Intermittent hypercapnic hypoxia induced protein changes in the piglet hippocampus identified by MALDI-TOF-MS

Intermittent hypercapnic hypoxia (IHH) induces protein changes in the brainstem, but its effects on the hippocampus have not yet been studied. Using a proteomics-based approach, we tested the hypothesis that IHH up-regulates apoptotic promoters and down-regulates apoptotic inhibitors in the developing hippocampus. Male piglets aged 13-14 days were assigned to control (n = 6) or IHH (n = 5) groups. Using two-dimensional polyacrylamide gel electrophoresis, matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), a total of 26 protein spots were differentially expressed in IHH compared to control group. Thirteen of these (6 up-regulated, 7 down-regulated) were identified including 14-3-3θ/τ (increased), glial fibrillary acidic protein (increased) and a-internexin (decreased). Further analysis with western blot validated these proteins and immunohistochemistry showed specific regional changes in the subiculum, stratum radiatum and CA1 of the hippocampus. Most proteins identified were involved in promoting cell survival under apoptotic conditions. These findings improve our understanding of the cellular processes that occur in the hippocampus during IHH exposure, and have important implications in clinical settings where IHH is experienced, for example, during prone sleeping or with obstructive sleep apnea in an infant.