NEUROPATHOLOGY OF TWITCHER MICE - EXAMINATION BY HISTOCHEMISTRY, IMMUNOHISTOCHEMISTRY, LECTIN HISTOCHEMISTRY AND FOURIER-TRANSFORM INFRAREDMICROSPECTROSCOPY

The twitcher mouse is an authentic animal model of globoid cell leukod ystrophy, which is a genetic disease that affects the lysosomal enzyme galactocerebroside beta-galactosidase. This enzyme deficiency causes one of its substrates, galactosylsphingosine (psychosine), to accumula te in myelin-forming cells, which eventually results in their death. I n the central nervous system, the death of oligodendrocytes is thought to cause a series of secondary pathological changes. In this study, s everal techniques were utilized to examine the neuropathology of two d ifferent brain regions in the twitcher mouse-the hindbrain and the cer ebrum. Neuropathological changes were as follows: (1) demyelination wa s detected in the hindbrain but not in the cerebrum, (2) a high densit y of periodic acid-Schiff-positive cells were detected in the hindbrai n and to a lesser extent in the cerebrum, (3) astrocyte gliosis was pr onounced in both the hindbrain and cerebrum, and (4) macrophages were abundant in both the hindbrain and the cerebrum. We found that Periodi c acid-Schiff-positive cells, astrocyte gliosis and macrophage infiltr ation were present in white and gray matter regions of the cerebrum, w hile they were generally absent from the granule and molecular layers of the cerebellum. In addition to these studies, we utilized the techn ique of Fourier transform infrared (FT-IR) microspectroscopy to identi fy the in situ distribution of psychosine in the brains of twitcher mi ce. Evidence was obtained that indicates a large accumulation of psych osine in the hindbrain, and to a lesser extent in the white matter of the cerebrum in the twitcher mouse, but not the normal mouse. There wa s no evidence for the accumulation of psychosine in the molecular laye r of the cerebellum from the twitcher or normal mouse. Our conclusions are as follows: (1) pathology is more advanced in the hindbrain compa red to the cerebrum, which is likely due to the hindbrain becoming mye linated prior to the cerebrum, (2) demyelination is not necessary for the development of secondary pathological changes, (3) pathology is no t limited to white matter in the cerebrum, (4) pathology is not presen t in all brain regions, i.e. the granule and molecular layers of the c erebellum are devoid of pathological changes, and (5) psychosine accum ulates in both the cerebrum and hindbrain, but not in the molecular la yer of the cerebellum in the twitcher mouse. This study demonstrates t hat FT-IR microspectroscopy can be used to correlate chemical changes to histopathological changes in brains from twitcher mice, which sugge sts that FT-IR microspectroscopy may be a useful tool for studies exam ining other brain diseases.