Fig. 1
A mechano-electrical acupuncture (MEA) instrument a Three-dimensional images of the MEA. b Control board. Two pairs of mechanical and electrical acupuncture drive circuits were mounted on printed circuits boards. c Stimulation unit. A vibrator was combined with electrodes and a rubber grommet was fixed to the needle at a distance of 3 mm from the tip for controlling the depth of acupuncture needle insertion. d Stimulation mode and measurement of intensity or frequency during mechanical or electrical stimulation. In mechanical acupuncture (MA) mode, the needles were vibrated for 6 s every 30 s for a total of 10 min. For electrical acupuncture (EA) mode, electrical stimulation (2 Hz, 0.5 mA, 0.1 ms, triangular pulses) was applied to the needles for 10 min. Mechanical force (middle panel) and electrical pulse (lower panel) measured by a force transducer and an oscilloscope, respectively. e, f Measurement of 22-kHz ultrasonic vocalizations for each 2 min before (Base) and during acupuncture treatments (Acup). Representative 22-kHz USVs during acupuncture treatment (e). Base, baseline; Acup, acupuncture. The numbers of 22-kHz USVs during acupuncture treatments (f). The data were calculated by subtracting the number of basal USVs (before stimulation) from that of the USVs during acupuncture treatment. *p < 0.05 vs. Con; Con, handling only without acupuncture, n = 6; EA, electroacupuncture at neurogenic spots, n = 6; MA, mechanical acupuncture at neurogenic spots, n = 6; MA + EA, combined treatment of MA and EA, n = 6