Spatial topological analysis of sympathetic neurovascular characteristic of acupoints in Ren meridian using advanced tissue-clearing and near infrared II imaging

Abstract

Acupuncture has been used for treating various medical conditions in traditional Chinese medicine. Both manual and electro-acupuncture stimulate specific acupoints to obtain local and systemic biological effects, but the underlying mechanisms remain unclear. Here, we used three-dimensional tissue-clearing technology to study acupoints on the Ren meridian of mice to reveal the distribution, density, branching, and relationships between blood vessels and nerves. Using topological <i>Mapper</i> methods, we found that sympathetic neurovascular networks were denser in the CV 4 acupoint compared with surrounding non-acupoints. Furthermore, high resolution <i>in vivo</i> real-time vascular imaging using the near infrared-II probe LZ-1105 demonstrated increased blood flow in the CV 4 acupoint compared with neighboring non-acupoints after manual or electro-acupuncture. Consistent with earlier findings, our research indicated that acupuncture could enhance local blood flow, and our high-resolution 3D images show for the first time the important role of sympathetic neurovascular networks in the CV 4 acupoint.