Endorphin release: a possible mechanism of acupuncture analgesia

Effects of acupuncture stimulation at different acupoints on formalin-induced pain in rats

Acupuncture is the process of stimulating skin regions called meridians or acupoints and has been used to treat pain-related symptoms. However, the pain-relieving effects of acupuncture may be different depending on acupoints. In the present study, the effects of acupuncture on behavioral responses and c-Fos expression were evaluated using a formalin test in male Sprague-Dawley rats in order to clarify the analgesic effects of three different acupoints. Each rat received manual acupuncture at the ST36 (Zusanli), SP9 (Yinlingquan) or BL60 (Kunlun) acupoint before formalin injection. Flinching and licking behaviors were counted by two blinded investigators. Fos-like immunoreactivity was examined by immunohistochemistry in the rat spinal cord. Manual acupuncture treatment at BL60 acupoint showed significant inhibition in flinching behavior but not in licking. Manual acupuncture at ST36 or SP9 tended to inhibit flinching and licking behaviors but the effects were not statistically significant. The acupuncture at ST36, SP9, or BL60 reduced c-Fos expression as compared with the control group. These results suggest that acupuncture especially at the BL60 acupoint is more effective in relieving inflammatory pain than other acupoints.

Minilaparotomy under acupuncture analgesia

Minilaparotomy was performed using acupuncture analgesia on 78 female patients seeking voluntary sterilization to determine whether this could be used as a substitute for standard analgesic sedation. In 48 women (62%) no intravenous drug medication was required, and sterilization was successfully performed using only the local anaesthetic and acupuncture electrostimulation. These patients could be discharged within one hour of operation. For a developing country with a shortage of trained anaesthetists, acupuncture analgesia could prove to be a simple, safe and economical method, especially in a rural setting.

Naloxone fails to reverse pain thresholds elevated by acupuncture: acupuncture analgesia reconsidered

We were unable to demonstrate the reversal of dental acupunctural analgesia following the injection of 0.4 mg naloxone using evoked potential methodology. Since our findings differed from those of Mayer, Price and Rafii who used pain threshold methods, we attempted to replicate their study. Subjects who demonstrated acupunctural analgesia during electrical stimulation of the LI-4 point on the hands received either 1.2 mg naloxone or normal saline under double blind conditions. Pain thresholds elevated by acupuncture failed to reverse when naloxone was given. Review of experimental design issues, other related human subjects research, and animal studies on acupunctural analgesia provided little convincing evidence that endorphins play a significant role in acupunctural analgesia. Because endorphins can be released in response to a stressor, endorphin presence sometimes correlates with acupunctural treatment in animal studies and some human studies, especially those involving pain patients. The primary analgesia elicited by acupunctural stimulation seems to involve other mechanisms.

Endogenous opiates: through 1978

The discovery of receptors in the brain for opiates and the structure of the endogenous peptides for these receptors has led to an explosion of interest in this field. The present review is the first of an annual series. It summarizes many of the highlights of research with opiate peptides published with a date of 1978 or earlier.