The c-fos is known as neuronal marker of second neurons which is activated by noxious peripheral stimulation. To investigate the changes of c-fos expression in the trigeminal n icleus complex during tooth movement, immunohistochemical study was performed.
Experimental rats(9 weeks old, 210 gm, 21 rats) were divided into seven groups( normal, i hour group, 3 hour group, 6 hour group, 12 hour group, 1 day group, 3 day group). Rats in the normal group were anesthesized without orthodontic force. Rats in the experimental groups-- were applied orthodontic force (approximately 30 gm) to upper right maxillary molar.
Frozen sections of brain stem were immunostained using rabbit antisera. The changes of c-fos expression were observed with respect to rostrocaudal distribution, laminar organization, and duration of orthodontic force application.
The study results were as follows
The c-fos nuclei in the dorsal part were observed from ipsilateral transition zone of subnucleus interpolaris and subnucleus caudalis to Ci cervical dorsal horn rostrocaudally. The maximal peak point was the rostral part of subnucleus caudalis. The greatest proportion of c-fos cells were located within lamina I and H.
The c-fos nuclei in the dorsal part were observed from the most caudal part of subnucleus interpolaris to the middle part of the subnucleus caudalis.
The number of c-fos imniunoreactive dot increased at 1 hour group, reached its maximum at the 3 and 6 hour groups, and showed a decreasing trend after 12 hours.
These results imply that nociceptive stimulation caused by continuous orthodontic force might be modulated by transition zone of subnucleus interpolaris and subnucleus caudalis, subnucleus caudalis, Ci spinal dorsal horn.
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