Rogalska Justyna, Kang Peng, Wotherspoon Wendy, Macleod Malcolm R, Lai Maggie
Department of Animal Physiology, Institute of General and Molecular Biology, N. Copernicus University, ul. Gagarina 9, 87-100 Toruń, Poland.
Neurosci Lett. 2009 Jan 30;450(2):196-200. doi: 10.1016/j.neulet.2008.11.033. Epub 2008 Nov 18.
Brief periods of neonatal asphyxia are frequently observed. Within the CNS, the hippocampus is known to be particularly vulnerable to the damaging effects of hypoxia/ischaemia. The hippocampus contains the highest concentration of both mineralocorticoid (MR) and glucocorticoid (GR) receptors and the balance between MR/GR activation influences cell birth and death. MR occupation appears to promote prosurvival actions, while GR overactivation favours neurodegeneration. It has been widely recognized that core body temperature is a critical determinant of the severity of hypoxic-ischemic brain injury; indeed, hyperthermia exacerbates the degree of damage. Therefore, the aim of the present investigation was to study the effect of elevated body temperature in newborn rats under control conditions or during neonatal exposure to a critical anoxia, on changes of MR and GR mRNA expression in the rat hippocampus. 2-day-old rats were exposed to anoxia in 100% nitrogen atmosphere. Rectal temperature was kept at 33 degrees C (typical for the rat neonates), or elevated to a level typical for febrile (39 degrees C) adults. Control rats were exposed to atmospheric air under the respective thermal conditions. The changes in MR and GR mRNA expression in hippocampus were examined 24h after exposure. Our data show that hyperthermia with or without added anoxia, causes induction of MR mRNA expression in neonatal rat hippocampus without any effect on GR mRNA expression. We suggest this elevation of MR plays an important role in modulating the survival of neurons in the injured hippocampus.
新生儿窒息的短暂发作经常可见。在中枢神经系统中，海马体已知特别容易受到缺氧/缺血的损伤作用影响。海马体中盐皮质激素（MR）和糖皮质激素（GR）受体的浓度最高，MR/GR激活之间的平衡影响细胞的生和死。MR的占据似乎促进促生存作用，而GR的过度激活则有利于神经变性。人们已经广泛认识到，核心体温是缺氧缺血性脑损伤严重程度的关键决定因素；事实上，体温过高会加剧损伤程度。因此，本研究的目的是研究在对照条件下或新生儿暴露于严重缺氧期间，新生大鼠体温升高对大鼠海马体中MR和GR mRNA表达变化的影响。将2日龄大鼠置于100%氮气环境中缺氧处理。直肠温度保持在33摄氏度（大鼠新生儿的典型温度），或升高到发热成人的典型温度（39摄氏度）。对照大鼠在各自的热条件下暴露于大气空气中。暴露24小时后检查海马体中MR和GR mRNA表达的变化。我们的数据表明，无论有无额外缺氧，体温过高都会导致新生大鼠海马体中MR mRNA表达的诱导，而对GR mRNA表达没有任何影响。我们认为MR的这种升高在调节受损海马体中神经元的存活方面起着重要作用。
