Fig. 5

Vagus nerve stimulation decreases neuronal death after 12 min CA and resuscitation. For nissl, TUNEL, and NeuN staining, we used three serial coronal sections from each groups (n = 3, sham, control and tVNS). Nissl staining with red arrows indicating damaged neurons in the CA1 of hippocampus and cortex region in brain. The average number of damaged neurons in the CA1 regions of the hippocampus and cortex were significantly increased in CA rats as compared to sham rats (P < 0.0001). tVNS administration after CA significantly reduced the number of damaged neurons in CA1 regions of the hippocampus (P < 0.001) and cortex (P < 0.01) as compared to control (A). TUNEL staining shows the apoptotic cells in the CA1 of hippocampus and cortex region in brain. The average number of apoptotic cells in the CA1 regions of the hippocampus were significantly increased in CA rats as compared to sham rats (P < 0.001). VNS administration after CA significantly reduced the number of apoptotic cells in CA1 regions of the hippocampus (P < 0.01) and cortex (P < 0.001) as compared to control (B). NeuN staining shows the functional state of neurons. The average number of neurons in the cortex regions of the brain were significantly reduced in CA rats as compared to sham rats (P < 0.05) however, no significant differences were observed between sham and VNS groups (C). Scale bar 50μm.  Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001. VNS =  vagus nerve stimulation