The Bulletín of Kanagawa Dental College

Vol. 36 No. 2       September- 2008

ISSN: 0385-1443      UBIC: 65

ABSTRACT

In the present study, we evaluated oxidative stress in the temporomandibular joint (TMJ) using an in vivo L-band electron spin resonance (ESR) technique. The TMJ arthritis was experimentally induced in rats with injections of rat recombinant IL-β or TNF-α in the TMJ. We used a 3-carbamoyl-2, 2, 5, 5-tetramethylpyrrolidine-1-yloxy (C-PROXYL) as a nitrooxicie spin probe, and measured the signal decay rate of C-PROXYL in the TMJ region using an Lband ESR. The results showed that the decay rates of C-PROXYL noninvasively measured with an L-band ESR in cytokine induced arthritic TMJ groups were much higher than those in the control group. We also found that the decay rate of the IL-β-injected arthritic group was much faster than that of the control and the TNF-α-injected groups at 12h post injection. Whereas the decay rate of the TNF-α-injected arthritis group was much faster after 48h postinjection than that of the control and the IL-β-injected groups, the decay rates of both the IL-β and TNF-α groups were at the same level after seven days post-injection. These results may imply that IL-1β is capable of inducing inflammatory changes as well as of producing reactive oxygen species (ROS) more rapidly than TNF-α in rat TMJ, but these changes are transient and they had recovered by the seventh day after the cytokine administration. Thus, we were able to measure the fine changes in oxidative stress caused by ROS in the cytokine induced rat TMJ arthritis using an L-band ESR. With further advancement in in vivo ESR techniques, this technology holds great promise for the noninvasive assessment of oxidative stress in temporomandibular disorders (TMD). Key words: Temporomandibular joint (TMJ) / Oxidative stress / Reactive oxygen species (ROS) / IL-β, TNF-α L-band electron spin resonance (ESR).

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