BackgroundAuditory hypersensitivity is one of the major complications in autism spectrum disorder. The aim of this study was to investigate whether the auditory brain center is affected in autism model rats. MethodsAutism model rats were prepared by prenatal exposure to thalidomide on embryonic day 9 and 10 in pregnant rats. The superior olivary complex (SOC), a complex of auditory nuclei, was immunostained with anti-calbindin d28k antibody at postnatal day 50. ResultsIn autism model rats, SOC immunoreactivity was markedly decreased. Strength of immunostaining of SOC auditory fibers was also weak in autism model rats. Surprisingly, the size of the medial nucleus of trapezoid body, a nucleus exerting inhibitory function in SOC, was significantly decreased in autism model rats. ConclusionsAuditory hypersensitivity may be, in part, due to impairment of inhibitory processing by the auditory brain center.