The use of Preyer's reflex in evaluation of hearing in mice

Preyer's reflex, the elicitation of startle response to auditory stimuli, h as been widely used for the evaluation of hearing in rodents and other anim als. Surprisingly, however, the sensitivity and specificity of Preyer's ref lex in the assessment of hearing has not been adequately studied. The aim o f this study was to investigate the utility of Preyer's reflex in the evalu ation of auditory function in mice. Forty-six adult albino mice on an FVB b ackground with variable hearing loss were used for this study. Two differen t methods for eliciting a Preyer's reflex were tested: a handclap, and a sh arp metallic sound. The reflex was considered positive when a rapid movemen t of the whole body of the animal was clearly noticed. Thereafter, the mice underwent auditory brain stem response (ABR) testing with broadband clicks . The presence or absence of Preyer's reflex was compared with the correspo nding ABR thresholds. Five of the 46 animals studied (11%) showed a negativ e Preyer's reflex, while the remaining 41 animals. demonstrated a positive Preyer's reflex. There was no difference between the abilities of the two d ifferent stimuli to elicit a Preyer's reflex. The click-evoked ABR threshol ds in the test animals varied between 8 and 136 (mean 50) dB sound pressure level (SPL). Preyer's reflex was positive in all animals with an ABR thres hold of less than or equal to 76 dB SPL, but was absent in animals with an ABR threshold of greater than or equal to 81 dB SPL. Preyer's reflex is eff ective for identifying profound sensorineural hearing loss in experimental mice, but is insensitive for detecting less severe auditory dysfunction. Fo r definitive hearing assessment, and for defining the hearing thresholds, o bjective electroacoustical methods such as ABR should be used.