Oklahoma Center for Neuroscience, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.
Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.
Neurogastroenterol Motil. 2020 Mar;32(3):e13751. doi: 10.1111/nmo.13751. Epub 2019 Oct 31.
We previously reported that early life stress (ELS) dysregulated glucocorticoid receptor (GR) and corticotrophin-releasing hormone (CRH) expression in the central nucleus of the amygdala (CeA). Epigenetic modifications serve as memories of adverse events that occurred during early life. Therefore, we hypothesized that epigenetic mechanisms alter GR and CRH expression in the CeA and underlie chronic visceral pain after ELS.
Neonatal rats were exposed to unpredictable, predictable ELS, or odor only (no stress control) from postnatal days 8 to 12. In adulthood, visceral sensitivity was assessed or the CeA was isolated for Western blot or ChiP-qPCR to study histone modifications at the GR and CRH promoters. Female adult rats underwent stereotaxic implantation of indwelling cannulas for microinjections of garcinol (HAT inhibitor) into the CeA. After 7 days of microinjections, visceral sensitivity was assessed or the CeA was isolated for ChIP-qPCR assays.
Unpredictable ELS increased visceral sensitivity in adult female rats, but not in male counterparts. ELS increased histone 3 lysine 9 (H3K9) acetylation in the CeA and H3K9 acetylation levels at the GR promoter in the CeA of adult female rats. After unpredictable ELS, H3K9 acetylation was increased and GR binding was decreased at the CRH promoter. Administration of garcinol in the CeA of adult females, that underwent unpredictable ELS, normalized H3K9 acetylation and restored GR binding at the CRH promoter.
Dysregulated histone acetylation and GR binding at the CRH promoter in the CeA are an important mechanism for "memorizing" ELS events mediating visceral pain in adulthood.
我们之前报道过，早期生活应激（ELS）会使杏仁中央核（CeA）中的糖皮质激素受体（GR）和促肾上腺皮质激素释放激素（CRH）表达失调。表观遗传修饰可作为早期生活中发生的不良事件的记忆。因此，我们假设表观遗传机制会改变 CeA 中的 GR 和 CRH 表达，并构成 ELS 后慢性内脏痛的基础。
从出生后第 8 天到第 12 天，新生大鼠接受不可预测的、可预测的 ELS 或仅接受气味（无应激对照）。成年后，评估内脏敏感性，或分离 CeA 进行 Western blot 或 ChiP-qPCR 以研究 GR 和 CRH 启动子处的组蛋白修饰。雌性成年大鼠接受立体定向植入留置套管，用于将 Garcinol（HAT 抑制剂）微注射到 CeA 中。微注射 7 天后，评估内脏敏感性或分离 CeA 进行 ChIP-qPCR 测定。
不可预测的 ELS 增加了成年雌性大鼠的内脏敏感性，但对雄性大鼠没有影响。ELS 增加了 CeA 中的组蛋白 3 赖氨酸 9（H3K9）乙酰化，以及成年雌性大鼠 CeA 中 GR 启动子处的 H3K9 乙酰化水平。在不可预测的 ELS 后，CRH 启动子处的 H3K9 乙酰化增加，GR 结合减少。在接受不可预测的 ELS 的成年雌性大鼠的 CeA 中给予 Garcinol 后，H3K9 乙酰化正常化，并恢复了 CRH 启动子处的 GR 结合。
CeA 中 CRH 启动子处的组蛋白乙酰化和 GR 结合失调是“记忆”ELS 事件介导成年期内脏痛的重要机制。
