Analgesia Induced by Microwave Irradiation of an Acupuncture Point under Conditions of Visceral Pain in Mice: Role of the Serotonergic Cerebral System

• Published in: Neurophysiology (New York) 2005-05, Vol.37 (3), p.219-224
• Main Authors: Bagatskaya, E V, Gura, E V
• Format: Article
• Language: English
• ISSN: 0090-2977; 1573-9007
• DOI: 10.1007/s11062-005-0068-5

We studied behavioral manifestations of analgesic effects induced in mice by irradiation of the E36 acupuncture point (AcP) by low-intensity microwaves under conditions of visceral pain evoked by i.p. injections of 0.08 ml of a 2% solution of acetic acid. We also examined changes in these analgesic effects resulting from a drop in the level of serotonin after i.p. injection of 300 mg/kg of a blocker of synthesis of serotonin, DL-parachlorophenylalanine (PChPhA). Two modes of irradiation were tested, with a wide frequency range (30 to 300 GHz) and amplitude modulation (mode 1) and with a stable frequency (61 ± ± 4 GHz, mode 2). Irradiation in mode 1 provided a higher level of analgesia than that in mode 2 (decreases in the duration of manifestations of the pain reaction were, on average, 35.7 and 20.4%, respectively). The level of analgesia dropped after injections of PChPhA; the durations of behavioral pain manifestations 24 h after such injections were greater than those in the group with no injections of the blocker by 41.3 and 12.1% in irradiation modes 1 and 2, respectively. The respective figures 48 h after PChPhA injections were 52.0 and 16.1%. Thus, under conditions of visceral pain, irradiation of the AcP by low-intensity microwaves provides noticeable analgesia, and the serotonergic brain system mediates the development of analgesia under the above-mentioned conditions.