Identification of gamma-aminobutyric acid-like immunoreactive neurons in the rat cuneate nucleus.

Neurons in the cuneate nucleus of the rat were examined for gamma-aminobutyric acid-like immunoreactivity (GABA-LI) using antiserum raised against GABA-glutaraldehyde-keyhole limpet hemocyanin. GABA-LI neurons were analyzed for size, shape, and distribution and compared to Nissl-stained neurons. GABA-LI cell bodies were located at all rostral-caudal levels and were distributed randomly throughout the nucleus except at the level of the obex, where they were limited to the peripheral region of the cuneate nucleus. GABA-LI cell bodies had a significantly smaller mean cross-sectional area than the total cuneate neuronal population and comprised 21.5% of the total neuronal population as assessed with Nissl-staining. These results are consistent with the hypothesis that GABA is involved in processing somatosensory information in the rat dorsal column nuclei.