Introduction

Little is known about the pathophysiological mechanisms of radicular pain. The substantia gelatinosa (SG) in the spinal cord dorsal horn receives primary afferent inputs, which predominantly convey nociceptive sensations. Nociceptive information is modified and integrated in the SG, suggesting that the SG may be a therapeutic target for treating radicular pain. Electrophysiological study using in vivo patch-clamp recording from SG neurons is a useful method to analyze functional properties in synaptic transmission. Transient receptor potential ankyrin 1 (TRPA1) has been widely identified in the central and peripheral nervous system such as peripheral nociceptor, dorsal root ganglion (DRG), and spinal cord dorsal horn, and is considered that they are involved in synaptic transmission of pain. However, it is still unknown about its functional role and mechanism of pain transmission in spinal cord dorsal horn. The purpose of this study is to investigate changes in excitatory synaptic transmission of SG neurons with TRPA1 antagonist and to clarify the potential role of TRPA1 in the rat spinal cord dorsal horn using in vivo patch-clamp analysis.