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. Author manuscript; available in PMC: 2014 Dec 15.
Published in final edited form as: Cell Rep. 2014 Sep 15;8(6):1731–1740. doi: 10.1016/j.celrep.2014.08.030

Figure 4. Toluidine Blue Staining and Transmission Electron Microscopy Visualization of Hippocampal Protection by orally administered (−)-P7C3-S243 after Blast-Injury.

Figure 4

Daily oral administration of the highly active enantiomer (−)-P7C3-S243 for 14 days, starting 24 hours after injury, dose-dependently preserved CA1 morphology, as well as myelin and mitochondrial structures in the hippocampus after blast-injury. Two-weeks after either sham or blast-injury, animals were perfused and processed for ultrastructural pathology. Toluidine blue-stained semithin sections (left panel) of sham-injured mice treated with vehicle or (−)-P7C3-S243 showed normal CA1 histology, with densely packed neurons in the stratum pyramidale (1) and profuse dendritic profiles in the stratus radiatum (2; black arrows). Blast-injured animals treated with vehicle showed accumulation of chromatolytic and pyknotic neurons (white arrow) throughout the stratum pyramidale, as well as fewer dendrites in the stratum radiatum. There is no protection in CA1 morphology at the lowest concentration of blast-injured animals treated with 0.3 mg/kg/d of (−)-P7C3-S243. However, treatment with 3mg/kg/day (−)-P7C3-S243 lowered the abundance of chromatolytic and pyknotic neurons, and resulted in a more densely packed stratum pyramidale. At the highest concentration (30mg/kg/day) of (−)-P7C3-S243, there was complete preservation of CA1 morphology after blast-mediated TBI. Transmission electron micrographs (TEM; right panel) of immediately adjacent ultrathin sections showed normal myelin and axonal mitochondrial structures in the stratum radiatum of sham-injury mice treated with vehicle or (−)-P7C3-S243. Blastinjured mice treated with vehicle or 0.3mg/kg/day of (−)-P7C3-S243 showed degeneration of myelin sheath (red arrows), along with abnormal outer membrane and internal cristae structures within neuronal mitochondria (blue arrows). At 3 and 30mg/kg/day doses, however, both myelin and neuronal mitochondria were preserved. Pictures shown are representative of 4 animals per condition. Scale bars: Toluidine blue: 50uM; TEM: 500nm. See also Figure S4.