ESTRADIOL MODULATES DENSITY OF PUTATIVE OXYTOCIN RECEPTORS IN DISCRETE RAT-BRAIN REGIONS
ESTRADIOL MODULATES DENSITY OF PUTATIVE OXYTOCIN RECEPTORS IN DISCRETE RAT-BRAIN REGIONS
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DOI：
10.1159/000124680
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发表时间：
1986-01-01
影响因子：
4.1
通讯作者：
ELANDS, J
中科院分区：
文献类型：
--
作者：
DEKLOET, ER;VOORHUIS, DAM;ELANDS, J
先前的研究已经提供了证据，证明大鼠脑中两种类型的加压素（AVP）标记结合位点的离散定位，即，优先标记AVP的区域（推定的AVP受体）和标记AVP以及催产素（OT）的区域。后者的结合位点在这里被认为是推定的OT受体。在本研究中，对切除卵巢的大鼠每日皮下给予类固醇（10 µg/100 g体重）后，研究了雌二醇对大鼠脑中OT和AVP的这些假定受体位点数量的影响。在体外孵育冷冻脑切片、放射自显影和用计算机辅助密度测定法定量图像后，测定[3 H]-OT和[3 H]-AVP的特异性结合。催产素增加OT受体的数量至少4倍，在下丘脑腹内侧核，嗅结节的区域，延髓核，偶尔在终板血管器。一个较小的增加（两倍），注意到中央杏仁核，而OT受体数量减少的趋势，注意到在嗅核和腹侧下托。Escherichia coli处理允许估计[3 H]-OT-结合至显微切割的下丘脑腹内侧区域的膜部分的结合常数（Kd：1.3 nM，Bmax：19.9 fmol/mg蛋白质）。在外侧隔和孤束核中推定的AVP受体的数量不受雌二醇的影响。总之，OT受体系统受到调制雌二醇在一些离散的大脑区域，但不是在其他。这种相互作用的主要部位之一位于腹内侧核，这是一个已知含有高密度雌二醇受体的下丘脑区域，并通过超微结构、蛋白质合成、电生理学和性行为的变化对雌激素作出反应。结果表明，雌二醇可能通过增加推测的OT受体的数量而使这些过程对OT和AVP敏感。
Previous studies have provided evidence for a discrete localization of two types of vasopressin (AVP)-labeled binding sites in the rat brain, i.e., regions labeled preferentially with AVP (putative AVP receptors) and regions labeled with AVP as well as oxytocin (OT). The latter binding sites are considered here as putative OT receptors. In the present study the effect of estradiol on the number of these putative receptor sites for OT and AVP was investigated in rat brain after daily subcutaneous administration of the steroid (10 µg/100 g body weight) to ovariectomized rats. Specific binding of [3H]-OT and [3H]-AVP was determined after in vitro incubation of frozen brain sections, autoradiography and quantitation of the images with computer-assisted densitometry. Estradiol increased the number of OT receptors at least 4-fold in the ventromedial nucleus of the hypothalamus, regions of the olfactory tubercle, the nucleus accumbens and occasionally in the organum vasculosum laminae terminalis. A smaller increase (two-fold) was noted in the central amygdala, while a tendency to a decrease in OT receptor number was noted in the olfactory nucleus and the ventral subiculum. Estradiol treatment permitted an estimation of binding constants of [3H]-OT-binding to a membrane fraction of microdissected ventromedial hypothalamic region {Kd: 1.3 nM, Bmax: 19.9 fmol/mg protein). The number of putative AVP receptors in the lateral septum and in the nucleus tractus solitarii was not affected by estradiol. In conclusion, the OT receptor system is subject to modulation by estradiol in some discrete brain regions, but not in others. One of the principal sites of this interaction is located in the ventromedial nucleus, which is a hypothalamic region known to contain a high density of estradiol receptors and to respond to estrogens by changes in ultrastructure, protein synthesis, electrophysiology and sexual behavior. The results show that estradiol may sensitize these processes to OT and AVP by increasing the number of putative OT receptors.