Data from: Quantitative analysis of long-form aromatase mRNA in the male and female rat brain

In vitro studies show that estrogens acutely modulate synaptic function in both sexes. These acute effects may be mediated in vivo by estrogens synthesized within the brain, which could fluctuate more rapidly than circulating estrogens. For this to be the case, brain regions that respond acutely to estrogens should be capable of synthesizing them. To investigate this question, we used quantitative real-time PCR to measure expression of mRNA for the estrogen-synthesizing enzyme, aromatase, in different brain regions of male and female rats. Importantly, because brain aromatase exists in two forms, a long form with aromatase activity and a short form with unknown function, we targeted a sequence found exclusively in long-form aromatase. With this approach, we found highest expression of aromatase mRNA in the amygdala followed closely by the bed nucleus of the stria terminalis (BNST) and preoptic area (POA); we found moderate levels of aromatase mRNA in the dorsal hippocampus and cingulate cortex; and aromatase mRNA was detectable in brainstem and cerebellum, but levels were very low. In the amygdala, gonadal/hormonal status regulated aromatase expression in both sexes; in the BNST and POA, castration of males down-regulated aromatase, whereas there was no effect of estradiol in ovariectomized females. In the dorsal hippocampus and cingulate cortex, there were no differences in aromatase levels between males and females or effects of gonadal/hormonal status. These findings demonstrate that long-form aromatase is expressed in brain regions that respond acutely to estrogens, such as the dorsal hippocampus, and that gonadal/hormonal regulation of aromatase differs among different brain regions.

体外实验表明，雌激素可在两性中急性调控突触功能。这类急性效应可能由脑内合成的雌激素在体内介导，脑内雌激素的波动速度或快于循环中的雌激素。若要这一效应通过该途径实现，则对雌激素产生急性应答的脑区域应当具备合成雌激素的能力。为探究这一问题，我们采用定量实时聚合酶链反应（quantitative real-time PCR）检测了雌雄大鼠不同脑区域中雌激素合成酶芳香化酶（aromatase）的mRNA表达水平。值得注意的是，脑内芳香化酶存在两种亚型：具备芳香化酶活性的长亚型，以及功能未知的短亚型，因此我们靶向仅存在于长亚型芳香化酶的特异性序列进行检测。通过该实验方法，我们发现芳香化酶mRNA的表达水平在杏仁核中最高，其次为终纹床核（bed nucleus of the stria terminalis, BNST）与视前区（preoptic area, POA）；在背侧海马与扣带回皮层中可检测到中等水平的芳香化酶mRNA；脑干与小脑中亦可检测到该mRNA，但其表达水平极低。在杏仁核中，性腺与激素状态可调控两性的芳香化酶表达；在终纹床核与视前区中，雄性去势可下调芳香化酶的表达水平，而雌二醇对卵巢切除后的雌性个体无显著调控效应。在背侧海马与扣带回皮层中，雌雄大鼠的芳香化酶表达水平无显著差异，且性腺与激素状态对其无调控作用。本研究结果证实，长亚型芳香化酶在对雌激素产生急性应答的脑区域（如背侧海马）中均有表达，且不同脑区域的芳香化酶表达受性腺与激素的调控模式存在差异。