Assessment of post-mortem-induced changes to the mouse brain proteome

This study was designed to assess the influence of high-energy head-focused microwave irradiation and the post-mortem interval on measurements of the mouse brain proteome. Difference gel electrophoresis was used to compare mouse brain protein levels in animals killed by decapitation, where the tissue was held at 25°C for selected time intervals post-mortem, and by high-energy head-focused microwave irradiation followed by immediate resection. Microwave-mediated killing was used because it comprehensively snap-inactivates enzymes while largely retaining brain cytoarchitecture. Of the 912 protein spots common to at least eight of 10 gels analyzed, 35 (3.8%) showed significant differences in levels (t-test; p < 0.05) depending on whether animals were killed by microwave irradiation or decapitation. When animals were killed by decapitation, 43 protein spots (4.7%) showed changes in levels over the post-mortem interval (anova; p < 0.05). The vast majority of the near 1000 proteins evident on a 2D gel were stable for up to 4 h. These data have important implications for studies of proteins in the brain, whether based on analysis of tissue derived from animal models or from humans.