Effects of hyperbaric oxygen on the learning and memory and monoamine oxidase in hippocampus after microwave radiation in rats

Abstract

Objective To observe the effects of hyperbaric oxygen (HBO) on the learning and memory and monoamine oxidase in hippocampus after microwave radiation in rats. Methods One hundred male Wistar rats were randomly divided into 4 groups: the normal control group, the HBO control group, the radiation group and the HBO therapy group. The rats were exposed to microwave at a dosage of 30 mW/cm2 and treated with HBO at a pressure of 0.16 ATA, the next day after radiation, once a day and for a succession of 14 days. Changes in the learning and memory of the rats were assessed by average escape latency(MEL)in the Morris water maze at d 1, d 2, d 3, d 7, d 14 and d 21 after radiation. The monoamine oxidase activities in the hippocampus were measured by enzyme linked immunosorbent assay (ELISA) at h 6, d 7, d 14 and d 21 following radiation. Results One to 14 days after exposure to 30 mW/cm2 microwave radiation, the average escape latency (AEL) of the radiation group was significantly prolonged, as compared with that of the normal control group (P<0.05). Seven and 14 days after radiation exposure, AEL of the HBO therapy group was obviously shortened, as compared with that of the radiation group (P<0.05). No statistical significance could be noticed in AEL, when comparisons were made between the HBO group and the normal control group (P<0.05). MAO activity of the radiation group was significantly elevated at various time points, and there was statistical significance, when it was compared with that of the normal control group (P<0.05). However, statistical significance could be seen, when it was compared with that of the HBO group at the time points from 7 to 21 days (P<0.05). Furthermore, MAO activity of the radiation group failed to return to normal level at day 21. On the other hand, MAO activity of the HBO group returned to basic normal level at the time points from 7 to 21 days, and there was no statistical significance, when it was compared with that of the normal control group. However, it was significantly lower than that of the radiation group (P<0.05). Conclusions Microwave radiation at a dosage of 30 mW/cm2 could impair the learning and memory of rats, and could elevate MAO activity. HBO seemed to exert certain protective effects on brain injury induced by microwave radiation. Key words: Hyperbaric oxygen; Microwave radiation; Learning and memory; Hippocampus; Monoamine oxidase