In situ chemical analyses from frozen tissue sections by Fourier transform infrared microspectroscopy. Examination of white matter exposed to extravasated blood in the rat brain.

摘要

Fourier transform infrared (FT-IR) microspectroscopy is a powerful technique for obtaining chemical information from tissue sections. Infrared spectra can be collected from individual spots or from several spots along a grid pattern. In the latter example, absorbing bands are interpolated between spectra to generate maps that represent the relative concentrations of chemical groups. In this study, blood was injected into the subcortical white matter of the rat, and the spatial distribution of chemical changes was identified at 2 and 6 days after injection. The absorbances for CH2, H-C = C, C = O, P = O, and HO-C-H were lower at the lesion site compared with the neighboring tissue, which suggests a mechanism of lipid peroxidation. The absorbances for N-H stretch and amide II were greater at the lesion site compared with the surrounding tissue, and the amide II peak was shifted toward lower wave numbers in the affected area. These changes are probably due to the infiltration of blood products, the aggregation of myelin proteins, and/or gliosis in the lesioned tissue. The rate of absorbance change per distance displayed a trend to be more abrupt at 2 days compared with 6 days after injection. We suggest that FT-IR microspectroscopy can be applied to a variety of disease states.