GA inhibits apoptotic cell death of neurons and oligodendrocytes after SCI
To determine the neuroprotective effect of GA after SCI, we performed Cresyl violet staining and compared the number of motor neurons in ventral horn 1d after injury. As shown in Fig. 7A, a massive loss of VMNs was observed in the lesion area after injury, as reported (Yune et al., 2008), while GA treatment significantly inhibited VMN loss in both rostral and caudal to the lesion epicenter when compared with that of the vehicle-treated group (Fig. 7A and B). Next, TUNEL staining showed that TUNEL-positive cells were observed mostly near and within the lesion area in the GM at 1 d (Fig. 7C) and in the WM at 5 d (Fig. 7D) mostly outside of the lesion area extending the entire length of the section (20 mm). Furthermore, GA significantly decreased the number of TUNEL-positive neurons in the GM at 1 d (Fig. 7C and E) and oligodendrocytes in the WM at 5 d (Fig. 7D and E) when compared with the vehicle control. Immunostaining with cleaved caspase-3 antibody also revealed that GA treatment significantly reduced the number of activated caspase-3-positive cells in the WM at 5 d after injury compared to that of the vehicle control (Fig. 7F and H). Furthermore, double immunofluorescence staining showed that the cleaved caspase-3-positive cells in the WM at 5 d after SCI were CC1-positive oligodendrocytes (Fig. 7G). In addition, GA treatment significantly decreased the levels of the cleaved forms of caspase-3 at 5 d after injury compared to that of the vehicle control (Fig. 7I).