The Impacts of Workplace Environment on Coal Miners' Emotion and Cognition Depicted in a Mouse Model

Abstract

Most coal mine accidents are caused by the unsafe behavior of employees. Previous studies have shown that there is a significant connection among the working environment, the psychological state of employees, and unsafe behaviors. However, the internal biological mechanism has not been revealed. To explore the physiological and psychological alterations of coal mine workers and the underlying mechanisms that cause unsafe behaviors, the current study established a novel coal mine environment biological simulation (CEBS) model in mice. This model recreated the underground workplace environment facts in coal mines such as temperature, humidity, and noise, and mice were employed to receive these conditioning stresses according to the 8-h work. Animal behavior tests were performed to evaluate the evolution of the mental state including anxiety and depression, as well as the abilities of learning and memory during the 4-week environmental simulation. CEBS mice showed the adaptation process of anxiety from occurrence to stability in the process of environmental simulation, and also suffered from severe depression compared to the control mice. In addition, impaired spatial memory was also implicated in mice after 4-week CEBS. The behavior results of CEBS mice were consistent with the previous psychological investigation of coal workers. In summary, a novel mouse model was established in this study to depict the occurrence of negative emotions and impaired cognition in coal miners by simulating the underground workplace environment, which provided a basis for further exploring the biological mechanism of miners' unsafe behavior.

Keywords: coal mine; cognition; emotion; unsafe behavior; workplace environment.

FIGURE 1

Diagram of the coal mine environment simulator and the overall experimental workflow. The simulation box was used to construct the CEBS model (A,B); the coal ground (C); video screenshot of the modeling process (D); mice were weighed weekly (E). The overall modeling and experimental procedures of this study (F). On modeling days 7, 14, 21, and 28, EPM and OF tests were used to detect anxiety-like behavior. TST and FST were used to detect depression-like behavior on day 28, followed by a 5-day Morris water maze test on the modeling day 29 to detect spatial memory and learning ability. EPM, elevated plus maze; OFT, open field test; FST, forced swimming test; TST, tail suspension test; MWM, Morris water maze. Data are mean ± SEM from n = 6 mice (Control), n = 20 mice (CEBS: Days 1, 7, 14, and 21), and n = 14 mice (CEBS: Day 28) (E).

FIGURE 2

EPM and OF tests showed that the anxiety-like behavior of the CEBS mice had dynamic change. Schematic diagram of EPM (A) and OFT (E). Different groups of EPM test motion trajectory diagrams (B). Time in open arms (C) and entry onto open arm times (D) in the EPM. Different groups of OF test motion trajectory diagram (F). The distance (G) and time (I) in the center area of the EPM test, the total distance (H) in the OFT. Data are presented as mean ± SEM or median (Interquartile range, IQR) from n = 6–8 mice/control group, n = 20 mice/CEBS group (C,D), and n = 7–15 mice/CEBS group (G–I), *P < 0.05, **P < 0.01, and ***P < 0.001.

FIGURE 3

FST and TST showed that the depressive-like behavior of the CEBS mice was obvious. Schematic diagram of FST (A) and TST (D). Time (B) and times (C) of immobility in FST; time (E) and times (F) of immobility in TST. Data are presented as mean ± SEM or median (Interquartile range, IQR) from n = 11–12 mice/group (B,C,E,F), ***P < 0.001.

FIGURE 4

MWM test showed that the spatial memory of CEBS mice was impaired. Quadrant division of MWM (A). The learning ability change was evaluated in the place navigation stage (B). Trajectory diagram of control group and CEBS group in the spatial probe stage (B). Entries onto platform (D), Distance (E) and time (F) in the target quadrant were used to evaluate the spatial memory ability. Data are presented as mean ± SEM or median (Interquartile range, IQR) from n = 6 mice/group (C–F), ns P > 0.05, *P < 0.05.