Neurotransmitter chemistry in feline GM₁ gangliosidosis: A model for human ganglioside storage disease

Assays for synaptosomal high‐affinity uptake activity (glutamate, γ‐aminobutyric acid, norepinephrine), neurotransmitter synthesizing enzymes (choline acetyltransferase, glutamate decarboxylase, tyrosine hydroxylase), and endogenous neurotransmitters were performed in cats with advanced inherited GM₁ gangliosidosis. A significant reduction in uptake activity, ranging from 24 to 77% of control, was demonstrated in motor, occipital, and cerebellar brain regions. This reduction was unassociated with comparable alterations in neurotransmitter levels or synthesizing enzyme activity. We hypothesize that the defect of neurotransmitter inactivation is part of an overall abnormality of synaptic membrane function that could contribute to the neurological symptoms seen in the hereditary gangliosidoses.