Inhibition of peripheral interleukin-1 beta-induced hyperalgesia by the intracerebroventricular administration of diclofenac and alpha-melanocyte-stimulating hormone.
The present study was undertaken to investigate whether or not the endogeneous mechanisms in the brain can modulate the changes in nociception produced by peripherally-administered interleukin-1 beta (IL-1 beta) in rats. We administered diclofenac and alpha-melanocyte-stimulating hormone (alpha-MSH) into the lateral cerebroventricle (LCV) 10 min before the intraperitoneal (i.p.) injection of recombinant human IL-1 beta (rhIL-1 beta, 1 ng/kg-100 ng/kg) and then observed the changes in nociception using a hot-plate test. The i.p. injection of rhIL-1 beta (10 ng/kg and 100 ng/kg) reduced the paw-withdrawal latency without affecting the colonic temperature. The maximal reduction in the paw-withdrawal latency was observed 30 min after the i.p. injection of rhIL-1 beta at 100 ng/kg. The rhIL-1 beta (100 ng/kg)-induced hyperalgesia was inhibited by the LCV injection of both diclofenac (1 ng) and alpha-MSH (100 ng). The LCV injection of either diclofenac (1 ng) or alpha-MSH (100 ng) was found to have no effect on nociception by itself. These findings therefore suggest that the hyperalgesia induced by peripheral IL-1 beta can be modulated by a cyclooxygenase pathway of the arachidonate and alpha-MSH in the brain.
Oka
T
T
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Oka
K
K
Hosoi
M
M
Hori
T
T
D000818:Animals; D001831:Body Temperature; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006930:Hyperalgesia; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D007375:Interleukin-1 / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors; D000521:alpha-MSH / Q000008:administration & dosage / Q000494:pharmacology*
D007375:Interleukin-1; D011994:Recombinant Proteins; D000521:alpha-MSH