Fig. 3.  Caspase-3 activation in the brain and spinal cord of postnatal day (P) P7 rat pups. Representative photomicrographs illustrate examples of cleaved caspase-3 immunocytochemical labeling in the somatosensory region of the cortex and spinal cord. Minimal labeling was found in brain (A , B ) and spinal cord (E , F ) sections from groups treated with spinal normal saline (A , E ), spinal bupivacaine (B , F ), or isoflurane 1 h (not shown), while markedly increased label was seen in both the brain (C ) and spinal cord (G ) in rats exposed to 6 h of 1% isoflurane. Summary data on cleaved caspase-3 positive cells are shown for brain (D ) and spinal cord (H ). White arrows  in panels C  and G  highlight the presence of cleaved caspase-3 positive cells in the cortex and spinal cord, respectively. Sample size for all spinal cord labeling groups was 7 animals with the exception of isoflurane 1 h (n = 6) (total, n = 41). Sample sizes for brain labeling varied by group: n = 12 for low-dose spinal bupivacaine (performed awake), n = 10 for spinal normal saline, n = 6 for isoflurane 1 h, n = 7 for isoflurane 6 h, n = 8 for no treatment, n = 7 for low dose spinal bupivacaine performed under brief (less than 2 min) isoflurane general anesthesia (total, n = 50). Data are presented as mean ± SD, *P < 0.05 compared with other cohorts. Scale bar = 100 μm. Bupi = bupivacaine; Iso = isoflurane; NT = no treatment.