-

ir in the dorsal horn [1]and descending NPFF containing tracts have not been visualized, either 1, 12. Therefore, it seems probable that NPFF exists mainly in interneurons. NPFF could act as a modulator of nociception at the spinal level as previous

Acknowledgements

This study has been financially supported by The Academy of Finland (E.K., P.P.), Sigrid Juselius Foundation (P.P.) and a grant from Farmos Research, Finland.

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