Role of opioid peptides of rat's nucleus reticularis paragigantocellularis lateralis (RPGL) in acupuncture analgesia.

ABSTRACT

The present study was to investigate the role of the RPGL and its endogenous opioid peptides in acupuncture analgesia (AA) using techniques of brain stimulation and lesion, microinjection, push-pull perfusion and radioimmunoassay (RIA). The results showed that electrical stimulation of the RPGL could increase the pain threshold and enhance the effect of AA, whereas lesion of the RPGL reduce the effect of AA. Microinjection of naloxone (5 micrograms/0.5ul/2min) into the RPGL could partially reverse the effect of AA and the reversal effect of naloxone was dose-dependent. The release of leu-enkephalin (LEK) and B-endorphin (B-EP) from the RPGL in the electrical acupuncture (EA) group was significantly higher than that in the control group (P < 0.05). There were positive correlations between the changes of release of LEK, B-EP and the increase of pain threshold. The results mentioned above imply that the RPGL plays an important role in AA. The activation of the RPGL and the endogenous opioid peptides within it produce an advantageous effect on AA.