Zen Rika, Terashima Tomoya, Tsuji Shunichiro, Katagi Miwako, Ohashi Natsuko, Nobuta Yuri, Higuchi Asuka, Kanai Hirohiko, Murakami Takashi, Kojima Hideto
Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan.
Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan.
Front Pediatr. 2022 May 6;10:883556. doi: 10.3389/fped.2022.883556. eCollection 2022.
The pathophysiology of neonatal hypoxic-ischemic encephalopathy (HIE) has been studied in several rodent models to develop novel treatments. Although it is well known that high ambient temperature results in severe HIE, the effect of subtle changes in ambient temperature during a hypoxic-ischemic (HI) insult has not been studied. Therefore, in order to clarify the difference of pathophysiological change among the HIE models due to the influence of small changes in chamber temperature, three-step gradual change of 0.5°C each were prepared in ambient temperature during hypoxic exposure.
Blood flow in the left common carotid artery (CCA) of neonatal mice was interrupted using bipolar electronic forceps under general and local anesthesia. The mice were subsequently subjected to 10% hypoxic exposure for 50 min at 36.0, 36.5, or 37.0°C. A control group was also included in the study. The size of the striatum and hippocampus and the volume reduction rate of the hemisphere in the section containing them on the ischemic side were evaluated using microtubule associated protein 2 (MAP2) immunostaining. The accumulation of Iba1-positive cells was investigated to assess inflammation. Additionally, rotarod and open-field tests were performed 2 weeks after HI insult to assess its effect on physiological conditions.
MAP2 staining revealed that the higher the temperature during hypoxia, the more severe the volume reduction rate in the hemisphere, striatum, and hippocampus. The number of Iba1-positive cells in the ipsilateral lesion gradually increased with increasing temperature, and there was a significant difference in motor function in the 36.5 and 37.0°C groups compared with the sham group. In the open-field tests, there was a significant decrease in performance in the 37.0°C groups compared with the 36.0°C and sham groups.
Even a small gradual change of 0.5°C produced a significant difference in pathological and behavioral changes and contributed to the accumulation of Iba1-positive cells. The arrangement of ambient temperature is useful for creating a rodent model with the appropriate severity of the targeted neuropsychological symptoms to establish a novel therapy for HIE.
已在多种啮齿动物模型中研究了新生儿缺氧缺血性脑病（HIE）的病理生理学，以开发新的治疗方法。虽然众所周知，环境温度过高会导致严重的HIE，但尚未研究缺氧缺血（HI）损伤期间环境温度的细微变化的影响。因此，为了阐明由于舱内温度的微小变化的影响，不同HIE模型之间病理生理变化的差异，在缺氧暴露期间，将环境温度以每次0.5°C的三步逐渐变化来设置。
在全身麻醉和局部麻醉下，使用双极电子镊中断新生小鼠左颈总动脉（CCA）的血流。随后，将小鼠在36.0、36.5或37.0°C下进行10%的缺氧暴露50分钟。研究中还包括一个对照组。使用微管相关蛋白2（MAP2）免疫染色评估纹状体和海马的大小以及缺血侧包含它们的切片中半球的体积减少率。研究Iba1阳性细胞的积累以评估炎症。此外，在HI损伤后2周进行转棒试验和旷场试验，以评估其对生理状况的影响。
MAP2染色显示，缺氧期间温度越高，半球、纹状体和海马的体积减少率越严重。同侧病变中Iba1阳性细胞的数量随着温度升高而逐渐增加，与假手术组相比，36.5和37.0°C组的运动功能存在显著差异。在旷场试验中，与36.0°C组和假手术组相比，37.0°C组的表现显著下降。
即使是0.5°C的微小逐渐变化也会在病理和行为变化上产生显著差异，并导致Iba1阳性细胞的积累。环境温度的设置有助于创建具有适当严重程度的目标神经心理症状的啮齿动物模型，以建立HIE的新疗法。
