Peripheral glutamate release in the hindpaw following low and high intensity sciatic stimulation

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Abstract

The present study demonstrates that following A and/or C fiber stimulation of the sciatic nerve, glutamate levels increase significantly in the hindpaw extracellular space. In hindpaw dialysate, electrical stimulation (5 min) of the sciatic nerve at 2×, 20×, 50× or 200× threshold current required to produce a muscle twitch resulted in peak glutamate increases of 120.8 ± 9%, 134.3 ± 5%, 153.9 ± 10% and 150.5 ± 5% of basal levels, respectively. Application of 1% capsaicin to the sciatic nerve (10 min) to selectively activate C fibers resulted in a peak glutamate increase of 130.8 ± 8% of basal levels. Aspartate levels did not change significantly in either paradigm. These data indicate that low and high intensity stimulation can result in peripheral release of glutamate, providing a major source of ligand for the glutamate receptors localized on peripheral primary afferents.

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