[Involvement of oxytocin in spinal cord in acupuncture analgesia]

The influence of intrathecal injection of oxytocin (OT), anti-OT serum (AOTS) and naloxone on pain threshold and electroacupuncture (EA) analgesia in rats was investigated. The tail-flick induced by potassium iontophoresis was used to measure the pain threshold. The increase in pain threshold was observed within 70 min after OT injection (100 ng), and it was much more effective than that of the ACSF injection (P less than 0.001). The OT administration could enhance the EA analgesia. This effect was of dose-related. Although injection of AOTS did not affect the pain threshold, it diminished EA analgesia. Furthermore, injection of naloxone did not influence the action of OT on EA analgesia. Our results showed that OT in spinal cord plays an important role in the EA analgesia, and its effects is independent of endogenous opiate peptides.