Sinha Rakesh Kumar, Aggarwal Yogender
Dept. of Biomedical Instrumentation, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India.
Iran Biomed J. 2007 Jan;11(1):33-9.
Serotonin is believed as an important factor in brain function. The role of serotonin in cerebral psycho-patho-physiology has already been well established. However, the function of serotonin antagonist in anesthetized subjects under hyperthermia has not been studied properly.
Experiments were performed in three groups of urethane-anesthetized rats, such as: (i) control group, (ii) whole body hyperthermia group and (iii) p-CPA (para-Chlorophenylalanine) pretreated hyperthermia group. Hyperthermia was produced by subjecting the rats to high ambient temperature of 38 +/- 1 degrees C (relative humidity 45-50%). Each group was divided for EEG (electroencephalogram) study and for determination of edematous swelling in the brain.
Urethane anesthetized rats under hyperthermia show highly significant reduction in their survival time. The body temperature recorded during the hyperthermia was observed with significant and linear rise with marked increase in brain water content, which was analyzed just after the death of the subjects. The results of the electroencephalographic study in urethane-anesthetized rats recorded before death indicate that brain function varies in systematic manner during hyperthermia as sequential changes in EEG patterns were observed. However, a serotonin antagonist, p-CPA pretreatment increases the survival time with significant reduction in edematous swelling in brain but it does not affect the relationship between the core body temperature and the brain cortical potentials as observed in urethane anesthetized subjects exposed to whole body hyperthermia. The core body temperature in p-CPA pretreated rats show non-linear relationship with respect to the exposure time as it was observed in drug untreated subjects.
The findings of the present study indicate that although pretreatment of p-CPA in rats has a marked correlation between the extravasations of the blood-brain barrier under hyperthermia but shows minimum effect on the EEG in a model of hyperthermia under irreversible anesthesia.
血清素被认为是大脑功能中的一个重要因素。血清素在大脑心理病理生理学中的作用已经得到充分证实。然而，血清素拮抗剂在体温过高的麻醉受试者中的功能尚未得到充分研究。
对三组氨基甲酸乙酯麻醉的大鼠进行实验，即：（i）对照组，（ii）全身高温组和（iii）对氯苯丙氨酸（p-CPA）预处理的高温组。通过将大鼠置于38±1摄氏度的高环境温度（相对湿度45-50%）下产生高温。每组再分为进行脑电图（EEG）研究和测定脑内水肿肿胀两组。
高温下氨基甲酸乙酯麻醉的大鼠存活时间显著缩短。高温期间记录的体温呈显著线性上升，脑含水量显著增加，在动物死亡后立即进行分析。对死亡前记录的氨基甲酸乙酯麻醉大鼠的脑电图研究结果表明，在高温期间大脑功能呈系统性变化，因为观察到脑电图模式有顺序性改变。然而，血清素拮抗剂p-CPA预处理可延长存活时间，显著减轻脑水肿，但不影响核心体温与脑皮质电位之间的关系，这与全身高温下的氨基甲酸乙酯麻醉受试者的情况相同。与未用药的动物相比，p-CPA预处理大鼠的核心体温与暴露时间呈非线性关系。
本研究结果表明，尽管大鼠中p-CPA预处理与高温下血脑屏障的渗漏有显著相关性，但在不可逆麻醉下的高温模型中对脑电图的影响最小。
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