Fig. 4.

Neonatal hypoxia–ischemia causes an elevation in proapoptosis Bax protein levels in the mitochondrial fraction but does not alter levels of antiapoptosis Bcl-2. A, Top, Immunoblot shows increased Bax protein levels in mitochondrial membrane fractions from the thalamus from homogenates obtained 3, 6, and 24 hr after neonatal hypoxia–ischemia compared with noninjured control samples (SC). Anti-Bax antibody recognizes the expected 21 kDa band corresponding to Bax protein. Bottom, The corresponding Ponceau-stained blot is shown. Each lanerepresents a pooled sample of thalamus from three animals at the indicated time point (i.e., sham control and 3, 6, or 24 hr after hypoxia–ischemia). B, In comparison Bcl-2 protein expression is not changed in mitochondrial membrane fractions from thalamus homogenates obtained 3, 6, and 24 hr after neonatal hypoxia–ischemia compared with noninjured control samples (SC). Anti-Bcl-2 antibody recognizes the expected 26 kDa band corresponding to Bcl-2 protein. Bottom, The corresponding Coomassie-stained gel is shown. C, Graph represents alteration in relative amounts of Bax and Bcl-2 protein in the mitochondrial membrane fraction in the thalamus over time after neonatal hypoxia–ischemia. By 3 hr, there is a significant shift in the Bax/Bcl-2 ratio favoring proapoptosis Bax. After correcting for protein-loading differences and comparing with control, results are shown as the mean ± SD of four to five pooled samples per time point (*p < 0.05 compared with control).