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 [3H]GABA accumulation as a marker for GABAergic neurons, murine cerebral cortical neurons were studied in dissociated cell culture. Cultures which had been incubated in [3H]GABA 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 [3H]GABA 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 [3H]GABA uptake.