Table_1_Sex differences in hippocampal β-amyloid accumulation in the triple-transgenic mouse model of Alzheimer’s disease and the potential role of local estrogens.DOCX

IntroductionEpidemiological studies show that women have a higher prevalence of Alzheimer’s disease (AD) than men. Peripheral estrogen reduction during aging in women is proposed to play a key role in this sex-associated prevalence, however, the underlying mechanism remains elusive. We previously found that transcription factor early growth response-1 (EGR1) significantly regulates cholinergic function. EGR1 stimulates acetylcholinesterase (AChE) gene expression and is involved in AD pathogenesis. We aimed to investigate whether the triple-transgenic AD (3xTg-AD) mice harboring PS1M146V, APPSwe, and TauP301L show sex differences in β-amyloid (Aβ) and hyperphosphorylated tau (p-Tau), the two primary AD hallmarks, and how local 17β-estradiol (E2) may regulate the expression of EGR1 and AChE.MethodsWe first sacrificed male and female 3xTg-AD mice at 3–4, 7–8, and 11–12 months and measured the levels of Aβ, p-Tau, EGR1, and AChE in the hippocampal complex. Second, we infected SH-SY5Y cells with lentivirus containing the amyloid precursor protein construct C99, cultured with or without E2 administration we measured the levels of extracellular Aβ and intracellular EGR1 and AChE.ResultsFemale 3xTg-AD mice had higher levels of Aβ compared to males, while no p-Tau was found in either group. In SH-SY5Y cells infected with lentivirus containing the amyloid precursor protein construct C99, we observed significantly increased extracellular Aβ and decreased expression of intracellular EGR1 and AChE. By adding E2 to the culture medium, extracellular Aβ(l–42) was significantly decreased while intracellular EGR1 and AChE expression were elevated.DiscussionThis data shows that the 3xTg-AD mouse model can be useful for studying the human sex differences of AD, but only in regards to Ap. Furthermore, in vitro data shows local E2 may be protective for EGR1 and cholinergic functions in AD while suppressing soluble Aβ(1–42) levels. Altogether, this study provides further in vivo and in vitro data supporting the human epidemiological data indicating a higher prevalence of AD in women is related to changes in brain estrogen levels.

流行病学研究表明，相较于男性，女性患阿尔茨海默病（AD）的发病率更高。女性在衰老过程中外周雌激素的减少被认为在这一性别相关发病率中起着关键作用，然而，其潜在机制尚不明确。我们先前发现转录因子早期生长反应-1（EGR1）显著调控胆碱能功能。EGR1刺激乙酰胆碱酯酶（AChE）基因表达，并参与AD发病机制。本研究旨在探讨携带PS1M146V、APPSwe和TauP301L的 triple-transgenic AD（3xTg-AD）小鼠是否在β-淀粉样蛋白（Aβ）和过度磷酸化tau蛋白（p-Tau）这两项AD的主要标志物上表现出性别差异，以及局部17β-雌二醇（E2）可能如何调节EGR1和AChE的表达。

方法：我们首先在3至4个月、7至8个月和11至12个月龄时处死雄性和雌性3xTg-AD小鼠，并测量海马复合体中Aβ、p-Tau、EGR1和AChE的水平。其次，我们将含amyloid precursor protein construct C99的慢病毒感染SH-SY5Y细胞，并在给予或不给予E2的情况下进行培养，我们测量了细胞外Aβ和细胞内EGR1及AChE的水平。

结果：与雄性相比，雌性3xTg-AD小鼠的Aβ水平更高，而两组均未发现p-Tau。在感染含amyloid precursor protein construct C99的慢病毒的SH-SY5Y细胞中，我们观察到细胞外Aβ显著增加，而细胞内EGR1和AChE的表达降低。通过向培养液中添加E2，细胞外Aβ(l-42)水平显著降低，而细胞内EGR1和AChE的表达升高。

讨论：这些数据表明，3xTg-AD小鼠模型可用于研究AD的人类性别差异，但仅限于Aβ方面。此外，体外数据表明，局部E2可能对AD中的EGR1和胆碱能功能具有保护作用，同时抑制可溶性Aβ(1-42)水平。总之，本研究提供了进一步的体内和体外数据，支持人类流行病学数据，即AD在女性中的发病率较高与大脑雌激素水平的变化有关。