Fig. 8

Endogenous EPO produced by astrocytes under hypothermic conditions reduced the number of TdT-mediated dUTP nick-end labeling (TUNEL)-positive apoptotic neurons. Neurons were exposed to OGD for 2 h and reperfused in astrocyte-conditioned medium (ACM) from OGD-hypothermic astrocytes with either control or EPO-neutralizing IgG. Apoptotic neurons were identified by TUNEL staining. Nuclei were stained with 4,6-diamidino-2-phenylindole (DAPI; blue). a Representative immunofluorescence images of TUNEL staining after 24 h of reperfusion. Bar, 50 μm. b Quantification of neuron apoptosis after OGD-associated injury. Blockade of EPO signaling using an EPO-neutralizing antibody promoted neuron apoptosis with 24 h of reperfusion. The addition of EPO to non-conditioned culture medium at the same concentration as in hypothermic ACM (18 pg/mL) did not change the population of TUNEL-positive cells. Data are the mean ± SEM (n=6 fields in each group). ^*P < 0.05 compared with the hypothermic ACM/control IgG group