Abstract: Experiments were conducted on Kunming mice. The contents of DA,NE, 5-HT and 5-HIAA in the brain was measured with fluoresent methods. Compared with the group A of blank control without exposure to hypoxia, group B of experimental control exposed to hypoxia only once, and group D of another experimental control fed for two days after acute and repeatitive exposure to hypoxia for 4 times, the content of DA and 5-HIAA significantly increased and that of NE significantly decreased in the experimental animals, group C, acutely and repeatedly exposed to hypoxia for 4 times; the content of 5-HT significantly increased in group C in comparision with group B; while the content of the four chemicals was close to each other among group A, B, and D. These results indicate that substance of monoamines in the brain may be involved in the development of tolerance to hypoxia in acute and repeated hypoxia exposed animals.

Key words: anoxia, monoamines, brain, mice