Shohami E, Novikov M, Horowitz M
Department of Pharmacology, Hadassah School of Pharmacy, Hebrew University, Jerusalem, Israel.
Acta Neurochir Suppl (Wien). 1994;60:443-5. doi: 10.1007/978-3-7091-9334-1_121.
Cerebral edema is one of the major consequences of head trauma (HT); its evolution may cause secondary ischemia and neuronal damage. In a closed head injury model in rats, we have shown BBB disruption and edema formation during the post traumatic period. We have previously shown that chronic exposure to moderate heat improves clinical outcome of rats subjected to HT. Long term exposure to heat results in the achievement of a stable acclimated state, characterized by a lower metabolic rate and improved heat tolerance. In the present study, we investigated the effect of chronic exposure to heat on edema formation after HT. Rats were held at 24 degrees C (CON) or 34 degrees C (ACC) for one month. Injury was then induced under ether anesthesia by a weight drop device. Four or 48 hours later, they were sacrificed for evaluation of BBB integrity (Evans blue, EB, extravasation) or edema formation (specific gravity, SG, or percent water). We found that EB uptake by the contused hemisphere was 6 fold lower in the ACC rats as compared to CON (p < 0.001). Furthermore, edema measured at 48 h by both SG and percent water methods was significantly lower in the acclimated rats (p < 0.01). We suggest that heat acclimation offers protection to rats subjected to head injury, possibly by reduction of plasma proteins extravasation.
脑水肿是头部创伤（HT）的主要后果之一；其进展可能导致继发性缺血和神经元损伤。在大鼠闭合性颅脑损伤模型中，我们已经证明在创伤后时期存在血脑屏障破坏和水肿形成。我们之前已经表明，长期暴露于适度高温可改善遭受HT大鼠的临床结局。长期暴露于高温会导致达到一种稳定的适应状态，其特征是代谢率降低和耐热性提高。在本研究中，我们调查了长期暴露于高温对HT后水肿形成的影响。将大鼠置于24摄氏度（对照组）或34摄氏度（适应组）环境中一个月。然后在乙醚麻醉下通过重物下落装置诱导损伤。4小时或48小时后，将它们处死以评估血脑屏障完整性（伊文思蓝，EB，外渗情况）或水肿形成情况（比重，SG，或含水量百分比）。我们发现，与对照组相比，适应组大鼠挫伤半球的EB摄取量低6倍（p < 0.001）。此外，通过SG和含水量百分比方法在48小时时测量的水肿在适应组大鼠中显著更低（p < 0.01）。我们认为热适应为遭受头部损伤的大鼠提供了保护，可能是通过减少血浆蛋白外渗实现的。
