Evaluation of the combined effects of noise and vibration on the levels of stress hormones and behavioral responses in animals

Abstract

Introduction. The occupation of firefighters refers to extreme activities. When performing professional tasks, firefighters are exposed to the combined effects of a complex of adverse factors, among which noise and vibration occupy an important place, while vibration significantly promotes the negative effect of noise. Noise is also one of the most common stress factors that characterize extreme conditions for firefighters. The results of experiments on animals, which are the simplest human biomodel, are of great importance in their study. Materials and methods. The study was carried out on 86 outbred white male rats of 3 months of age, weighing 230-250 g. The rats were divided into 2 groups: the first group (43 rats) was exposed to a single exposure to noise and vibration, the second group (43 rats) was exposed to daily exposure for 14 days. The procedure for vibroacoustic exposure was performed daily for 4 hours at noise and vibration levels as close as possible to the loads encountered in real conditions when firefighters perform occupational tasks. Changes in the levels of the three main stress hormones (adrenaline, noradrenaline, cortisol) and behavioral characteristics of animals were assessed using the Open Field, Elevated Plus Maze, and Porsolt Test methods. Limitations. The number of animals in the study groups should be at least 10 individuals, the spread in the initial body weight should not exceed 10%. The study was limited to the study of the main indicators of behavioral responses using 3 methods and 3 main stress hormones. Results. The data obtained indicate the vibroacoustic effect on animals to cause a change in hormone levels and indicators of behavioral reactions, which is manifested by an increase in the level of anxiety, a decrease in motor and exploratory activity, and the development of depressive-like states. In the group of a single vibroacoustic exposure, these indicators are restored to the background values in a day, while in the group of multiple vibroacoustic exposure, they remain changed. Conclusion. The data obtained make it possible to study the long-term effects of vibration and noise on the body of firefighters.