CHEN Lizhen, KAN Yu, WANG Yili, ZHANG Xiaoning, WANG Xiaoyu, HE Wei, JING Xianghong 

（Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700）

Abstract:  Objective:  Transcutaneous  electrical  acupuncture  stimulation  (TEAS)  has  been gradually applied in clinic for its easy-operation, non-invasive and painless procedures.Increasing evidence  has  demonstrated  that  TEAS  are  effective  in  regulating  some  disorders  instead  of inserting needles.Previous studies have shown that local cutaneous nerve fibers and mast cells responded to manual acupuncture (MA).However, the reaction of TEAS remains unknown. The aim of this study was to investigate the local response of TEAS in Hegu (LI4) acupoint. Methods:TEAS was applied in left LI4 of rats, while the contralateral LI4 of the same rats was as a nonstimulated control. Immunohistochemistry analyses were carried out to observe the mast cells by tryptase antibody and nociceptive neuropeptides by calcitonin gene-related peptide (CGRP) or substance  P  (SP)  in  the  LI4  area.The  co-expression  between  CGRP  or  SP  and  mast  cells  was observed as well. Mast cells were also labeled with serotonin (5-HT) primary antibodies to observe their  co-expression.Furthermore,mast  cells  were  stained  by  toluidine-blue  for  observing morphological  changes  and  cell  counting.  Results:  The  results  showed  that  CGRP  and  SP immune-reactive nerve fibers（CGRP-IR  or  SP-IR）of LI14 were expressed more highly after TEAS than that of the non-stimulated control. The CGRP-IR or SP-IR fibers distributed in intraepidermis and dermis and most of them concentrated in local dermis.There were a few intact mast cells labeled by tryptase located in dermis in the control while deformed and aggregated mast cells distributed near the CGRP-IR or SP-IR nerve fibers after TEAS.In addition, some of mast cells aggregated near the blood vessels with degranulation of 5-HT granules after TEAS.The number of mast  cells  and  the  degranulation  rate  significantly  increased  as  well.  Conclusion:  The  results indicated  an  “acupuncture-like”  reaction  that local higher expression of CGRP and SP-IR nerve fibers responded to TEAS at L14. In addition, mast cells aggregated near the nerve fibers and blood vessels with degranulation of 5-HT after TEAS.

Key words: Acupuncture, LI14, Transcutaneous electrical acupoint stimulation, Calcitonin generelated peptide, Substance P, Mast cells, Serotonin