Fig. 4

Hearing capacity and spiral ganglion neuron (SGN) density assessed 5 weeks after infection. Metformin therapy significantly improved click (p = 0.0015, a) and pure tone (4 kHz p = 0.0023, 8 kHz p = 0.0026, 16 kHz p = 0.0029, 32 kHz p = 0.0248, b) hearing thresholds in infected animals, without having an effect on hearing capacity in healthy animals (a). SGNs from the basal turn were protected from PM-induced cell death by metformin therapy (p = 0.0219, c)