Giordano A L, Siegel H I, Rosenblatt J S
Institute of Animal Behavior, Rutgers University, Newark, N.J.
Neuroendocrinology. 1989 Sep;50(3):248-58. doi: 10.1159/000125230.
Terminating the pregnancies of female rats on day 16 (D 16) by hysterectomy and ovariectomy (HO) and administering estradiol benzoate (EB) systemically or centrally into the medial preoptic area (MPOA) stimulates the onset of maternal behavior 48 h later. Since estrogen's effects are mediated through its intracellular receptors, the present studies measured nuclear and cytosol estrogen receptor concentrations in the POA and hypothalamus (HYP) of female rats during the 48 h when estrogen is active in stimulating maternal behavior. A low dose of EB (5 micrograms/kg) was used which was effective in stimulating maternal behavior in D16HO females but not in nonpregnant HO females of two types. In D16 animals there was a significantly higher concentration of nuclear receptors in the POA than in the HYP at time 0 (before HO and EB) but thereafter levels were similar in the two areas: nuclear receptor levels rose between 6 and 24 h after which they declined. In nonpregnant females, nuclear receptor levels at time 0 were low in both brain regions, rose significantly between 0 and 24 h, and significantly declined between 24 and 48 h similar to the D16 females. There were minimal differences in cytosol receptor levels among all groups at any time. Results from additional groups, nonpregnant HO females given 100 micrograms/kg EB and D16H animals (females whose pregnancies were terminated by hysterectomy only and their ovaries left intact), both of which exhibit maternal behavior at 48 h, support the idea that a high level of nuclear estrogen receptors in the POA followed by a sustained high level is necessary for estrogen stimulation of maternal behavior.
在第16天（D16）通过子宫切除术和卵巢切除术（HO）终止雌性大鼠的妊娠，并将苯甲酸雌二醇（EB）全身或经中枢给药至内侧视前区（MPOA），48小时后可刺激母性行为的开始。由于雌激素的作用是通过其细胞内受体介导的，因此本研究测量了在雌激素刺激母性行为活跃的48小时内，雌性大鼠视前区（POA）和下丘脑（HYP）中核雌激素受体和胞质雌激素受体的浓度。使用了低剂量的EB（5微克/千克），该剂量可有效刺激D16HO雌性大鼠的母性行为，但对两种类型的未孕HO雌性大鼠无效。在D16动物中，在时间0（HO和EB之前）时，POA中的核受体浓度显著高于HYP，但此后两个区域的水平相似：核受体水平在6至24小时之间上升，之后下降。在未孕雌性大鼠中，两个脑区在时间0时的核受体水平都很低，在0至24小时之间显著上升，在24至48小时之间显著下降，与D16雌性大鼠相似。在任何时候，所有组之间的胞质受体水平差异极小。另外两组的结果，即给予100微克/千克EB的未孕HO雌性大鼠和D16H动物（仅通过子宫切除术终止妊娠且卵巢保留完整的雌性大鼠），两者在48小时时均表现出母性行为，支持了这样一种观点，即POA中高水平的核雌激素受体随后持续高水平对于雌激素刺激母性行为是必要的。
