Yang Shuai, Xu Ke, Xu Xuan, Zhu Jixiang, Jin Yinan, Liu Qi, Xu Rui, Gu Xiaoping, Liu Yue, Huang Yulin, Ma Zhengliang
Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department, Nanjing University, Nanjing, China.
Front Behav Neurosci. 2022 Apr 14;16:848232. doi: 10.3389/fnbeh.2022.848232. eCollection 2022.
This study aims to explore the regulatory effect of S-ketamine on the mechanical allodynia, anxiety-like behaviors and microglia activation in adult male rats exposed to an animal model of post-traumatic stress disorder (PTSD). The rat PTSD model was established by the exposure to single-prolonged stress (SPS), and 1 day later, rats were intraperitoneally injected with 5 mg/kg S-ketamine or normal saline, respectively. Paw withdrawal mechanical threshold was measured 2 days before, and 1, 3, 5, 7, 10, 14, 21 and 28 days after injection to assess mechanical allodynia in the SPS-exposed rats. For anxiety-like behaviors, the open field test and elevated plus maze test were performed at 7 and 14 days after S-ketamine treatment in the SPS-exposed rats, respectively. SPS-induced rats presented pronounced mechanical allodynia and anxiety-like behaviors, which were alleviated by S-ketamine treatment. After behavioral tests, rats were sacrificed for collecting the anterior cingulate cortex (ACC), prefrontal cortex (PFC), dorsal striatum, and periaqueductal gray (PAG). Protein levels of TNF-α, IL-1β, p-NF-κB, and NF-κB in brain regions were examined by Western blot. In addition, microglia activation in each brain region was determined by immunofluorescence staining of the microglia-specific biomarker Iba-1. Interestingly, pro-inflammatory cytokines were significantly upregulated in the dorsal striatum and PAG, rather than ACC and PFC. Activated microglia was observed in the dorsal striatum and PAG as well, and upregulated p-NF-κB was detected in the dorsal striatum. Inflammatory response, phosphorylation of NF-κB and microglia activation in certain brain regions were significantly alleviated by S-ketamine treatment. Collectively, S-ketamine is a promising drug in alleviating mechanical allodynia, anxiety-like behaviors, and pro-inflammatory responses in discrete brain regions in a model of PTSD.
本研究旨在探讨S-氯胺酮对创伤后应激障碍（PTSD）动物模型成年雄性大鼠机械性痛觉过敏、焦虑样行为和小胶质细胞激活的调节作用。通过单次长时间应激（SPS）建立大鼠PTSD模型，1天后，大鼠分别腹腔注射5 mg/kg S-氯胺酮或生理盐水。在注射前2天以及注射后1、3、5、7、10、14、21和28天测量爪部退缩机械阈值，以评估SPS暴露大鼠的机械性痛觉过敏。对于焦虑样行为，分别在S-氯胺酮处理后的第7天和第14天对SPS暴露大鼠进行旷场试验和高架十字迷宫试验。SPS诱导的大鼠表现出明显的机械性痛觉过敏和焦虑样行为，而S-氯胺酮处理可使其减轻。行为测试后，处死大鼠以收集前扣带回皮质（ACC）、前额叶皮质（PFC）、背侧纹状体和导水管周围灰质（PAG）。通过蛋白质免疫印迹法检测脑区中TNF-α、IL-1β、p-NF-κB和NF-κB的蛋白水平。此外，通过小胶质细胞特异性生物标志物Iba-1的免疫荧光染色确定每个脑区的小胶质细胞激活情况。有趣的是，促炎细胞因子在背侧纹状体和PAG中显著上调，而在ACC和PFC中则不然。在背侧纹状体和PAG中也观察到激活的小胶质细胞，并且在背侧纹状体中检测到p-NF-κB上调。S-氯胺酮处理可显著减轻某些脑区的炎症反应、NF-κB磷酸化和小胶质细胞激活。总体而言，S-氯胺酮是一种有前景的药物，可减轻PTSD模型中离散脑区的机械性痛觉过敏、焦虑样行为和促炎反应。
