Background and aims: Chronic orofacial pain conditions affect the trigeminal system, resulting in neuronal plasticity, leading to patients' negative affect. Studies have suggested that ultrasonic vocalizations (USVs) emitted by rats in appetitive and aversive contexts may correspond to an expression of the affective component of pain. Methods: USVs were recorded with an Ultra Sound Microphone (CM16; Avisoft Bioacoustics) and analyzed by the Avisoft software. The intraoral incision of the buccal mucosae and the constriction of the infraorbital nerve (CION) were used as models of inflammatory and trigeminal neuropathic pain, respectively. Elevated plus maze apparatus was used to determine the anxiety-like behavior. Immunostaining for c-Fos activation of rats slices was visualized using a Zeiss LSM 510 META confocal system. The analysis was carried out on day 3 after the intraoral incision or on day 15 after CION, and facial thermal or mechanical hyperalgesia was determined by using a radiant heat source or Von Frey filaments, respectively. Two-way ANOVA followed by Bonferroni post hoc test was used for statistical analysis. Results: Rats showed a reduction in the 50-kHz calls, specifically in the flat USVs, facial hyperalgesia, anxiety-like behavior and c-Fos activation in the mPFC, NAc, AMY, PAG and Sp5C. Conclusions: Persistent pain is related to impaired social interaction and mood changes. The analysis of USVs may be a useful tool to enhance the translational aspect of these models. Acknowledgements: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001.

ANALYSIS OF ULTRASONIC VOCALIZATIONS IN RATS SUBJECTED TO CHRONIC OROFACIAL PAIN MODELS