Effects of a zinc-deficient diet on hearing in CBA mice.

This study investigated the effect of a zinc-deficient diet on the hearing in CBA mice and aimed to verify whether this hearing change is reversible by supplementation of zinc afterwards. We assessed hearing through an auditory brainstem response (ABR) with tone burst stimulation in 4, 8, 16, and 32 kHz and distortion product otoacoustic emissions in 5.6, 8, 11.3, and 16 kHz every week. The ABR threshold started to increase after 4 weeks on a zinc-deficient diet. The difference in the threshold between control and zinc-deficient animals became greater over time and plateaued at about 6 weeks. The ABR threshold differences between control and zinc-deficient mice were greater at higher frequencies. Four weeks of normal diet, following 8 weeks of a zinc-deficient diet, restored the ABR threshold to normal at all measured frequencies. Zinc-deficient mice did not show any distortion product otoacoustic emission threshold change at all frequencies. This finding suggests that a zinc-deficient diet increased the ABR threshold in CBA mice and a zinc-adequate diet restored the ABR threshold to normal.