[Changes of releases of beta-endorphin-like immunoreactive substances and noradrenaline in rabbit's preoptic area during acupuncture analgesia].

RIA and HPLC-ECD were used respectively to detect beta-endorphin-like immunoreactive substances (beta-EPIS), noradrenaline and 3-methoxy-4-hydroxyphenyloglycol (MHPG), a noradrenaline metabolite, in the perfusate from the rabbit's preoptic area before and after 10 min of electroacupuncture (EA). It was found that, the content of beta-EPIS in the perfusate increased during acupuncture analgesia, while those of noradrenaline and MHPG decreased. A negative correlation (r = -0.831; P less than 0.05) was shown between the changes of beta-EPIS and MHPG contents during acupuncture analgesia, indicating that beta-endorphin may be related to the inhibition of noradrenaline release during acupuncture analgesia.