IADR Abstract Archives
Involvement of Satellitecells in TG following TMJ Inflammation
Objectives: In clinical practice, it is well known that patients suffering from temporomandibular joint (TMJ) disorders sometimes complain of masseter muscle pain. It is considered that there is some sort of involvement between TMJ disorders and masseter muscle pain.
However, the underlying pathophysiology in such pain is still unknown. Recently, activated satellite cells in the trigeminal ganglion (TG) are known to contribute pain modulation. In the present study, we investigated the involvement of activated satellite cells in masseter muscle pain associated with
TMJ inflammation induced by complete Freund's adjuvant (CFA) injection.
Methods: CFA was injected into the unilateral TMJ, and a daily passive opening and closing jaw movement (1Hz, 30 min/day) was performed under deep anesthesia. The head-withdrawal thresholds (HWTs) to mechanical pressure applied to the TMJ and masseter muscle.
On day 3, the surface temperature of the TMJ and MM measured by thermography.
In advance , retrograde labeling tracer Fluoro gold (FG) was administrate into the MM and the number of FG-labeled and encircled with GFAP TG neurons was counted.
Results: The head-withdrawal thresholds (HWTs) to mechanical pressure applied to the TMJ and masseter muscle were significantly reduced on day 3 after CFA injection, and the reduction of HWTs were lasting for 14 days. On day 3, the surface temperature of the TMJ significantly increased. In addition, the number of TG neurons innervating masseter muscle which were encircled with glial fibrillary acidic protein immunoreactive cells significantly increased.
Conclusions: The present findings suggest that satellite cells encircling TG neurons innervating masseter muscle are activated by TMJ inflammation and the TG neuronal excitability is enhanced attributable to the satellite cell activation, resulting in masseter muscle pain spread.
However, the underlying pathophysiology in such pain is still unknown. Recently, activated satellite cells in the trigeminal ganglion (TG) are known to contribute pain modulation. In the present study, we investigated the involvement of activated satellite cells in masseter muscle pain associated with
TMJ inflammation induced by complete Freund's adjuvant (CFA) injection.
Methods: CFA was injected into the unilateral TMJ, and a daily passive opening and closing jaw movement (1Hz, 30 min/day) was performed under deep anesthesia. The head-withdrawal thresholds (HWTs) to mechanical pressure applied to the TMJ and masseter muscle.
On day 3, the surface temperature of the TMJ and MM measured by thermography.
In advance , retrograde labeling tracer Fluoro gold (FG) was administrate into the MM and the number of FG-labeled and encircled with GFAP TG neurons was counted.
Results: The head-withdrawal thresholds (HWTs) to mechanical pressure applied to the TMJ and masseter muscle were significantly reduced on day 3 after CFA injection, and the reduction of HWTs were lasting for 14 days. On day 3, the surface temperature of the TMJ significantly increased. In addition, the number of TG neurons innervating masseter muscle which were encircled with glial fibrillary acidic protein immunoreactive cells significantly increased.
Conclusions: The present findings suggest that satellite cells encircling TG neurons innervating masseter muscle are activated by TMJ inflammation and the TG neuronal excitability is enhanced attributable to the satellite cell activation, resulting in masseter muscle pain spread.