CEREBELLAR GLUTAMATE METABOLIZING ENZYMES IN SPINOCEREBELLAR ATAXIA TYPE-I

We measured the levels of three glutamate metabolizing enzymes, namely , glutamate dehydrogenase (GDH), aspartate aminotransferase (AAT), and glutamine synthetase (GS) in cerebellar and occipital cortices of nin e patients with dominantly-inherited olivopontocerebellar atrophy (OPC A; spinocerebellar ataxia type I). As compared with the controls, mean GDH activities in cerebellar cortex of the OPCA patients were normal whereas levels of AAT (-17%) and the glial enzyme GS (-27%) were signi ficantly reduced. No statistically significant changes were observed i n occipital cortex, a morphologically unaffected brain area. We sugges t that the decreased GS levels could reflect impaired capacity of astr ocytes to metabolize glutamate which might contribute to the degenerat ive processes in OPCA cerebellum.