Objective To observe the peripheral and central neural connection of acupoint "Hegu"(LI4)

"Neiguan"(PC6)

"Futu"(LI18) and the thyroid gland(TG) region with fluorescence double-labelling method.Methods Thirty male Wistar rats were divided into LI4-LI18 group

PC6-LI18 group

TG-LI18 group

LI4-TG group

and PC6-TG group

with 6 rats in each.Fluorescence dyes Propidium Iodide(PI

10μL) and Bisbenzimide(Bb

10μL) were

separately

injected into those acupoints mentioned above and the TG region.Sixty hours after PI-injection and 12 hours after Bb-injection

the rats under deep anesthesia were transcardiacally perfused with PBS containing 4% polyoxymethylene

followed by taking the spinal cord and dorsal root ganglia(DRGs) of the cervical segments(C1-C8) and thoracic 1(T1) segment.Fluorescent single-and dual-labeled cells of the sliced DRGs and cervical spinal cord were observed by fluorescence microscope.Results 1) All PI-and Bb-labeled cells were found to distribute in DRGs from C1-T1 segments.PI single-labeled cells from LI4 and PC6 mainly distributed in DRGs from C4 to C8.Bb single-labeled cells from LI18 and TG region distributed in DRGs from C1-C6.2) Dual-labeled cells in the LI4-LI18 group

PC6-LI18 group

LI4-TG group

and PC6-TG group distributed in DRGs from C3 to C7

suggesting bifurcate peripheral processes of the cervical DRG neurons to innervate LI18

LI4

PC6 and the TG region.And the dual-labeled cells of the TG-LI18 group distributed mainly in DRGs from C1 to C4.3) A small number of single-labeled neurons(about 8% of total labeled cells in DRGs)and only several dual-labeled neurons were found in the anterior horn of the cervical spinal cord.Conclusion LI18

LI4 and PC6 and the thyroid gland have the same peripheral cells in DRGs of C3-C7 segments

suggesting that the bifurcate peripheral innervation may provide an anatomic evidence for the analgesic effect of acupuncture of LI18

LI4 and PC6 on thyroidectomy.