Morningstar Mitchell D, Lopez Katalina M, Mayfield Stefanie S, Almeida-Mancero Roberto N, Marquez Joshua, Flores Andres M, Hafer Brooke R, Estrada Edilberto, Holtzman Gwen A, Goranson Emerald V, Reid Natalie M, Aldrich Abigale R, Ghatalia Desna V, Patel Juhee R, Padilla Christopher M, Chavez Glenna J, Kelly-Roman Javier, Bhakta Pooja A, Valenzuela C Fernando, Linsenbardt David N
Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.
Alcohol Clin Exp Res (Hoboken). 2025 Feb;49(2):315-331. doi: 10.1111/acer.15503. Epub 2024 Dec 13.
In rodents, third-trimester-equivalent alcohol exposure (TTAE) produces significant deficits in hippocampal-dependent memory processes such as contextual fear conditioning (CFC). The present study sought to characterize changes in both behavior and Fos neurons following CFC in ethanol (EtOH)-treated versus saline-treated mice using TRAP2:Ai14 mice that permanently label Fos neurons following a tamoxifen injection. We hypothesized that TTAE would produce long-lasting disruptions to the networks engaged following CFC with a particular emphasis on the limbic memory system.
On postnatal day 7, mice received either two injections of saline or 2.5 g/kg EtOH spaced 2 h apart. The mice were left undisturbed until they reached adulthood, at which point they underwent CFC. After context exposure on day 2, mice received a tamoxifen injection. Brain tissue was harvested. Slides were automatically imaged using a Zeiss AxioScanner. Manual counts on a priori regions of interest were conducted. Automated counts were performed on the whole brain using the QUINT 2D stitching pipeline. Last, novel network analyses were applied to identify future regions of interest.
TTAE reduced context recall on day 2 of CFC. Fos neural density increased in the CA1 and CA3. Fos counts were reduced in the anteroventral (AV) and anterodorsal thalamus. The limbic memory system showed significant hyperconnectivity in male TTAE mice, and the AV shifted affinity toward hippocampal subregions. Last, novel regions such as a subparafascicular area and basomedial amygdalar nucleus were implicated as important mediators.
These results suggest that CFC is mediated by the limbic memory system and is disrupted following TTAE. Given the increase in CA1 and CA3 activity, a potential hypothesis is that TTAE causes disruptions to memory encoding following day 1 conditioning. Future studies will aim to determine whether this disruption specifically affects the encoding or retrieval of fear memories.
在啮齿动物中，相当于妊娠晚期的酒精暴露（TTAE）会在海马体依赖的记忆过程中产生显著缺陷，如情境恐惧条件反射（CFC）。本研究旨在利用TRAP2:Ai14小鼠（在注射他莫昔芬后永久标记Fos神经元），表征乙醇（EtOH）处理组和生理盐水处理组小鼠在CFC后行为和Fos神经元的变化。我们假设TTAE会对CFC后参与的网络产生长期破坏，尤其侧重于边缘记忆系统。
在出生后第7天，小鼠接受两次间隔2小时的生理盐水注射或2.5 g/kg EtOH注射。小鼠在不受干扰的情况下成长至成年，此时进行CFC。在第2天进行情境暴露后，小鼠接受他莫昔芬注射。采集脑组织。使用蔡司AxioScanner自动对玻片成像。对先验感兴趣区域进行手动计数。使用QUINT 2D拼接管道对全脑进行自动计数。最后，应用新的网络分析来确定未来的感兴趣区域。
TTAE降低了CFC第2天的情境回忆。CA1和CA3区域的Fos神经密度增加。前腹侧（AV）和前背侧丘脑的Fos计数减少。边缘记忆系统在雄性TTAE小鼠中显示出显著的高连接性，并且AV对海马亚区域的亲和力发生了变化。最后，新区域如束旁下区和基底内侧杏仁核被认为是重要的调节因子。
这些结果表明CFC由边缘记忆系统介导，并且在TTAE后受到破坏。鉴于CA1和CA3活性增加，一个潜在的假设是TTAE在第1天条件反射后导致记忆编码中断。未来的研究旨在确定这种中断是否特别影响恐惧记忆的编码或检索。
