Dysmyelinogenesis in animal model of GM 1 gangliosidosis

Abstract

Magnetic resonance imaging (MRI), pathologic examinations, and biochemical analyses were performed on 2 different canine mutants with GM 1 gangliosidosis (i.e., English Springer Spaniel and Portuguese Water Dog) and on age- and sex-matched controls. Serial MRI studies were also performed on a child with infantile-onset GM 1 gangliosidosis. The affected dogs had abnormalities on MRI, including a relative increase in gray matter and an abnormal signal intensity of cerebral and cerebellar white matter observed on T 2-weighted MRI. White matter changes on MRI were similar to white matter abnormalities observed in a 15-month-old boy with GM 1 gangliosidosis. The weight ratio of white to gray matter from the frontal lobe was markedly reduced. Microscopic examination revealed characteristic ballooned neurons which stained lightly with Luxol-fast blue. The central cerebral and cerebellar folia white matter exhibited pallor and gliosis, while the corpus callosum and fornix stained normally with Luxol-fast blue. Axons appeared intact on Bodian staining. Ultrastructural studies revealed fewer myelinated axons in affected puppies. Total gangliosides in gray matter were elevated. Thin-layer chromatography demonstrated GM 1 ganglioside as the predominant ganglioside. The amount of cerebrosides and sulfatides was reduced in the gray and white matter when compared to controls but the ratio in gray and white matter remained unchanged. Immunostaining of neutral glycolipids disclosed increased amounts of stage-specific embryonic antigen-1 glycolipid in gray matter. These findings suggest that canine models for GM 1 gangliosidosis are associated with abnormal myelin development which may be similar to the human disease.