Astrocytosis in wobbler mouse spinal cord involves a population of astrocytes which is glutamine synthetase-negative

Mice affected by the wobbler mutation are characterized by a muscular atrophy associated with motoneuron degeneration. As soon as the first clinical signs of the disease appear, reactive astrocytes, strongly glial fibrillary acidic protein (GFAP)-positive, are observed in the spinal cord grey matter. They become prevalent at all levels with disease progression. Immunostaining of glutamine synthetase (GS) shows that these reactive astrocytes are never GS-positive. The activity and protein amounts of GS remain normal in wobbler spinal cord although astrocytosis develops. Thus, gliosis in the wobbler mouse seems to involve a subpopulation of astrocytes, which is strongly GFAP-positive but GS-negative.