Arizona State University, Department of Psychology, Box 1104, Tempe, AZ 85287-1104, United States.
Neuroscience. 2013 Aug 29;246:409-21. doi: 10.1016/j.neuroscience.2013.04.027. Epub 2013 Apr 22.
Chronic stress or glucocorticoid exposure simplifies hippocampal Cornu Ammonis region 3 (CA3) apical dendritic arbors in male rats. In contrast to males, chronic stress either reduces CA3 basal branching or exerts no observable morphological effects in gonadally intact female rats. Under conditions that females display stress-induced CA3 dendritic retraction, such as that following ovariectomy, chronic exposure to 17β-estradiol or cholesterol can negate these changes. Whether glucocorticoids produce CA3 dendritic retraction in ovariectomized females and whether neuroprotection from 17β-estradiol or cholesterol is sex-specific remains unknown. The current study examined the effects of chronic glucocorticoid exposure, in conjunction with 17β-estradiol or cholesterol administration, on hippocampal CA3 dendritic complexity. Adult male and female Sprague-Dawley rats were gonadectomized and implanted with 25% 17β-estradiol in cholesterol, 100% cholesterol, or blank Silastic capsules. Rats were then assigned to either a 21-day corticosterone (CORT) drink (400μg/ml CORT, 2.4% ethanol in tap water) or tap water (Tap, 2.4% ethanol in tap water) treatment. Brains were processed for Golgi staining, and hippocampal CA3 dendritic architecture was quantified. Results showed 21-day CORT administration reduced hippocampal CA3 apical dendritic branch points, CA3 apical dendritic length, body weight gain, and adrenal weights compared to male and female control counterparts. Furthermore, male and female rats implanted with Silastic capsules containing cholesterol or 25% 17β-estradiol in cholesterol were protected from CORT-induced CA3 apical dendritic branch reduction. No effects were observed in the CA3 basal dendritic arbors. The present results demonstrate that CORT produces hippocampal CA3 dendritic retraction in gonadectomized male and female rats and that cholesterol and 25% 17β-estradiol in cholesterol prevent this dendritic simplification.
慢性应激或糖皮质激素暴露会使雄性大鼠海马角回 3 区（CA3）的顶树突分支简化。与雄性大鼠不同的是，慢性应激要么减少 CA3 基底分支，要么在未去势的雌性大鼠中没有观察到形态学效应。在雌性大鼠表现出 CA3 树突回缩的应激条件下，例如卵巢切除后，慢性暴露于 17β-雌二醇或胆固醇可以消除这些变化。糖皮质激素是否会导致去势雌性大鼠的 CA3 树突回缩，以及 17β-雌二醇或胆固醇的神经保护作用是否具有性别特异性，目前尚不清楚。本研究探讨了慢性糖皮质激素暴露与 17β-雌二醇或胆固醇给药联合对海马 CA3 树突复杂性的影响。成年雄性和雌性 Sprague-Dawley 大鼠去势并植入 25% 17β-雌二醇-胆固醇、100%胆固醇或空白硅酮胶囊。然后，将大鼠分为接受 21 天皮质酮（CORT）饮料（400μg/ml CORT，2.4%乙醇在自来水中）或自来水（Tap，2.4%乙醇在自来水中）处理的两组。对大脑进行高尔基染色，并定量海马 CA3 树突形态结构。结果显示，与雄性和雌性对照组相比，21 天 CORT 给药减少了海马 CA3 顶树突分支点、CA3 顶树突长度、体重增加和肾上腺重量。此外，植入含有胆固醇或 25% 17β-雌二醇-胆固醇的硅酮胶囊的雄性和雌性大鼠免受 CORT 诱导的 CA3 顶树突分支减少的影响。在 CA3 基底树突中没有观察到影响。本研究结果表明，CORT 会导致去势雄性和雌性大鼠海马 CA3 树突回缩，而胆固醇和胆固醇中的 25% 17β-雌二醇可防止这种树突简化。
