Figure 4.

Co-labeling of VGLUT1-ir and VGLUT2-ir with terminal endings of SP5 and auditory nerve in the CN (n=2). (A, B) Percentages of SP5 terminals (A) and auditory nerve terminals (ANF, (B)) co-labeling with VGLUT1-ir (black columns) and VGLUT2-ir (white columns). (A) About 50% of Sp5 mossy fibers (m) and 12% of small Sp5 boutons (b) colabeled with VGLUT2. Significantly fewer mossy fibers and boutons colabeled with VGLUT1 (paired t-test, P < 0.05); 23.6% ± 1% of total Sp5 terminal endings (mb, both mossy fibers and boutons) colabeled with VGLUT2, which is significantly greater than the endings colabeled with VGLUT1 (2% ± 0.1%; paired t-test, P < 0.05). (B) In contrast, many labeled ANF terminals colocalized with VGLUT1 in the VCNm (79.5% ± 7% endbulb-like terminals (e), 43.0% ± 3% bouton terminals (b)) as well as in the DCN3 (26.0% ± 5%). Neither ANF endbulb-like terminals nor small boutons were colocalized with VGLUT2. Error bars represent SEM. Asterisks indicate significant differences (see text). (C) High-magnification confocal images (×63) showing colocalization of anterogradely labeled Sp5 terminal endings with VGLUT2-ir in the small cell cap (SCC) of the CN. Green, VGLUT-ir; red, Sp5 labeling; yellow, double-labeled terminals. Images were obtained from Z projections of stacks of serial 1-μm confocal images. Insets show a single 1-μm confocal image. Mossy fibers are labeled with BDA from Sp5 and VGLUT2 in the shell. Colocalization of Sp5 MFs with VGLUT2-ir is indicated by arrowhead in C3. (Abbreviations: m – mossy fibers; b -boutons; mb - total (mossy fibers and boutons); e - endbulb-like terminals). (Adapted with permission from Zhou et al., 2007)