Boureau F, Willer J C, Yamaguchi Y
Electroencephalogr Clin Neurophysiol. 1979 Sep;47(3):322-8. doi: 10.1016/0013-4694(79)90283-9.
The effects of a low frequency (2 c/sec) peripheral stimulation (electro-acupuncture, EA) on the nociceptive (R2) response of the blink reflex elicited by supra-orbital nerve stimulation (0.1 msec, 1 shock/8 sec) were studied in 10 healthy subjects. EA stimulation produced a very significant inhibition of the reflex in 8 subjects. Double-blind injection of naloxone (0.8 mg) reversed this inhibition while no signiificant change was observed with placebo. These results suggest that EA stimulation induces the release of endogenous opiates.
