Analgesic Effects of Preliminary Microwave Irradiation of an Acupuncture Point on Visceral Pain in Mice

We studied analgesic effects provided by irradiation of an acupuncture point (AP), E36, in mice by low-intensity microwaves. Irradiation sessions preceded induction of visceral pain under conditions of the acetate test, AcT (i.p. injection of 0.08 ml of 2% acetic acid solution). Effects of irradiation in two modes, (1) with amplitude modulation and variation of the frequency within a wide range, 30 to 300 GHz, and (2) with a stable frequency, 61 ± 4 GHz, were examined. In different animal groups, the AcT was carried out either immediately or with 10- and 20-min-long delays after microwave irradiation of the AP. Analgesic effects were observed in all irradiated groups of mice. Irradiation of the AP in mode 2 provided somewhat higher levels of analgesia. Decreases in the durations of manifestations of the pain reaction in animal groups with AcT applied immediately and with 10- and 20-min-long delays after the microwave influence upon the AP in modes 1 and 2 were 26.7, 46.2, and 52.6% vs. 20.7, 55.4, and 75.0%, respectively. Thus, irradiation of the AP by low-intensity microwaves, which precedes the initiation of visceral pain, provides induction of considerable analgesic effects.