Brain aromatase and the regulation of sexual activity in male mice

The biologically active estrogen, estradiol, has important roles in adult brain physiology and sexual behavior. A single gene, Cyp19a1, encodes aromatase, the enzyme that catalyzes the conversion of testosterone to estradiol in the testis and brain of male mice. Estradiol formation was shown to regulate sexual activity in various species, but the relative contributions to sexual behavior of estrogen arising in the brain versus gonads remained unclear. To determine the role of brain aromatase in regulating male sexual activity, we generated a brain-specific aromatase knockout (bArKO) mouse. A newly generated whole-body total aromatase knockout mouse of the same genetic background served as a positive control. Here we demonstrate that local aromatase expression and estrogen production in the brain is partially required for male sexual behavior and sex hormone homeostasis. Male bArKO mice exhibited decreased sexual activity in the presence of strikingly elevated circulating testosterone. I...具有生物活性的雌激素雌二醇（estradiol）在成年大脑生理活动与性行为中发挥重要作用。单一基因Cyp19a1可编码芳香化酶（aromatase），该酶可催化雄性小鼠睾丸与大脑内睾酮向雌二醇的转化。已有研究表明，雌二醇的生成可调控多个物种的性行为，但大脑与性腺产生的雌激素对性行为的相对贡献仍不明确。为明确大脑芳香化酶在调控雄性性行为中的作用，我们构建了脑特异性芳香化酶敲除（bArKO）小鼠。同期构建的同遗传背景的全身整体芳香化酶敲除小鼠作为阳性对照。本研究证实，大脑内局部芳香化酶的表达与雌激素生成，对雄性性行为与性激素稳态具有部分必要性。雄性bArKO小鼠在循环睾酮水平显著升高的情况下，表现出性行为减弱。……