Effect of 100 Hz electroacupuncture on salivary immunoglobulin A and the autonomic nervous system

BACKGROUND: A previous study has reported that low-frequency (LF) electroacupuncture (EA) influences salivary secretory immunoglobulin A (sIgA) and the autonomic nervous system (ANS). The ANS is known to control the secretion volume of sIgA; however, the effect of high-frequency (HF) EA on salivary sIgA has not been determined. We investigated whether HF EA affects salivary sIgA levels and the ANS. METHOD: Sixteen healthy subjects were randomly classified into two groups: a control group and an EA group. After a 5 min rest, subjects in the EA group received EA at 100 Hz bilaterally at LI4 and LI11 for 15 min before resting for a further 40 min post-stimulation. Subjects in the control group rested for a total of 60 min. Measurements of the ANS and sIgA levels in both groups were made before, immediately after, 20 min after, and 40 min after rest or 15 min EA treatment. HF and LF components of heart rate variability were analysed as markers of ANS function. LF/HF ratio and HF were taken as indices of sympathetic and parasympathetic nerve activity, respectively. Salivary protein concentrations and sIgA levels were determined by Bradford protein assay and ELISA, respectively. RESULTS: LF/HF ratio was significantly increased immediately after EA. HF was significantly increased at 20 min after EA and sIgA level was significantly increased at 40 min after EA. In addition, HF and salivary sIgA level were positively correlated with each another. CONCLUSIONS: HF EA exerted sequential positive effects on sympathetic nerve activity, parasympathetic nerve activity, and salivary sIgA level (immediately and after 20 and 40 min, respectively). HF EA may increase salivary sIgA levels by influencing parasympathetic nerve activity.