Opiates modify induction of c-fos proto-oncogene in the spinal cord of the rat following noxious stimulation.
The expression of the proto-oncogene c-fos in neurons of the spinal cord dorsal horn of the rat following noxious thermal stimulation was compared in morphine- and ketamine-treated animals. Intravenous injection of morphine reduced the number of c-fos-positive neurons by up to 85% in laminae III-VI and X. This effect was dose dependent and naloxone reversible. The non-competitive N-methyl-D-aspartate (NMDA) antagonist ketamine had no effect. The present data show that morphine suppresses the induction of c-fos. A block of Ca2+ influx through voltage- and ligand (NMDA)-gated channels does not influence c-fos protein synthesis in the dorsal horn of the spinal cord in vivo.
Tölle
T R
TR
Clinical Neuropharmacology, Max-Planck-Institute for Psychiatry, Munich, F.R.G.
Castro-Lopes
J M
JM
Coimbra
A
A
Zieglgänsberger
W
W
D000818:Animals; D007150:Immunohistochemistry; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism* / Q000503:physiopathology
D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D009270:Naloxone; D007649:Ketamine; D009020:Morphine