[Review on application of neural tracing technique to experimental research of acupuncture]

To collect literatures on the application of neural tracing technique in experimental acupuncture research, and summarize its application status in acupoints, meridians and Zang-fu organs.We collected papers published from databases of CNKI (1979-2017), Wan-Fang (1990-2017), VIP (1989-2017) and PubMed(1997-2017)by using keywords of "neural tracing technique" "neuroanatomic tracing" "neural tracers" and "acupuncture" "electroacupuncture" "auricular acupuncture" "eye acupuncture" "meridians" "acupuncture points" "acupoint injection", and made a summary about the current state of application of neural tracing technique in the fields of acupoint, meridian and Zang-fu organs (viscera).A total of 94 articles were collected, the most commonly used neural tracers were horseradish peroxidase and cholera toxin subunit B. The experimental animals used were rat, rabbit, cat, monkey, etc., and injection site was acupoint. After the injection of neural tracers, the survival time of animals was range from 1 day to 12 weeks, and the labelled tissues included neurons and nerve fibers of the sensory, motor, and autonomic systems. The outcomes of neural labeling mainly revealed the segmental pattern, neuroanatomical connection (neural pathways/circuits) and chemical features (shown by immunohistochemical staining) of neurons and nerve fibers innervating both the acupoints and visceral organs, suggesting their involvement in the effect of acupuncture and moxibustion treatment.This application of neural tracing technology help us understand the under-lying mechanisms of acupuncture and moxibustion interventions from different perspectives of neural pathways/circuits and related chemical properties, which also lays a greater role for this technology in future experimental acupuncture research.