Fig. 1.

Effects of perineural capsaicin treatment of vagus nerve on breast cancer metastasis. We here applied perivagal capsaicin to inactivate vagal sensory nerve fibers. Female Balb-c mice were used. The cervical vagi (right (RV) or left (LV)) were exposed and freed from the carotid artery for a distance of 2–3 mm following a midline incision in the neck. Parafilm was placed around the nerve, and a cotton wool soaked in capsaicin (1%) or vehicle was placed around each vagus nerve for 30 min. One week after perivagal capsaicin application, 4T1 breast carcinoma cells (100,000 cells/mouse/0.1 ml) were injected into the right upper mammary pad. Four weeks after injection of 4T1 cells, lung tissues were removed and macroscopic metastasis were determined as described previously [27]. Student’s t test was used for statistical analysis. Animals: Sham-sham operated