Establishment of Imaging Mass Spectrometry for Biological Tissues and Its Application on the Proteome Analysis of Microwave Radiated Rat Hippocampus

Imaging mass spectrometry based on matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) for biological tissues was established. The key experimental factors were optimized as follows: 20 mg ml−1 of sinapic acid as matrix, ACN:H2O (1:1, v/v) as matrix solvent; MALDI-TOF-MS was operated at positive linear scan mode, 30%–50% of laser power range, 200 laser shots per scan, and 200 μm as the laser moving step. This method was used for the proteome analysis of SD-rat brain hippocampus after microwave radiation. 5902 spectra and 320 MS images per slice for normal group were acquired; 5993 spectra and 346 MS images per slice for microwave radiation group were acquired. Software was developed to calculate the Hits values, which reflected the component distribution and abundance. By statistic analysis of normal species and radiation group, a total of 199 differentiate molecules were found, out of which 194 molecules were up regulated. These molecules may be important for investigating the injury mechanism of hippocampus microwave radiation.