Fig. 3.

Low doses of TM activated a nonharmful, moderate UPR in the hippocampus. The freezing time in the trace fear conditioning test (a) and the number of learning trials in the Y-maze test (b) were recorded to analyze cognitive changes (n = 12). c Immunostaining was used to detect cleaved caspase-3 in the CA1 area of the hippocampus. Scale bar, 50 μm. d Quantification of cleaved caspase-3-positive cells in the CA1 area of the hippocampus. e The expression levels of cleaved caspase 3 and full-length caspase 3 in the hippocampus of rats were detected by Western blotting using specific antibodies. Each blot is representative of three experiments. f Quantification of cleaved caspase-3-positive cells in the CA1 area of the hippocampus. Each value was expressed relative to that in the naïve group, which was set to 100 (n = 6). g The TUNEL assay was performed to determine the extent of apoptosis in the CA1 area of the hippocampus. The arrows indicate cells showing an overlay of TUNEL and DAPI signals. Scale bar, 100 μm. h Quantitative analysis of TUNEL-positive cell content in different groups. *P < 0.05, **P < 0.01 vs. naïve group. The data are presented as the mean ± SEM. All experiments were repeated three times