Measuring persistent temporomandibular joint nociception in rats and two mice strains

Abstract

Temporomandibular joint (TMJ) pain has been reported to last for prolonged periods in humans. In rodents a variety of methods have been used to measure TMJ nociception, but for most of these methods the period of measurement has been minutes to a couple of hours. In addition, most measurement protocols required restraint or training of the animal. Previous studies from our laboratory demonstrated that feeding behavior, particularly meal duration, was an indicator of TMJ nociception in unrestrained and untrained male and female Sprague Dawley rats for up to two days. In this study, we first found that injection of complete Freund's adjuvant (CFA) into the TMJ of rats significantly lengthened meal duration for 19 days and also decreased meal frequency for 42 days. Interestingly, the meal duration varied significantly from day to day within the 19 day period. TMJ interleukin-1β (IL-1β) and calcitonin gene-related peptide (CGRP) were significantly elevated in the TMJ tissues of CFA injected animals and the level of these markers was attenuated as the meal duration decreased with time. Control animals injected with saline into the TMJ or CFA into the knee did not show a significant lengthening in meal duration but did show a decrease in meal frequency. In a second study, DBA/1LacJ mice given TMJ CFA injections showed a significantly lengthened meal duration on four of the seven days measured using end-of-the meal definition of 5 or 10 minutes. No other meal pattern changed significantly. Two days post-CFA injection, the DBA/1LacJ mice showed significantly elevated interleukin-6 (IL-6), but not elevated IL-1β. Seven days post-injection, both IL-6 and IL-1β were significantly elevated. No change in CGRP was detected. In this study C57BL/6 mice also received TMJ CFA injections, but they did not show a lengthening in any meal pattern or significant increases in IL-1β, IL-6 or CGRP. Our data show, for the first time, that meal duration can be used to measure CFA-induced nociception in the TMJ over the course of several weeks in unrestrained rats and for up to seven days in the DBA/1LacJ mouse strain. In addition, C57BL/6 mice are resistant to CFA-induced TMJ nociception at the same dose used in the DBA/ 1LacJ mice.

Capping a Pulpotomy with Calcium Aluminosilicate Cement: Comparison to Mineral Trioxide Aggregates

“…The hydraulic cements all decreased inflammation 30 days after pulp capping a mechanical lesion. This decrease in inflammation was associated with a decrease in orofacial pain, which is consistent with previous studies (11,13–16). Future studies could determine whether a reduction in postoperative pain, an indicator of reduced pulpal damage, can be correlated to a reduction in the 30% failure rate resulting from pulp capping of mechanical lesions (32).…”

Infusion of Gabrα6 siRNA into the trigeminal ganglia increased the myogenic orofacial nociceptive response of ovariectomized rats treated with 17β-estradiol

“…Meal patterns (i.e., food intake, meal size, meal number and meal duration) were calculated using Med Assoc. Inc. and proprietary software (Bellinger et al, 2007; Guan et al, 2005; Kerins et al, 2005; Kramer and Bellinger, 2009; Kramer et al, 2010). Meal duration has been shown to be a continuous, non-invasive measure of orofacial nociception (surface and deep) in undisturbed male and female rats (Kerins et al, 2005; Kerins et al, 2003).…”

A Non-invasive Model for Measuring Nociception after Tooth Pulp Exposure

“…This model uses unrestrained rats that are continuously kept in sound-attenuated, computerized feeding modules for days to weeks to record meal patterns (Kerins et al, 2005;Kramer et al, 2010). We have shown, in male and female rats and male mice, that meal duration can be used as a non-invasive biological marker for TMJ nociception for up to 19 days in rats and 6 days in mice (Kerins et al, 2003b(Kerins et al, , 2004Bellinger et al, 2007;Kramer et al, 2010). Acute or more persistent TMJ arthritis was shown to affect the rat/mouse, such that when the animal initiated a meal, the animal ate more slowly, which significantly lengthened the A non-invasive Model for Measuring nociception after tooth Pulp Exposure meal duration.…”