Figure 8.

Susceptibility to apoptosis in newly generated OSNs is enhanced 7–14 after injury and unilateral nostril occlusion. A, Mice in two experimental groups received unilateral nostril occlusions (n.o.) at different times after methimazole-induced injury. Top, Sensory deprivation 0–7 d, n.o. (d0–7); bottom, sensory deprivation 7–14, n.o. (d7–14). Mice in the n.o. d 0–7 group received both methimazole administration and unilateral nostril occlusion on day 0; however, the nostril occlusion was removed on day 7 (reopen). Mice in the n.o. d 7–14 group received methimazole administration on day 0 and unilateral nostril occlusion on day 7. Mice in both groups were perfused with fixative (fixed) on day 14 after the methimazole-induced injury. B, Photomicrographs of representative coronal sections of the olfactory nasal septum in the two groups. Higher magnification views of the OE captured from the area depicted by the square are illustrated in the bottom photomicrographs. Scale bars, 100 μm (lower magnification) and 20 μm (higher magnification). C–E, Thickness of the OE (C), number of OSNs (D), and number of supporting cells (E) in both the n.o. d 0–7 and n.o. d 7–14 groups. F, Representative coronal sections of the olfactory nasal septum stained with anti-OMP antibody in both the n.o. d 0–7 and n.o. d 7–14 groups. Scale bar, 20 μm. G, Number of OMP-positive cells through the nasal septum in both the n.o. d 0–7 and n.o. d 7–14 groups. The number of OMP-positive cells in the n.o. d 0–7 group does not differ between the open and the occluded sides, whereas for the n.o. d 7–14 group, the number of OMP-positive cells on the occluded side is significantly bottom than that on the open side (***p < 0.001; n.s., not significant; Mann–Whitney test). H, Photomicrographs of representative coronal sections from the olfactory nasal septum stained with anti-caspase-3 antibody in both the n.o. d 0–7 and n.o. d 7–14 groups. Arrowheads show caspase-3-positive cells. Scale bar, 20 μm. I, Number of caspase-3-positive cells in both the n.o. d 0–7 and n.o. d 7–14 groups. The number of caspase-3-positive cells in the open and closed sides of the n.o. d 0–7 group does not change (n.s., not significant; Mann–Whitney test), whereas the number of caspase-3-positive cells on the occluded side is significantly higher than that on the open side in the n.o. d 7–14 group (***p < 0.001; Mann–Whitney test). J, Two experimental groups: top, caspase inhibitor administration; bottom, DMSO administration. Both groups of mice received unilateral nostril occlusion 7–14 d after methimazole-induced injury. Mice were administered a caspase inhibitor or DMSO (control) on days 7, 9, 11, and 13 after the injury. On day 14 after injury, mice in both groups were perfused with fixative (fixed) for analysis. K, Photomicrographs of representative coronal sections from the olfactory nasal septum are shown for both groups (caspase inhibitor administration and DMSO administration). Higher magnification views of the OE captured from the areas depicted by the squares are illustrated in bottom images. Scale bars, 100 μm at lower magnification, 20 μm at higher magnification. L–N, Thickness of OE (L), number of OSNs (M), and number of supporting cells (N) in groups administered a caspase inhibitor or DMSO. The thickness of the OE and number of OSNs on the occluded side are significantly decreased compared with those on the open side in the group administered DMSO (***p < 0.001; Mann–Whitney test), whereas no histological differences were observed between the two sides in the group administered the caspase inhibitor (n.s., not significant; Mann–Whitney test).