Decreased expression of aquaporin 4 (AQP4) in brain tissue of rats with thermoplegia is associated with encephaledema

: Objective To study the characteristics of the expression of aquaporin-4 (AQP4) in the brains and astrocytes of rats with thermoplegia. Methods Sixty healthy male Sprague-Dawley rats weighing (250±30) g were randomly divided into control group and model group. The quiet exposure method with high temperature (40DegreesCelsius) and high humidity (70%) was used to make a typical rat model of thermoplegia to monitor rectal temperature and record onset time every 10 minutes. When the temperature of stressed rats reached 42.5 DegreesCelsius, it was regarded as onset time of the disease. The rats in both groups were placed at 26DegreesCelsius with humidity 60% later. After 5-hour observation and their behavior evaluation, the rats were killed and their brain tissues were taken for measuring the water content of the tissues. The astrocytes of the rats were cultured at 37DegreesCelsius and 41DegreesCelsius. AQP4 mRNA and protein expression were detected by reverse-transcription PCR and Western blot analysis. Results Compared with the control group, the expression of AQP4 mRNA and protein were significantly lower in the model group than in the control group. Conclusion High temperature may lead to the destruction of blood-brain barrier and the down-regulation of AQP4 mRNA and protein expression in experimental rats, which can induce the occurrence and development of cerebral edema in experimental rats.