title: Coarse needle surface potentiates analgesic effect elicited by acupuncture with twirling manipulation in rats with nociceptive pain.
abstract: BACKGROUND
  Biomechanical phenomenon called "needle grasp" through the winding of connective tissue has been proposed as an action mechanism of acupuncture manipulation. The aim of the present study is to verify whether the needle grasp force affects the pain-relieving activity of acupuncture in the tail-flick latency (TFL) and the rat paw formalin tests.
  
  
  METHODS
  In order to make different roughness on the acupuncture needle surface, the needles with 0.2 mm-diameter were scratched using silicon carbide sandpapers with the grit numbers of 600 (mild coarse) and 200 (extra coarse). The surface roughness and rotation-induced torque of the scratched needles were then measured by atomic force microscope and Acusensor®, respectively. Rat abdominal wall tissues including insertion site of acupuncture needle were excised after 5 unidirectional rotations of the needles having various degrees of roughness, and the morphological changes of connective tissues were analyzed using hematoxylin and eosin (H-E) staining. Finally, the effects of coarse needle surface on anti-nociception induced by twirling manipulation were tested in rat TFL and formalin test.
  
  
  RESULTS
  It was observed that the rougher the needle surface, the stronger the needle grasp force and thickness of subcutaneous connective tissue while rotating. TFL increased in proportion to surface roughness of the ground needles 10 min after acupuncture into the Zusanli acupoint (ST36) on rat's legs. In the rat formalin test, the rougher needle also significantly exerted the larger analgesic effect during both early and late phases compared to non-ground normal needle.
  
  
  CONCLUSIONS
  Surface roughness of the acupuncture needle enhanced an anti-nociceptive activity of acupuncture therapy in rats, which partially supports the mechanical signaling theory through connective tissues in acupuncture manipulation.
authors.affiliation: Acupuncture and Meridian Science Research Center, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.|Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, 60611, USA.|KM Fundamental Research Division, Korea Institute of Oriental Medicine, Daejeon, 34054, Republic of Korea.
authors.forename: Sunoh
authors.initials: S
authors.lastname: Kwon
authors.affiliation: Acupuncture and Meridian Science Research Center, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.|Department of Basic Science of Korean Medicine, Graduate School, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
authors.forename: Yangseok
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Acupuncture and Meridian Science Research Center, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.|Department of Basic Science of Korean Medicine, Graduate School, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
authors.forename: Hi-Joon
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Acupuncture and Meridian Science Research Center, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea. dhhahm@khu.ac.kr.|Department of Basic Science of Korean Medicine, Graduate School, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea. dhhahm@khu.ac.kr.
authors.forename: Dae-Hyun
authors.initials: DH
authors.lastname: Hahm
mesh_terms: D015667:Acupuncture Analgesia / Q000295:instrumentation / Q000379:methods; D015669:Acupuncture Points; D015670:Acupuncture Therapy / Q000295:instrumentation / Q000379:methods*; D000818:Animals; D006801:Humans; D008297:Male; D009339:Needles; D059226:Nociceptive Pain / Q000628:therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley
keywords: Acupuncture; Analgesia; Connective tissue; Manipulation; Needle surface roughness