Axonal GABA receptors are selectively present on normal and regenerated sensory fibers in rat peripheral nerve

A sucrose gap chamber was used to study the effect of gamma-aminobutyric acid (GABA) on normal and regenerating rat peripheral nerve fibers. Sciatic nerves and dorsal roots were depolarized by GABA and the GABAA receptor subtype agonist muscimol, but not by the GABAB receptor subtype agonist baclofen. Ventral root fibers were not affected by these agents, suggesting a selective presence of axonal GABA receptors on sensory fibers of mammalian peripheral nerves. Regenerating dorsal and ventral root fibers were studied 13 to 20 days following nerve crush. The regenerated dorsal root fibers were depolarized by GABA or muscimol, but the regenerated ventral root fibers were not. These results indicate that GABA receptors are selectively present on normal mammalian sensory axons, and are reestablished on regenerated sensory axons.