Neuronal, but not microglial, accumulation of extravasated serum proteins after intracerebral hemolysate exposure is accompanied by cytochrome c release and DNA fragmentation

Vasogenic edema after oxidative injury has been accompanied by intracellula r accumulation of serum proteins and nuclear damage. This study sought to d etermine whether serum protein accumulation, along with other markers of br ain injury, was present after exposure to intracerebral hemolysate, an oxid ant model of intracerebral hemorrhage (ICH). Saline (n = 24) or hemolysate (n = 30) was injected into the caudate-putamen of adult Sprague-Dawley rats . Compared with saline, hemolysate deposition was associated with intracell ular accumulation of serum proteins as evidenced by Evans blue uptake in ne urons and microglia at 4 and 24 hours. Intracellular Evans blue colocalized with DNA fragmentation detected by nick end-labeling and whose presence wa s confirmed by gel electrophoresis. Immunoblots of cytosolic fractions conf irmed cytochrome c release. Immunostaining established colocalization of cy tosolic cytochrome c and intracellular Evans blue at 4 hours. At 24 hours, cytosolic cytochrome c was evident in astrocytes surrounding Evans blue-pos itive cells. Immunoblot analysis and immunostaining revealed HSP70 inductio n at 24 hours in regions adjacent to intracellular serum accumulation. Neur onal accumulation of extravasated serum proteins in this model of ICH was a ssociated with cytochrome c release, DNA fragmentation, and cell death. Str ess protein induction in adjacent regions suggested that vasogenic edema mi ght have exacerbated cellular dysfunction and cell death after ICH.