By means of push-pull perfusion technique and the special radioimmunoassay we determined the GnRH concentration of the perfusates from preoptic area (POA) in ovariectomized (OVX) and intact (INT) female rats

to observe the influence of naloxone and electroacupuncture (EA) on the release of GnRH and β-endorphin from POA. The results show that the basic GnRH level of POA perfusate in OVX was 271. 8±77. 5pg/ml and that in INT was 52.4±11. 1pg/ml. There was a significant difference between the basic levelsof two groups (P<0.02

n = 12 ). No difference of β-endorphin basic level in OVX and INT was found. The GnRH level of POA perfusate in OVX was increased by 146.6±46. 5pg/ml (P<0.01

n = 12 ) 30 minutes after intraperitoneal administration of naloxone

but no obvious change was found in INT following naloxone administration. EA treatment had no effect on the release of GnRH and β-endorphin in both of OVX and INT. The results suggest that the negativefeedback of estrogen may be a major regulative factor of GnRH under the normal condition and after the abolition of estrogen feedback induced by ovariectomy the centrol opioid peptide might be the main regulative mechnism for GnRH.