Effects of acute hypobaric hypoxia on abilities of learning and memory, the level of nitric oxide and endothelin-1 in hippocampus of mice

Abstract

Objective To examine the effects of acute hypobaric hypoxia on abilities of learning and memory, the water content in brain, the level of nitric oxide(NO) and endothelin-1(ET-1) in hippocampus of mice. Methods The acute hypobaric hypoxia environment were made by putting the mice in a hypobaric chamber simulated at altitude of 6 000 meters for 8 hours.The capabilities of learning and memory of mice were detected by Morris water maze test.The content of water in hippocampus were examined by measuring the ratio of dry/wet weight, and the level of NO and ET-1 in brain was detected by colorimetric method. Results Morris water maze test showed that the mean escape latency of mice in the hypobaric hypoxia group were longer than that in the normobaric normoxia group((44.60±7.80)s vs (26.39±8.44)s, P<0.01), and the target quadrant residence time were decreased((19.78±2.74)s vs (22.98±6.14)s, P<0.05). Compared with the normobaric normoxia group(NO: (2.37±1.07)μmol/gProt, ET-1: (38.87±6.17)ng/L), the water content in brain of mice in the hypobaric hypoxia group was increased(P<0.05), meanwhile, both the level of NO((4.48±1.45)μmol/gProt) and ET-1((52.09±6.75)ng/L) in brain were increased too(P<0.01). Conclusion Hypobaric hypoxia can decrease the abilities of learning and memory of mice, and these changes might be related with the increased water content and the increased level of NO and ET-1 in hippocampus of mice. Key words: Hypobaric hypoxia; Learning and memory; Nitric oxide; Endothelin-1