雌二醇对动情间期切除卵巢母羊黄体生成素分泌脉冲的抑制作用

动情间期母羊切除卵巢并皮下植入持续释放的E_2后,平均LH基础分泌水平和LH脉冲幅高比对照组显著减低,LH脉冲频率无明显改变。LH的平均基础分泌水平和脉?中幅高显著相关。表明植入E_2对垂体LH分泌的抑制作用主要是抑制LH对GnRH的反应,作用部位在垂体,不在下丘脑。LH基础分泌水平的下降,亦可能是E_2的抑制作用所致。

Suppressive effect of estradiol (E2)on pulsatile release of luteinizing hormone (LH) in ovariectomized ewes during anestrus

Twelve ewes were ovariectomized during anestrus and randomly allocated in to two groups. Experimental group was implanted with E_2, and control group was not. Jugular blood samples were drawn every 5 to 10 minutes through an indwelling jugular cannula for 8 to 9 hous. The plasma samples were radioimmunoassayed for LH. The mean LH basal level (MBL) and pulse amplitude (PA) in experimental group were significantly lower than those in control group, hut the LH pulse frequency was not. There was a positive relationship between MBL and PA. It is. concluded that implanted E_2 suppresses LH release at pituitary level, mainly by blocking the reponse of LH to Gn RH, and that the decrease of MBL probably is due to the suppressive effect of E_2.