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

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 methods, we found that sympathetic neurovascular networks were denser in the CV 4 acupoint compared with surrounding non-acupoints. Furthermore, high resolution 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.