Distribution of glutamic acid decarboxylase-immunoreactive structures in the barrel region of mouse somatosensory...

Neuronal structures in the barrel region of the mouse primary somatosensory cortex containing gamma-aminobutyric acid (GABA) were identified by an immunocytochemical method, using an antiserum to glutamic acid decarboxylase (GAD), the rate-limiting enzyme in the synthesis of GABA. GAD-positive cell bodies were found in all layers of the barrel cortex, but were more concentrated in the upper portion of layer II/III, and in layers IV and VI. Puncta, presumably axon terminals, were also distributed throughout the cortical layers; a high density of puncta occurs in layer IV, whereas a somewhat lower density characterizes layer VI. Based on the shapes of their somata and the distribution of their dendrites it was determined that all GAD-positive cell bodies were of the non-pyramidal type.