Glutamate decarboxylase immunoreactivity and gamma-3H aminobutyric acid accumulation within the same neurons in dissociated cell cultures of cerebral cortex

In order to evaluate the reliability of high affinity 3HGABA accumulation as a marker for GABAergic neurons, murine cerebral cortical neurons were studied in dissociated cell culture. Cultures which had been incubated in 3HGABA were stained immunohistochemically for the GABA-synthesizing enzyme, glutamate decarboxylase, fixed with paraformaldehyde, and subsequently processed for radioautography. In mature cultures, there was an 84 to 94% correlation between the presence of the enzyme and 3HGABA uptake within the same cortical neurons. These data provide direct evidence that those neurons which synthesize GABA are the same neurons which are labeled by high affinity 3HGABA uptake.