Separate and combined effects of a benzodiazepine (alprazolam) and noise on auditory brainstem responses in man

Auditory brainstem responses (ABRs) were recorded in 60 male or female, anx ious or anxiety-free university students, before and after separated or sim ultaneous intake of alprazolam and exposure to noise. A significant increas e of the latencies of the ABRs was found when subjects took alprazolam. Thi s effect is consistent with the presence of gamma-aminobutyric acid (GABA), one of the neurotransmitters at terminals of cochlear efferent fibres A si gnificant increase of the latencies was observed after noise alone. In subj ects taking alprazolam when they are exposed to noise, the effect of noise on the ABR latencies is reduced. but not abolished. The effects of alprazol am on the ABR are consistent with the presence of GABA in the medulla and p uns. Significant effects of noise upon III-V and I-V intervals suggest that auditory 'fatigue' may involve a retrocochlear component. Differences due to sex appear to be abolished by anxiety.