Study on reverse transsynaptic virus tracing targeting Shenmen (HT7) and heart in mice

Objective To investigate the neural connections between Shenmen (HT7)-heart and the brain by observing the tracing viruses co-labeled brain nuclear groups after injection of the pseudorabies viruses (PRV), the reverse transsynaptic virus tracer carrying different fluorescent protein genes, into the myocardium and Shenmen (HT7) point, respectively. Methods Pseudorabies virus 531 (PRV531) carrying the green fluorescent protein gene and pseudorabies virus 724 (PRV724) carrying the red fluorescent protein gene were injected into the left ventricular wall and Shenmen (HT7) point area of the left forelimb of six C57BL/6 mice, respectively. After 120 h, whole brain tissue was extracted under 4% paraformaldehyde perfusion to prepare brain sections. Neuronal co-labeling with the tracing viruses was observed under fluorescence microscopy. Results Co-labeled signals from the mouse ventricular wall and Shenmen (HT7) point region were found at all levels of the mouse central nervous areas, such as the cerebral cortex, hypothalamus, midbrain, pons, and medulla oblongata. The number of co-labeled neurons was higher in the primary motor area, the hypothalamic paraventricular nucleus, the subceruleus nucleus, and the paramedian reticular nucleus. Conclusion There is a neural connection between Shenmen (HT7), the heart, and the brain, which may be most closely related to the autonomic nervous system.