Figure 1.
Axonal morphological changes demonstrated by in vivo tracing in the different brain areas after transient cerebral ischemia/reperfusion.
Right panels were high magnification views of the areas in left panels in A–E (single arrow), respectively. Typical swollen axons or varicosities (arrowheads) could be seen in the primary sensory cortex (Psc) (A), primary motor cortex (Pmc) (B), hippocampus (Hi) (C) and caudoputamen (Cpu) (D) of the ischemic hemisphere after transient cerebral ischemia/reperfusion. No obvious axonal changes were noticed in the primary sensory cortex from the sham group (E). Scale bars: 20 µm for left panels and 5 µm for right panels in A–E.
Figure 2.
Transient cerebral ischemia/reperfusion induces early and chronic axonal changes.
Representative axonal changes (swellings of axons and varicosities) can be seen at 6 h, 24 h, 1 w, 2 w, 3 w and 4 w after transient cerebral ischemia/reperfusion in different brain regions, including the ischemic primary sensory cortex (Psc) (A), primary motor cortex (Pmc) (B), hippocampus (Hi) (C), caudoputamen (Cpu) (D) and peri-lesional cortex (E). Arrowheads in each figure mark the swollen axons or varicosities. Scale bars: 5 µm for A–E.
Figure 3.
Semi-quantitative score of the degree of axonal changes in ischemic brain regions of transient cerebral ischemia/reperfusion and control rats from axonal tracing evaluation.
The degree of swollen axons and varicosities was particularly obvious at 2 w after transient cerebral ischemia/reperfusion. Such axonal damages could extend to 4 w as compared to the corresponding contra-lateral brain regions in sham groups, although appeared to self-recover temporarily at 1 w. The score at each time point represents 13–19 values (Mean±SD) obtained from 3–4 rats in each subgroup. The asterisk indicates a highly significant difference (P<0.01) between the transient cerebral ischemia/reperfusion subgroup and the corresponding sham subgroup.
Table 1.
Semi-quantitative analysis of the degree of axonal changes in different brain regions in transient cerebral ischemia/reperfusion and control rats from axonal tracing evaluation.
Figure 4.
Tracing and immunohistochemical double staining show the tracer-labeled neurons and the expression of hyperphosphorylated Tau induced by transient cerebral ischemia/reperfusion.
B, D and F are the magnification of an area in A, C and E, respectively. Some staining for AT8 (brown color) was found in the ischemic cortex (A) and AT8 labeled neuronal bodies could be noticed (B, arrowheads). The arrows in B indicate the tracer-labeled neurons (dark blue color). Strong staining for Tau-5 (brown color) was found in the ischemic cortex (C) and the extensive Tau-5 labeled neurons (D, arrows) and swollen axons (D, arrowheads) were noticed. Inserted figure in C showed the magnification of an area (arrowhead), demonstrating the tracer-labeled neurons (dark blue color). Only very weak staining could be observed for P-tau (E) and tracer-labeled neurons presented the morphological changes as cell shrinkage occurred. Scale bars: 10 µm for B, D, and F, 100 µm for A and C, 200 µm for E.
Figure 5.
Western blot testing shows the expression of hyperphosphorylated Tau induced by transient cerebral ischemia/reperfusion.
The level of Tau protein increased in the ischemic cortex of the transient cerebral ischemia/reperfusion subgroup compared to the corresponding region in the sham group (A through D). The levels of AT8 and Tau-5 increased obviously at 1 w after transient cerebral ischemia/reperfusion (B and D), whereas a similar increase was detected in the level of P-tau only at 6 h after transient cerebral ischemia/reperfusion (C). The asterisk indicates a significant difference (P<0.05) between this subgroup and the other five subgroup.