BACKGROUND Traumatic brain injury is the most common cause of death or chronic disability among people under-35-years-old. There is no effective pharmacological treatment currently existing for TBI. Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of pure oxygen in a hyperbaric chamber that is pressurized higher than 1atm. HBOT offers physiological and mechanical effects by inducing a state of increased pressure and hyperoxia. HBOT has been proposed as an effective treatment for moderate traumatic brain injury (mTBI), yet the exact therapeutic window and mechanism that underlies this effect is not completely understood. METHODS HBOT was administrated for 4 consecutive days, post a mouse closed head weight drop moderate TBI (mTBI) in 2 different time lines: immediate treatment - initiated 3h post-injury and delayed treatment - initiated 7days post-injury. Behavioral cognitive tests and biochemical changes were assessed. RESULTS The results were similar for both the immediate and the delayed treatments. mTBI mice exhibited impairment in learning abilities, whereas mTBI mice treated with HBO displayed significant improvement compared with the mTBI group, performing similar to the sham groups. mTBI mice had a decline in myelin basic protein, an increase in neuronal loss (NeuN staining), and an increase in the number of reactive astrocytes (GFAP). The HBO treated mice in both groups did not exhibit these changes and remained similar to the sham group. CONCLUSIONS The delayed HBOT has a potential to serve as a neuroprotective treatment for mTBI with a long therapeutic window. Further research is needed for fully understanding the cellular changes.

中文翻译：

---

立即和延迟高压氧疗法作为小鼠脑外伤的神经保护疗法。

背景技术脑外伤是35岁以下人群中最常见的死亡或慢性残疾原因。TBI目前没有有效的药物治疗方法。高压氧疗法（HBOT）定义为在压力高于1atm的高压舱中吸入纯氧。HBOT通过诱导压力升高和高氧状态提供生理和机械作用。HBOT已被提议作为中度创伤性脑损伤（mTBI）的有效治疗方法，但尚未完全了解导致这种作用的确切治疗窗口和机制。方法HBOT连续4天给药，在2个不同的时间轴上进行小鼠闭合头体重下降中度TBI（mTBI）后：立即治疗-受伤后3小时开始，延迟治疗-受伤后7天开始。评估行为认知测试和生化变化。结果立即和延迟治疗的结果相似。mTBI小鼠表现出学习能力受损，而用HBO处理的mTBI小鼠与mTBI组相比表现出显着改善，表现与假手术组相似。mTBI小鼠的髓鞘碱性蛋白减少，神经元丢失（NeuN染色）增加，反应性星形胶质细胞（GFAP）的数量增加。两组中经HBO处理的小鼠均未表现出这些变化，并且与假手术组相似。结论延迟的HBOT可能作为mTBI的神经保护疗法，具有较长的治疗窗口。