[Morphological study on commonly-used acupoints for thyroid surgery under acupuncture anesthesia].

Objective To study the morphologic structure,afferent projections of "Neiguan"(PC 6),"Hegu"(LI 4) and "Futu"(LI 18) acupoint regions so as to understand their underlying mechanisms in acupuncture anesthesia for thyroid surgery.Methods A total of 66 Wistar rats were used in the present study.① Horseradish peroxidase(HRP,10%,10 μL) was injected into PC 6,LI 4 and LI 18 acupoints and the thyroid area on the right side,respectively(n=6).② Propidium iodide(PI,10%,10 μL) or Bisbenzimide(Bb,5%,10 μL) was injected into above-mentioned 3 acupoints and the thyroid region on the right side,respectively(n=6).The numbers and percentages of the labeled neurons in the dorsal root ganglia(DRGs,C 1-C 8 and T 1) were observed under microscope.③ Cutaneous connexin(Cx) 43 immunoactivity of LI 18,PC 6,LI 4 and "Zusanli"(ST 36) regions and their individual non-acupoint regions(about 0.5 cm lateral to LI 18,PC 6,LI 4,and ST 36,n=12) was determined by immunohistochemistry.Results 1)HRP-labeled neurons after injection of HRP into LI 18 were found in DRGs of C 1-C 5,predominantly C 2-C 4,those from LI 4 found in DRGs of C 3-C 8,mainly C 5-C 7,those from PC 6 found in DRGs of C 3-T 1,chiefly C 5-C 8,and those from the thyroid region found in C 1-C 6,predominantly C 2-C 5,suggesting an overlap or convergence of afferent projections from the 3 acupoints and the thyroid regions being in C 3-C 5.2) After injection of PI into LI 18,LI 4 and PC 6,and Bb into the thyroid region,the percentages of PI-and Bb-labeled neurons in DRGs of C 1-C 8 and T 1 were from 46.4% to 50.0% and the percentages of the double labeled neurons were 3.8% in the LI 18-thyroid group,3.1% in the LI 4-thyroid group and 3.6% in the PC 6-thyroid group,respectively,suggesting a bifurcate innervation of DRG neurons between these acupoints and the thyroid region.3) In comparison with the individual non-acupuncture and non-acupoint subgroups,the immunoactivity of cutaneous Cx 43 in the LI 18,LI 4,PC 6,and ST 36 subgroups was upregulated considerably after acupuncture stimulation(P0.05).Conclusion Neurons of DRGs of C 1-C 8 and T 1 innervating "Futu"(LI 18),"Hegu"(LI 4) and "Neiguan"(PC 6) and the thyroid gland have an overlap or convergence in DRGs of C 3-C 5 and a bifurcate innervation.Acupuncture stimulation may upregulate cutaneous Cx 43 expression in the acupoint regions.