Sinha Rakesh Kumar
Dept. of Biomedical Instrumentation, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India.
Iran Biomed J. 2007 Apr;11(2):101-111.
This study demonstrates the changes in six different pathophysiological parameters such as body weight, body temperature, fecal pellet count, blood-brain barrier (BBB) permeability, plasma corticosterone level and emergence of hemorrhagic peptic ulcer spots due to exposure to high environmental heat in three different age groups of freely moving rats.
Each age group of rats was sub divided into three groups: (i) acute heat stress-subjected to a single exposure for four hours in the Biological Oxygen Demand incubator at 38 degrees C; (ii) chronic heat stress-exposed for 21 days daily for one hour in the incubator at 38 degrees C, and (iii) handling control groups. The data were recorded for the analyses of the changes in different parameters just after the heat exposure from acute stressed rats and on 1st, 3rd, 6th, 9th, 12th, 15th, 18th and 21st day on chronic stressed rats for body temperature, body weight, fecal pellets count. For the analysis of changes in three other parameters, BBB permeability, plasma corticosterone level and peptic ulcer spots following chronic exposure to high environmental heat, data were recorded on 22nd day for the analysis.
Analysis of variance (ANOVA-1) of the observations demonstrates a significant increase in body temperature, fecal pellet count, BBB permeability (except in adult group), plasma corticosterone level and emergence of hemorrhagic peptic ulcer spots in all three different age group of rats due to exposure to acute heat stress. However, chronic heat was found responsible for the significant reduction in body weight in weaning and young rats, increase in body temperature, number of fecal pellets excreted (in early days of chronic stress) and number of peptic ulcer spots in all three age groups of rats. At the same time, BBB extravasations were not observed in rats except very mild in weaning group.
The results of the present study indicate that the acute as well as chronic exposure to hot environment significantly alters the physiology of different organs of the body.
本研究展示了自由活动大鼠的三个不同年龄组在暴露于高温环境后，体重、体温、粪便颗粒计数、血脑屏障（BBB）通透性、血浆皮质酮水平以及出血性消化性溃疡斑点出现等六个不同病理生理参数的变化。
每个年龄组的大鼠再分为三组：（i）急性热应激组——在生物需氧量培养箱中于38℃单次暴露4小时；（ii）慢性热应激组——在培养箱中于38℃每天暴露1小时，持续21天；（iii）处理对照组。记录急性应激大鼠热暴露后以及慢性应激大鼠在第1、3、6、9、12、15、18和21天的体温、体重、粪便颗粒计数等不同参数变化的数据，用于分析。对于另外三个参数，即慢性暴露于高温环境后的血脑屏障通透性、血浆皮质酮水平和消化性溃疡斑点变化的分析，在第22天记录数据进行分析。
对观察结果的方差分析（单因素方差分析）表明，由于暴露于急性热应激，所有三个不同年龄组的大鼠体温、粪便颗粒计数、血脑屏障通透性（成年组除外）、血浆皮质酮水平以及出血性消化性溃疡斑点的出现均显著增加。然而，发现慢性热应激导致断奶和幼年大鼠体重显著下降，体温升高，所有三个年龄组大鼠排泄的粪便颗粒数量（在慢性应激早期）以及消化性溃疡斑点数量增加。同时，除断奶组有非常轻微的情况外，未在大鼠中观察到血脑屏障渗漏。
本研究结果表明，急性和慢性暴露于炎热环境会显著改变身体不同器官的生理功能。
