Hyperalgesia in response to traumatic occlusion and GFAP expression in rat parabrachial [correction of parabranchial] nucleus: modulation with fluorocitrate.
We have examined, by immunocytochemical methods and nociceptive behavior assessment in rats, whether astrocytes in the parabrachial nucleus (PBN) are involved in the regulation of traumatic occlusion. The expression of glial fibrillary acidic protein (GFAP) in PBN of ipsilateral and contralateral sides was up-regulated 4 h after occlusal changes in molars, reached peak levels at 24 h, and was then gradually down-regulated. PBN astrocytes activated by traumatic occlusion were found to have enlarged cell bodies and thickened processes within 8 h. An inhibitor of glia metabolism (FCA, fluorocitrate) reduced astrocyte activation and significantly attenuated the development of pain hypersensitivity in this model. The results suggested that the GFAP-immunoreactive astrocytes in PBN within the bridge of Varolius were activated by traumatic occlusion, and that they were involved in the transmission and modulation of nociceptive information in the central nervous system. However, although astrocytes in PBN are thus probably involved in causing post-occlusal hyperalgesia, we have not been able to exclude that astrocytes at other locations also contribute to this effect.
Chen
Jinwu
J
Department of Oral Radiology and General Dentistry, School of Stomatology, Fourth Military Medical University, Xi'an, 710032, People's Republic of China. jinwuechen@yahoo.com.cn
Zhang
Jun
J
Zhao
Yimin
Y
Yuan
Lintian
L
Nie
Xin
X
Li
Jianfu
J
Ma
Zhiwei
Z
Zhang
Yongjie
Y
Wang
Qi
Q
Chen
Yongjin
Y
Jin
Yan
Y
Rao
Zhiren
Z
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D002951:Citrates / Q000494:pharmacology*; D003769:Dental Occlusion, Traumatic / Q000150:complications / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis*; D006930:Hyperalgesia / Q000209:etiology / Q000378:metabolism*; D008297:Male; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000378:metabolism*
D002951:Citrates; D005904:Glial Fibrillary Acidic Protein; C007744:fluorocitrate