C. Sasaki et al., Temporal profile of cytochrome c and caspase-3 immunoreactivities and TUNEL staining after permanent middle cerebral artery occlusion in rats, NEUROL RES, 22(2), 2000, pp. 223-228
Although apoptotic pathways play important roles in ischemic neuronal injur
y, exact mechanism of apoptotic enzyme cascade has not been fully studied.
Immunohistochemical stainings for cytochrome c and caspase-3, and histochem
ical staining for a terminal deoxynucleotidyl-transferase (TdT)-mediated dU
TP-biotin nick end-labeling method (TUNEL) were examined in a rat model of
permanent middle cerebral artery (MCA) occlusion. Cytochrome c was strongly
induced in neurons of the ischemic penumbra from 3 h after MCA occlusion,
and caspase-3 began to be induced in the same area from 3 h with a peak at
8 h. Neuronal cells in MCA area became TUNEL positive at delayed time, reac
hing a peak at 24 h. Thus, the peak of induction of cytochrome c preceded t
hat of caspase-3, and these two peaks were also precedence of the peak of D
NA-fragmentation. Western blot analysis showed cytosolic expression of cyto
chrome c from mitochondria. This study demonstrated 1. Rapid release of cyt
ochrome c from mitochondria to the cytosol, mainly in neurons of the cortex
at 3 h after ischemia. 2. Subsequent peaks of caspase-3 and TUNEL in this
order. These temporal profiles suggest a serial cascadic activation of apop
totic pathways in neuronal death after permanent MCA occlusion of rats.