Abstract
To establish an experimental model of central hearing loss in the central auditory system, the auditory function (auditory brainstem response, ABR) and the histopathology of the inferior colliculus (IC) in rats in thiophene poisoning were studied. Undergoing abnormal ABR patterns at the acute stage, the lesions in the IC developed neuronal necrosis with karyolysis, pyknosis, and postsynaptic terminals, axonal swelling, and swollen astrocytic processes. Later, these abnormal features disappeared except for axonal swelling and slight gliosis. The degenerated neurons were localized characteristically in the rostral dorsomedial and medial side of caudal ventrolateral portions of the IC central nuclei, corresponding tonotopically to the high-frequency band. A morphometric study showed that mediumsized neurons were mainly involved. It is suggested that the thiophene poisoned rat could become a useful model of hearing loss in the central auditory system (IC), especially that involving the highfrequency band.
