SHE Chen，W ANG Jia, HA Lijuan，CUI Jingjing，XU Dongsheng，BAI Wanzhu 

(1 Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China; 2 Changchun University of Chinese Medicine, Changchun 130117) 

Abstract: Objective: To analysis the research progress and characteristics of neural tracing technique for the  morphological  study  of  acupuncture,  and  reveal  the  effect  of  this  technology,  also  provide neuroanatomical evidences for the optimization of morphological research plans. Methods: Five databases were searched from their inception: CNKI (1979-2017), Wan-Fang Data (1990-2017), VIP Data (1990-2017)  and  PUBMED  (1989-2017).  Studies related  to  the  neural  tracing  technique  for  the  acupuncture researches were included. The  research status  on neural tracing technique  for acupuncture researches would be analyzed from the aspects of acupuncture points, meridians, acupoint-visceral correlation and chemical feature.  Results:  Ninety-two  researches  were  included  after  electronic  searching.  The  neural  tracing technique  had been used in the field of acupuncture for almost 34 years (1983-2007). The studies mainly focused  on  the  innervations  of  acupuncture  points  and  meridians,  the  neuroanatomical  correlation  of acupuncture points and visceral, the  chemical feature  of  acupuncture  points and the other aspects. Rats, rabbits and cats were the commonly used animals, while SD rats were the most frequently used ones, which took up to 54.3% (50/92).  HRP and CTB were the mainly applied neural tracers, and the percentage were 55.4% (51/92) and 18.5%(17/92), respectively. Acupuncture points were the most commonly used positions for injection, with a percentage of 53.3% (49/92). Among all  the 63 acupuncture points, ST36 (Zusanli) was the most frequently used acupuncture point, which accounted for 17.5% (11/63). The survival time for animals  was  range  from  1  day  to  12  weeks.  About  43.5%  (40/92)  researches  perfused  with  4% paraformaldehyde, which had took up the largest  portion. Besides, the main neural labeling were neurons and nerve fibers. Conclusions: Over 30 years, the neural tracing technique has been widely applied in the morphological  studies of acupuncture. By using this technology, the innervations of acupuncture points and meridians can be revealed, and the neuroanatomical correlation between acupoint and visceral can also be illustrated.  Besides,  by  analyzing  the  neural  pathways  and  the  chemical  feature,  the  ways  in  which acupuncture may effect can be further obtained. These can not only promote the further development of the acupuncture  morphological  research,  but  also  provide  the  neuroanatomical  evidences  for  the  targeted selection of acupuncture points for clinical treatment.

Key words: acupuncture, neural tracing technique, morphology, neural pathway