Specificity of Sensory and Motor Neurons Associated with BL40 and GB30 in the Rat: A Dual Fluorescent Labeling Study

Abstract

The purpose of this study is to investigate the specific innervations on “Weizhong” (BL40) and “Huantiao” (GB30) by using a dual neural tracing technique. After Alexa Fluor 488 and 594 conjugates of cholera toxin subunit B (AF488/594-CTB) were, respectively, injected into BL40 and GB30 in the same rat, the labeled sensory and motor neurons were examined in the rat's dorsal root ganglia (DRGs) and spinal cord at thoracic (T) and lumbar (L) segments with a laser scanning confocal microscope. In the cases of BL40 injection, AF488-CTB labeled sensory and motor neurons were located in L2–6 DRGs and on the mediolateral part of spinal ventral horn from L3 to L5 segments, respectively. By contrast, in the cases of GB30 injection, AF594-CTB labeled sensory and motor neurons were distributed in T13-L6 DRGs and on the anterolateral part of spinal ventral horn from L1 to L5 segments, respectively. These results indicate that the sensory and motor neurons associated with BL40 and GB30 are located in different spinal segments and regions in the nervous system, providing the neuroanatomical evidence to serve the specificity of acupoints.

Neuroanatomical Characteristics of Deep and Superficial Needling Using Li11 as An Example

“…Previous studies from our laboratory have provided experimental evidence that motor and sensory neurons in the vicinity of classical acupuncture points follow a segmental pattern in the nervous system. 14 15 17 In the present study, we have confirmed that this is also true of acupuncture point LI11, while further demonstrating that the motor neurons of the deep tissue layer spread over a greater number of spinal segments and outnumber those of the superficial tissue layer. Although the sensory neurons associated with both deep and superficial tissue layers distribute similarly across the same spinal segments, the number of sensory neurons in the superficial tissue layer is greater than that of the deep tissue layer.…”

“…It is a technical limitation that AF488-CTB cannot be used to label nerve fibres and axonal terminals like conventional CTB; 17 however, it remains an appropriate method to label sensory and motor neurons associated with acupuncture points in a retrograde manner. 14 15 Although, in the present study, the tracer was separately injected into the muscle or subcutaneous tissue in the experimental animals (through the use of a skin incision), in clinical practice the acupuncture needle will always pierce the dermal layer before reaching the muscle layer. Therefore, when evaluating the effect of deep needling, the neuroanatomical characteristics associated with both the muscle and the subcutaneous tissue layers should be considered together.…”

“…However, comparisons can be made with our previous studies of the neuroanatomical characteristics of other acupuncture points including BL57, BL40 and GB30. 14 15 …”

“… 13 In order to obtain a detailed view of the neuroanatomical characteristics of the tissue layers encountered by an acupuncture needle at variable depth, a representative acupuncture point, LI11 ( Quchi ), was selected and examined using a neural tracing technique with Alexa Fluor 488 conjugate of cholera toxin subunit B (AF488-CTB), a sensitive tracer that has successfully been used to investigate the neuroanatomical characteristics of acupuncture points. 14 15 The aim of the present study was to inject AF488-CTB into muscle or subcutaneous tissue under LI11 in rats to mimic deep and superficial needling, respectively, in order to examine the motor and sensory innervation of the muscle and subcutaneous tissue at this anatomical location.…”

Neuroanatomical Comparative Studies on the Motor and Sensory Neurons Associated with Cheonji(PC1) in the Rats

“…신경추적자들을 이용하여 특정 경혈에서 투사하는 신경계 내 표지영역들을 관찰하는 것은 침구치료의 기전을 신경해부학적으로 밝히는데 중요한 역할을 할 것으로 생각된다. 신경추적자를 이용한 연구에서는 경혈과 신경과의 관계를 신경 해부학적으로 밝히기 위하여 특정 경혈과 관련된 운동과 감각신경 세포의 영역 및 신경세포 내 신경 전달물질을 관찰하였고 3,4) 또한 서로 다른 경혈과 관련된 신경세포의 특징을 관찰하기 위하여 신경 추적자를 이용하여 다양한 연구가 진행되고 있다5) .…”