1993 Volume 56 Issue 6 Pages 486-496
I examined the expression of enkephalin during tooth movement, which is occasionally associated with pain. Several immunohistochemical studies have recently shown the expression of peptides related to neurotransmission in central and peripheral tissues. Enkephalin, which acts as an analgesic, has received much attention.
Male Wistar rats, weighing 200 to 250 g, were killed at 1, 3, 6, 9, 12, 18 and 24 hours, and 2, 7 and 14 days after insertion of elastic bands between the upper left first and second molars (Waldo's method). The first molars with surrounding structures were decalcified and sectioned at 15 μm in a cryostat. The sections from the right maxillary molars were used as controls. All sections were stained by indirect immunofluorescence and hematoxylin-eosin. The examination concentrated on the buccal root periodontal ligament of the first molar.
Immunohistochemistry using the indirect immunofluorescence method revealed that enkephalin-immunoreactive cells were found in the periodontal ligament at 6, 9 and 18 hours after tooth movement. Particularly strong enkephalin-immunoreactivity was found at 9 hours. When the in situ hybridization method was used, signals were found in the periodontal ligament at 9 and 18 hours.
The appearance of enkephalin-containing cells in the periodontal ligament during tooth movement suggests that this chemical is associated with neurotransmission and that it can be produced by periodontal ligament cells during the movement.
