A New Type of Signaling Pathways as Pilomotor Lines along Skin for Transmitting Acupuncture Signals to Produce Acupuncture Effects

In our previous study, we observed a linear system consisted of sympathetic endings in the arrector pili muscles (AP muscles) along the rat skin termed sympathetic substance lines, or SSLs. After shaving the hair of the rats, the first wave of hair re-growth was not evenly distributed, but followed specific hair loop lines (HLLs). The patterns of HLL and SSL correspond with each other and also with the ＂Meridians＂ described in Chinese traditional medicine (CTM). Here I investigated in rabbits and rats whether the acupuncture signals are transmitted via the SSL/HLL, and whether the acupuncture analgesia (AA) is dependent on any peripheral mechanism. Firstly, when acupuncture was operated or phenylephrine, an agonist for α receptor, was injected into the dermis at an acupoint, a pilomotor line occurred. The course of the pilomotor line coincided with the SSL/HLL. When the skin was incised or regitin, an antagonist for α receptor, was injected into the dermis, the pilomotor line did not cross the site of incision or injection. These results directly demonstrated the process of transmission of acupuncture signals involving the pilomotor line and the sympathetic. Secondly, AA produced by acupuncture at an acupoint was significantly blocked when the skin was incised or regitin was injected into the dermis along the SSL/HLL or the Meridian. These results suggest that the factor that blocked the pilomotor line also blocked the AA and the pilomotor line related to the AA. Lastly, noradrenaline was shown to be released from the skin along the Meridian line after acupuncture; when phenylephrine was injected into an acupoint, AA was strongly simulated. All these results indicate that: 1. The transmission pathway of acupuncture signals exists in the skin, just as the Meridians described in the CTM; 2. these pathways are the SSLs/HLLs and the pilomotor lines; and 3. the pilomotor line isjust for the transmission of acupuncture signals and the transmission is dependent on the α receptor in the AP muscles, specifically the contraction of the AP muscles. Moreover, these findings suggest a new system and a new type of signal transmission in the physiology.