Fig. 4.

Evidence for cell death in Gaa^−/− cervical spinal cord. Upregulation of mRNA expression of genes for cytotoxicity, necrosis, and apoptosis occurred in Gaa^−/− tissues (A). Analysis of the top 100 upregulated KEGG signaling pathways (FDR q value <0.05) revealed enriched signaling pathways related to cell death (B). Enriched signaling pathway data are expressed as the negative log₁₀ of the P value. Histological examination showed terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells throughout cervical spinal tissue from Gaa^−/− but not WT tissues at 6–8 mo (C) and 12–15 mo (D), indicating on-going neuronal cell loss. In C and D, i indicates the dorsal horn region, and ii indicates the ventral horn region. Calibration bars indicated 200 μM (lower-power images) and 20 μM (higher-power images).