Figure 5. FGF22 depletion reduces ribbon synapse number in vivo. AAV-shFGF22 and AAV-FGF22 were administrated to mouse cochlea to deplete or overexpress FGF22 in hair cells, respectively. Co-administration of AAV-shMEF2D with AAV-shFGF22 was also performed to assess the regulatory relationship between FGF22 and MEF2D in hair cells and ribbon synapses. Similarly, co-administration of AAV-MEF2D with AAV-FGF22 was performed, also to assess the regulatory relationship between FGF22 and MEF2D in hair cells and ribbon synapses. (A, B) TUNEL staining was performed on cochlea, showing by representative images (A), and by quantification (B). (C, D) The ribbon synapses were determined by co-staining for CtBP2 (in green) and GluR2&3 (in red). Cochlear ribbon synapse number was assessed, shown by representative images (C), and by quantification (D). *p<0.05. NS: non-significant. N=5. Scale bar is 20μm.