Objective: The spinal segmental distribution of neural innervations related to "Guanyuan"(CV 4) in rats has been investigated by horseradish peroxidase conjugated cholera toxin B subunit(CB-HRP) tracing technique.Methods: Twelve SD female rats were divided randomly into electroacupuncture group(EA) and control group(C).CB-HRP solution(0.03%(20 μL)) was injected into "Guanyuan" acupoint of the rats. The HRP labeled neurons were observed morphologically and counted in the related spinal dorsal root ganglia(DRG).Results: The sensory nerve afferents of "Guanyuan" acupoint mainly projected to the neurons of T_(11) to L_3 DRG.The labeled neurons were observed to be large

medium and small sized cells

of which the small size was in The majority.The number of labeled neurons in EA group was increased significantly compared with control group((P<0.05)).The nerve fibers projected to L_2 were activated by the EA treatment and the number of HRP labeled cells in L_2 DRG was increased significantly.Conclusion: EA at "Guanyuan" acupoint may affect the local innervation activity

resulting in the projection of the local primary sensory afferents focusing on L_2 DRG.So this study provides a new morphological evidence for transduction of acupuncture signals.