Temporomandibular disorder (TMD) is prevalent in
dental clinics and can involve problems with the
masticatory muscles or the
temporomandibular joints (
TMJ). The
pain of TMD is frequently associated with
inflammation in the TMJs, but it's etiology is considered to be multifactorial and includes biologic, behavioral, environmental, social, emotional and cognitive factors. The purpose of this investigation was to evaluate the
anxiety-like
behavior in
rats exposed to temporomandibular
inflammation via
injection of
Freund's Adjuvant (CFA) with the elevated plus maze (EPM) and
light/dark box (LDB) tests and to evaluate nociceptive
behavior with the von Frey test at different periods. Moreover, this study measured
TMJ inflammation using
plasma extravasation (
Evans blue test) and the intraarticular infiltration of polymorphonuclear
neutrophils (
myeloperoxidase quantification). The results showed that
rats that were submitted to
TMJ inflammation exhibited a decreased number of entries into the open
arms of the EPM and a decrease in the
time spent in the
light compartment and in the number of
transitions in the LDB. Additionally, the number of entries in closed
arms in the EPM, used as indicator of
locomotor activity, did not alter between
treatments. Furthermore, increases in mechanical
sensitivity and increases in
plasma extravasation in the
joint tissue occurred throughout the
inflammation process, along with an increase in
myeloperoxidase in the
synovial fluid of
TMJ. Our results suggest that the temporomandibular
inflammation induced by CFA produced
anxiety-like
behaviors in
rats and induced nociceptive
behavior across different periods of
inflammation.