Comparison of Sensory and Motor Innervation Between the Acupoints LR3 and LR8 in the Rat With Regional Anatomy and Neural Tract Tracing.

Dongsheng Xu,Jia Wang,Ling Zou,Jingjing Cui,Yating Guo,Wenjie Zhang,Wanzhu Bai,Jieying Liao,Yi Shen,Yuqing Wang,Yuxin Su

doi:10.3389/fnint.2021.728747

Abstract

ObjectiveThis study aimed to investigate the sensory and motor innervation of “Taichong” (LR3) and “Ququan” (LR8) in the rat and provide an insight into the neural relationship between the different acupoints in the same meridian.MethodsThe LR3 and LR8 were selected as the representative acupoints from the Liver Meridian and examined by using the techniques of regional anatomy and neural tract tracing in this study. For both acupoints, their local nerves were observed with regional anatomy, and their sensory and motor pathways were traced using neural tract tracing with single cholera toxin subunit B (CTB) and dual Alexa Fluor 594/488 conjugates with CTB (AF594/488-CTB).ResultsUsing the regional anatomy, the branches of the deep peroneal nerve and saphenous nerve were separately found under the LR3 and LR8. Using single CTB, the sensory neurons, transganglionic axon terminals, and motor neurons associated with both LR3 and LR8 were demonstrated on the dorsal root ganglia (DRG), spinal dorsal horn, Clarke’s nucleus, gracile nucleus, and spinal ventral horn corresponding to their own spinal segments and target regions, respectively. Using dual AF594/488-CTB tracing, it was shown that the sensory and motor neurons associated with LR3 were separated from that of LR8.ConclusionThis study demonstrates that LR3 and LR8 are innervated by different peripheral nerves, which originated from or terminated in their corresponding spinal segments and target regions independently through the sensory and motor pathways. These results provide an example for understanding the differential innervation between the different acupoints in the same meridian.

Highlights

The two representative acupoints on the hind limbs namely “Taichong” (LR3) and “Ququan” (LR8) are attributed to the Liver Meridian of Foot-Jueyin in the traditional acupuncture theory (Cheng, 1987; Liang, 2005)
In order to reveal the differential innervation between LR3 and LR8 from the peripheral nervous system (PNS) to the central nervous system (CNS), their neural characteristics were systematically examined by the techniques of regional anatomy and neural tract tracing on the experimental rats
According to our previous studies, single cholera toxin subunit B (CTB) and dual Alexa Fluor 594/488 conjugated with CTB (AF594/488CTB) were selected for neural tract tracing in this study (Wang et al, 2018; Cui et al, 2019; Wang H. et al, 2019; Zhang et al, 2021)

Summary

Introduction

The two representative acupoints on the hind limbs namely “Taichong” (LR3) and “Ququan” (LR8) are attributed to the Liver Meridian of Foot-Jueyin in the traditional acupuncture theory (Cheng, 1987; Liang, 2005). Both of the acupoints have been located more precisely at the level of the regional anatomy in modern acupuncture science, their innervation was mainly introduced from the perspective of the peripheral nervous system (PNS) and less involved in the central nervous system (CNS; White and Editorial Board of Acupuncture in Medicine, 2009; Langevin et al, 2010; Cheng, 2011; Dorsher, 2017). Dual AF594/488-CTB are preferentially used in pair to retrogradely trace the sensory and motor neurons for identifying the neuronal correlation between the different acupoints or between the acupoint and its corresponding visceral organ (Cui et al, 2013b; Wang H. et al, 2019; Zhang et al, 2021)

Methods

Results

Discussion

Conclusion