Innervated Properties of Acupuncture Points LI 4 and LR 3 in the Rat: Neural Pathway Tracing with Cholera Toxin Subunit B

Abstract Objective: Increasing evidence from acupuncture research suggests that the nervous system corresponds closely with classical acupuncture points. The aim of this research was to provide neuroanatomical evidence for revealing the innervated properties of different acupuncture points through comparing the sensory and motor pathways associated with Hegu (LI 4) and Taichong (LR 3) in rat extremities. Materials and Methods: Cholera toxin subunit B (CTB) was injected into LI 4 and LR 3 in different rats, and CTB neural labeling was examined using fluorescent immunohistochemistry and observed under fluorescent microscopy in the corresponding areas from the peripheral nervous system to the central nervous system, including the dorsal root ganglia (DRG), spinal cord, and brainstem. Results: When LI 4 was injected with CTB, CTB-labeled sensory neurons ranged from C–5 to T–1 DRG, and their transganglionic axons terminated in the C–5 to C–8 spinal dorsal horn as far as the cuneate nucleus, while labeled motor...