Tooth pulp stimulation induces c-fos expression in the lateral habenular nucleus of the cat
Matsumoto, N.; Yahata, F.; Kawarada, K.; Kamata, K.; Suzuki, T.A.
Neuroreport 5(17): 2397-2400
ISSN/ISBN: 0959-4965 PMID: 7881067 DOI: 10.1097/00001756-199411000-00046
Detection of Fos protein expression by the peroxidase-antiperoxidase method was used to determine the area in the habenular (Hb) complex responding to electrical stimulation of the tooth pulp in the cat anaesthetized with pentobarbital. In the anaesthetic-injected group, the Fos-positive neurones were found bilaterally in the lateral Hb nucleus (HbL). Tooth pulp stimulation (intensity: 3 times the threshold for jaw-opening reflex) increased the number of positive neurones within the HbL by up to 300%, but did not induce any expression in the medical Hb nucleus. The increase in HbL was inhibited by morphine (2 mg kg-1, i.p.). These findings and the results of previous research suggest that HbL neurones are involved in defensive mechanisms by means of antinociception following noxious stimulation.