Activation of trigeminal intranuclear pathway in rats with temporomandibular joint inflammation.
We examined the anatomical connections of trigeminal neurons between the trigeminal subnuclei interpolaris/caudalis (Vi/Vc) transition and caudal subnucleus caudalis/upper cervical dorsal horn (Vc/C(1,2)) zones in rats, using the fluorogold (FG) retrograde tracing method combined with Fos expression, a marker of neuronal activation, following temporomandibular joint (TMJ) inflammation. The head withdrawal threshold was also measured in rats 3 days after complete Freund's adjuvant (CFA)-induced TMJ inflammation. The head withdrawal threshold on the inflamed side was significantly decreased after CFA injection into the TMJ. FG was injected into the Vi/Vc transition zone and retrogradely labeled FG-positive cells were observed in the Vc/C(1,2) region. Numerous Fos protein-expressing cells were present both in the Vi/Vc transition zone and in the laminated Vc/C(1,2) zone. A population of cells was double-labeled with Fos and FG in the Vc/C(1,2) zone. Fos/FG cells were only observed in the deep laminae of the Vc/C(1,2) zone. These findings suggest that Vi/Vc transition zone activity is modulated by activation of the caudal laminated zone after orofacial tissue injury.
Sato
Takako
T
Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan.
Kitagawa
Junichi
J
Ren
Ke
K
Tanaka
Hiroshi
H
Tanabe
Aya
A
Watanabe
Tatsuhisa
T
Mitsuhashi
Yutaka
Y
Iwata
Koichi
K
D000704:Analysis of Variance; D000818:Animals; D001169:Arthritis, Experimental / Q000503:physiopathology*; D005456:Fluorescent Dyes; D005620:Freund's Adjuvant; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009619:Nociceptors / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology*; D014275:Trigeminal Caudal Nucleus / Q000166:cytology / Q000503:physiopathology*; D000099169:Fos-Related Antigen 1
D005456:Fluorescent Dyes; D005620:Freund's Adjuvant; D016760:Proto-Oncogene Proteins c-fos; D000099169:Fos-Related Antigen 1