Vitamin K3 Regulates Reactive Oxygen Species and Extracellular-Regulated Protein Kinase in Differentiated PC-12 Cells within a Safe Dose Range

Abstract

Objective: Acupuncture can relieve pain by acting on the mitogen-activated protein kinase (MAPK) signal pathway, which plays a critical role in the balance between hyperalgesia and inflammation. Our previous studies have suggested that acupoint injection of Vitamin K3 (Vit K3) had an intensive analgesic effect on primary dyspareunia. However, the mechanism by which Vit K3 worked on nerve cells has not been elucidated. Methods: Cell apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) changes of PC-12 cells with Vit K3 treatment, for which the concentration gradient was 0, 5, 10, 20, 40, and 60 μmol/L, were quantified by flow cytometry. The expression and phosphorylation of c-Jun N-terminal kinase, p38, and extracellular-regulated protein kinase (ERK), the three critical molecules of the MAPK pathway, were further assessed using Western blotting. Results: The level of ROS first decreased and then increased with Vit K3 at 20 μmol/L, but no change in neither apoptosis nor MMP was evident. In addition, only ERK level decreased at 20 μmol/L and the relative phosphorylation level increased. Changes in ROS were negatively correlated with the expression of ERK. Conclusions: The rapid analgesic effect of Vit K3 acupoint injection may be through the reduction of ROS in nerve cells with a small dose of Vit K3 or by influencing the expression of ERK but without damaging the nerve cells themselves.