| ObjectiveOwing to the fatigue, the decrease in human performance and increase in non-diseaseinjury and non-battle injury has become outstanding issues in man-machine-environmentsystem of naval vessels, especially in its long term navigation. Main factors such as noiseexposure, sleep deprivation and seasickness usually become common stressors. They arecombined to evoke crewmembers’ fatigue easily in the special naval environmentconditions in seagoing navigation.In this study, the animal models caused by combinedmain factors were made in rats. The parameters of electroencephalogram (EEG), auditoryfunction, praxiology, and serum biochemical indexes were observed in rats. The effectsof the long term navigation on the characteristic parameters of sound spectrum wereobserved in naval sailors. These results will provide a foundation to study evaluation,prevention and intervention, and monitor for fatigue further seen in crewmembers duringlong term navigation.Methods1. The effects of combined main factors of fatigue caused by navigation on theparameters of electroencephalogram (EEG), auditory function, praxiology, and serumbiochemical indexes in rats(1)72male rats were randomly divided into3groups: the control group, the sleepdeprivation control group and the combined factors group in both the acute and chronicexperiment.(2) Acute and chronic animal models were made in rats exposed combined mainfactors such as noise exposure, sleep deprivation and simulated seasickness.(3) Electrodes were inserted through burr holes drilled in the skull of rats, and EEGwere recorded for20min before and after the experiment so as to observe the EEGchange in rats with acute and chronic fatigue by comparing the ratio of fast waves andslow waves of EEG.(4) DPOAE amplitudes were recorded with DPOAE smart system before and after theexperiment, in order to observe the effects of the combined factors on auditory functionin rats. (5) Effects of acute and chronicle fatigue were observed on spatial learning andmemory ability in rats by measuring the escape latency with Morris Water Maze VideoAnalysis System, and on locomotors activity by recording the total distance, the centraldistance and the rest time with Locomotion Activity (Open Field) Video AnalysisSystem.(6) Blood samples were collected, and the serum biochemical indexes were determinedwith kit, including malondialdehyde, super oxide dismutase, cortical, urea nitrogen,testosterone, creative kinase and cytochrome oxidizer.2. Analysis of characteristic parameters of sound spectrum in naval sailors during longterm navigation.Voice signals were recorded in10naval sailors before and after long term navigation.The software of Pratt was used to test parameters such as fundamental frequency,intensity, and vowel formant in order to observe the effects of long term navigation at seaon characteristic parameters of sound spectrum.3. Data processingData obtained from the experiments were presented with (x s), and statisticalanalysis was made with SPSS13.0software, and group comparison with varianceanalysis.Results1. Acute and chronic animal models caused by combined main factors were made inrats.2. Effects of the combined factors on EEG were observed in rats, with the ratio of thealpha waves and beta waves decreased, while the ratio of the delta waves increased.3. DPOAE amplitudes of most frequency points were decreased in acute fatigue ratsexposed to combined factors, especially at high frequency points. No significantdifferences were observed comparing with chronic fatigue ones.4. Effects of the combined factors on rats’ behavior were observed, with the escapelatency prolonged in the Morris Water Maze test and the total distance and centraldistance decreased, while the rest time increased in locomotion activity test. Fatigueprocess could be facilitated by these changes.5. Changes of the serum biochemical indexes in rats were as follows: the content of malondialdehyde increased, while the activity of super oxide dismutase decreased; thecontent of cortisol, urea nitrogen decreased, while the content of testosterone decreased;the activity of creative kinase and the content of cytochrome oxidizer showed an up trendin both the acute and chronic experiment.6. The characteristic parameters of sound spectrum of naval sailors were analyzed. Theresults showed that the fundamental frequency, the intensity, and the vowel formantdecreased.Conclusions1. The ratio of fast waves of EEG decreased while the ratio of slow waves increased inconditions of fatigue.2. The auditory function was impaired obviously in acute fatigue rats; while theimpairment of the auditory function was not obviously seen in chronic fatigue ones.3. The spatial learning and memory ability were damaged, the central nervous systemwas depressed and therefore, the exploratory behavior was not seen obviously in ratsexposed to combined factors.4. The combined factors could promote oxidative stress in rats. As a result, theanti-oxidation capacity was attenuated, lipid peroxidation reaction improved,catabolism of protein enhanced in rats.5. The characteristic parameters of the pitch, intensity of tone, and timbre could beconsidered as sensitive indexes to identify sound of fatigue caused by navigation.6. The parameters of electroencephalogram, auditory function, praxiology, serumbiochemical indexes and sound spectrum could be considered useful to evaluate thefatigue caused by navigation. |
PDF Full Text Request