Disorders in myelination in the twitcher mutant: Immunohistochemical and biochemical studies

The twitcher is an autosomal recessive mutant mouse characterized by absence of galactosylceramidase. The twitcher shows clinical and histological features similar to those of human Krabbe-type leukodystrophy. We here present the results of a neurochemical and immunohistochemical analysis of the twitcher. Electrophoretic analysis revealed that in the particulate fraction of the spinal cord, myelin basic proteins (MBP) and proteolipid protein were decreased, and in the sciatic nerve fibers, PO protein, X, Y and MBP were clearly decreased. 2′,3′-Cyclic nucleotide 3′-phosphodiesterase (CNPase) activities of the pallium cerebri, brain stem and spinal cord of the twitcher were about 20% less than those of the control. However, in the sciatic nerve, the activity was half that of the control. Immunohistochemical studies were carried out by means of antisera against MBP and CNPase. There were clear patches indicating both MBP- and CNPase-negative reactions in the white matter of the central nervous system from the twitcher. The reaction on the section of sciatic nerve fibers from the twitcher showed a positive reaction only in a very limited number of fibers with both MBP and CNPase antisera. A clear astrocytic hypertrophy was detected by the antiserum against glial fibrillary acidic protein (GFAP). Even in the grey matter of the cerebral cortex, strong GFAP-positive astrocytes were clearly observed.