Meal pattern analysis in response to temporomandibular joint inflammation in the rat

Inflammation of the temporomandibular joint (TMJ) can alter behavioral resp onses such as food intake and mobilize stress hormones. The hypothesis of t his study was that food intake and diurnal corticosterone analysis can be u sed as indicators of adjuvant-induced TMJ inflammation. Groups of rats rece ived adjuvant or no injections at the beginning of the resting (AM) or acti vity (PM) phase. Forty-eight hours (early) or 6 weeks (late) after adjuvant injection, plasma corticosterone was assayed and food intake was recorded. Food intake was suppressed up to 4 days post-injection. As expected, the n on-injected group showed low AM and high PM corticosterone. AM corticostero ne was elevated, but PM corticosterone was attenuated in both early- and la te-stage-injected rats. A computerized pair-fed experiment showed that adju vant-induced hypophagia did not alter corticosterone levels. Meal pattern a nalysis revealed decreased food intake due to a decrease in the number of m eals taken. Notably, meal size remained the same but meal duration increase d. This model demonstrated that food intake and stress hormone analysis cou ld be used as indicators for sequelae of adjuvant-induced TMJ inflammation.