Maggi R, Martini L, Piva F
Department of Endocrinology, University of Milano, Italy.
Endocr Regul. 1994 Dec;28(4):171-8.
The present experiments have been performed to analyze whether ovariectomy, performed in adult female rats, might influence the binding characteristics of hypothalamic mu binding sites. To this purpose, different groups of ovariectomized females have been killed by decapitation 1, 3, 7, 15 and 21 days after surgery, and the binding characteristics (Bmax and Kd) of the mu receptors have been determined in their hypothalami. Dihydromorphine was used as a specific mu ligand. The data obtained have been compared with those derived from the hypothalami of adult female rats in the morning of proestrus, when the density of hypothalamic mu opioid receptors reaches its highest concentration. Blood from trunk vessels was also collected for the evaluation of serum LH levels by radioimmunoassay. The results obtained have shown that one day after ovariectomy, the number of hypothalamic mu opioid binding sites is as high as that found in proestrus animals. The number of these binding sites tends to decrease on days 3, 7 and 15 after surgery. On day 21 after gonadectomy, the number of mu binding sites results to be significantly lower than that observed in the hypothalami of intact female rats in the morning of proestrus and in the hypothalami of female animals castrated since one day. The value of the Kd did not show any variation on days 1, 3, 15 and 21; however, a significant increase of this parameter (which indicates a decrease of the affinity of the ligand for its receptors) was observed on day 7 after ovariectomy.(ABSTRACT TRUNCATED AT 250 WORDS)
进行本实验是为了分析成年雌性大鼠卵巢切除术后是否会影响下丘脑μ阿片受体结合位点的特性。为此，将不同组的去卵巢雌性大鼠在手术后1、3、7、15和21天断头处死，测定其下丘脑μ阿片受体的结合特性（最大结合容量Bmax和平衡解离常数Kd）。二氢吗啡用作特异性μ配体。将获得的数据与动情前期上午成年雌性大鼠下丘脑的数据进行比较，此时下丘脑μ阿片受体密度达到最高浓度。还收集躯干血管血液，通过放射免疫测定法评估血清促黄体生成素（LH）水平。结果显示，卵巢切除术后一天，下丘脑μ阿片结合位点数量与动情前期动物的数量一样高。这些结合位点数量在术后第3、7和15天趋于减少。性腺切除术后第21天，μ结合位点数量显著低于动情前期上午完整雌性大鼠下丘脑以及术后一天去势雌性动物下丘脑的数量。Kd值在第1、3、15和21天没有变化；然而，在卵巢切除术后第7天观察到该参数显著增加（这表明配体对其受体的亲和力降低）。（摘要截断于250字）
