Figure 4. Activation of NFATc4 is a precursor to induction of apoptosis during the developmental critical period. A , Data of Western blot analysis of cellular fractions. Pretreatment with 30 mg/kg of the NFAT inhibitor peptide 11R-VIVIT (VIV) or CaN inhibitor FK506 attenuated the increase of nuclear NFATc4 in the cochlear nuclei of P7 mice 15 min after CX. Pretreatment with saline (sal) served as a vehicle control (23.19 ± 1.24%; t = 18.67; ** p < 0.01) and did not differ from untreated (–) animals (26.60 ± 1.28; t = 20.74; ** p < 0.01). Using paired t tests, means were compared with 0.0. B , Fluorescent photomicrographs of ApopTag-labeled AVCN neurons of P7 mice 24 h after CX. Images shown are AVCN on the side ipsilateral to CX. Pretreatment with 30 mg/kg (VIV 30) causes attenuated ApopTag labeling compared with untreated and saline-treated animals. Scale bar, 75 µm. C , Analysis of images (like those shown in B ) comparing the number of apoptotic neurons on the side ipsilateral versus contralateral to CX. Pretreatment with VIV 30 (6.45 ± 0.40; n = 5; t = 6.131;*** p < 0.001), VIV 20 (20 mg/kg; 10.80 ± 2.98; n = 7; t = 6.423; *** p < 0.001), or FK506 (4.31 ± 0.96; n = 4; t = 7.30; *** p < 0.001) significantly attenuated deafferentation-induced ApopTag labeling in P7 AVCN neurons 24 h after CX. Saline group does not significantly differ from untreated group. One-way ANOVA was used to compare means with untreated group.