Neurophysiological basis of auricular acupuncture for the the treatment of p-chlorophenylalanine-induced insomnia

Xiong-Zhi Wu

Editor-in-Chief of TMR Non-Drug Therapy.

Electroacupuncture of auricular concha area (EA-ACR) is a method of acupuncture stimulation of auricular concha area, which has been described in ancient China as well as in Egypt, Greece and Rome [1]. The traditional theory proposed that the auricle was represented by the body and internal organs, such that different body regions and organs appear on the external ear to form a humunculus of inverted fetus.In 1950s,French physician Nogier reawakened the interest in ACR by proposing a theory that there is a somatotopic and viscerotopic representation on the auricle.The distribution of auricular acupoints in the ears has a certain regularity,which like an inverted fetus[2].Disorders from a particular part of the body could be treated by the corresponding point in the ear [1,2].Since then, EA-ACR has been used to relieve pain [3, 4], ameliorate anxiety disorders and help treat sleep disorders[5,6].However there is little empirical evidence showing how this theory working.

The present study observed the effects of electroacupuncture of auricular concha area (EA-ACR) on the circadian rhythm of melatonin secretion in p-chlorophenylalanine (PCPA) induced insomnia rats. The study divided 36 male Sprague-Dawley rats randomly into three groups:12 in blank group,12 in model group,and 12 in EA-ACR group.PCPA was injected to Sprague-Dawley rats through intraperitoneal injection for 2 days to establish insomnia model.EA-ACR group was treated for 28 days.Results showed that compared with the blank group, 28-30 hours after PCPA intraperitoneal injection, the circadian rhythm of sleep and the total sleep time of model rats decreased. Compared with the model group, electrical stimulation in the ear concha region could effectively reverse the behavioral changes of rats, and increase the trend of weight growth (P =0.010), the crossing score (P = 0.014), vertical motion score (P = 0.015) and the level of plasma melatonin secretion (P = 0.020); The underlying effects of EA-ACR may be excited on the circadian rhythm of melatonin secretion. As the level of melatonin secretion in the EA-ACR group was higher than that in the model group,and the melatonin secretion rhythm in the treatment group was found to have a certain rhythm.

Melatonin is one of the important hormones that the human body participates in many physiological activities [7]. The release of melatonin is independent of the alternation of day and night.Melatonin plays an important role in regulating circadian rhythm and sleep cycle, and its release is most closely related to sleep.The present study discussed the mechanism of EA-ACR adjusted the insomnia rats and observe the effects of EA-ACR on the circadian rhythm of melatonin secretion in p-chlorophenylalanine(PCPA)-induced insomnia rats,so as to provide a scientific and practical evidence for the EA-ACR treatment in insomnia.