Assessment of Synaptic Plasticity via Long-Term Potentiation in Young Mice on the Day after Acoustic Trauma: Implications for Tinnitus.

OBJECTIVE

This experimental study evaluated the pathophysiological association of long-term potentiation (LTP)-mediated synaptic plasticity in tinnitus in 30 BALB/c mice.

MATERIALS AND

METHODS

Baseline hearing levels and tinnitus perception were examined with startle reflex time and gap detection time measurements using an acoustic stimulus of a 6-kHz pure tone at 90 dB sound pressure level (SPL) on post-natal day 16. The acoustic trauma group was exposed to 6-kHz pure tone at 120 dB SPL on post-natal day 16. On post-natal day 17, the acoustic trauma group underwent re-measurements of hearing levels and tinnitus perception using an acoustic stimulus of 6-kHz pure tone at 100 dB SPL. Fifteen tinnitus-induced and fifteen control subjects were sacrificed on post-natal day 17, and LTP in the dorsal cochlear nuclei of each animal was examined.

RESULTS

With respect to gap detection time, there were no statistically significant between-group differences; however, there was a statistically significant difference between the pre- and post-trauma period in the acoustic trauma group. Moreover, LTP was significantly higher in the acoustic trauma group than in the control group.

CONCLUSION

The results suggest that LTP underlies tinnitus pathogenesis.