EXPRESSION OF C-FOS-LIKE PROTEIN IN THE RAT-BRAIN AFTER INJECTION OF INTERLEUKIN-1-BETA INTO THE GINGIVA

Expression of the c-fos proto-oncogene in the rat brain was examined b y immunostaining for fos, the nuclear protein product of the c-fos gen e, after injection of interleukin-l-beta (IL-1 beta) into the gingiva of an incisor. The distribution pattern of labelled cells was compared with that induced by tooth pulp stimulation. Neurons that express fos -immunoreactivity (fos-IR) appeared in several regions in the neuraxis 1.5 h after IL-1 beta injection, peaked at 2 h, and then declined. La belled cells were found bilaterally in regions that contribute to pain -relay and pain-inhibition. The distribution of labelled cells almost matched the pattern induced by noxious tooth pulp stimulation. In indo methacin-pretreated animals, no neurons expressing fos-IR were found i n nuclei associated with relay of nociception nor in nuclei contributi ng to inhibition of nociception. The results suggest that a small amou nt of IL-1 beta at the site of periodontal disease can induce fos-IR i n brain neurons through increased prostaglandin production.