The effect of combined exposure to acrylamide and circadian stress on behavioral indicators in rats

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Abstract
Introduction. Disruptions in circadian coordination are accompanied by reduced attention, increased fatigue, and a higher likelihood of metabolic and cardiovascular diseases. At petrochemical plants, workers are exposed to chemical factors that, in themselves, can cause damage to the nervous system and disrupt hormonal and metabolic regulation. The impact of the combined effects of chronic circadian stress on workers in chemical plants is an urgent task for modern occupational health.The study aims to determine the specific effects of the combined exposure to acrylamide and circadian stress on the behavioral and motor functions in rats, as assessed in the elevated plus maze test, the grip strength test, and the motor activity test.Materials and methods. Scientists conducted an experiment on white outbred male Wistar rats weighing 190–200 g and aged 6 weeks, kept under standard vivarium conditions with free access to water and food and under a regulated light regime. The researchers divided the animals into 4 groups. For one month, the rats in the experimental groups received acrylamide and were exposed to circadian stress. Upon completion of the experiment, the authors conducted a behavioral assessment, which included the elevated plus maze test to analyze anxious behavior, a grip strength test to assess muscle strength, and a motor activity test to characterize the level of motor activity.Results. The combined exposure to acrylamide and circadian stress led to a decrease in the motor and exploratory activity of rats, an increase in the time during which the animals froze, and the manifestation of anxious behavior in an elevated cross shaped maze. In animals from this group, the researchers observed a decrease in the distance traveled, the speed of movement, the time spent in a mobile state, and the number of entries into the open sections of the maze. In the "Grip Strength" test, the researchers recorded the maximum peak strength in rats from group II, while no pronounced changes were observed with combined exposure.Limitations. The study was conducted on male Wistar rats, which does not allow assessing sexual dimorphism in the response to combined exposure. The small group size (n=7) limits statistical power in multiple comparisons and increases the variability of the estimates. A single dose of acrylamide and a fixed exposure period were used, which limits the analysis of dose–effect and time–effect relationships, as well as the assessment of the reversibility of the observed effects. The applied model of circadian stress was developed by Salgado Delgado R. et al. is not a classical one, and the presented conclusions are based solely on the evaluation of behavioral test results. The model conditions differ from long term cumulative exposure in real production conditions, so quantitative risk assessments cannot be directly applied to humans without additional research.Conclusion. Against the background of combined exposure to acrylamide and circadian stress in rats, the authors observed more pronounced changes in motor and exploratory activity than in the case of isolated exposure to these factors.Ethics. Protocol of the Bioethics Committee Meeting of the Ufa Research Institute of Occupational Medicine and Human Ecology, No. 01-02, dated February 8, 2024. Throughout the study, animals were maintained under standard conditions with twelve hours of artificial lighting during the day, a humidity level of 30–70%, and an air temperature of 20–25°C. For groups II and IV, circadian stress was modeled by daily forced activity during daylight hours, which led to a disruption of the animals' usual daily routine. Animal manipulations were carried out in full compliance with regulatory documents, including the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes (Strasbourg, 1986).Contributions:Gizatullina A.A. — data collection and processing, writing the article text;Yakupova T.G. — participation in conducting experiments, data collection and processing;Khmel A.O. — participation in conducting experiments;Smolyankin D.A. — participation in conducting experiments;Karimov D.D. — data collection and processing;Mukhammadieva G.F. — data collection and processing;Karimov D.O. — development of the concept and study design, statistical data processing;Ziatdinova M.M. — text editing, literature analysis.Funding. The industry specific research program of Rospotrebnadzor for 2021–2025 "Scientific substantiation of the national system for ensuring sanitary and epidemiological well being, managing health risks, and improving the quality of life of the population of Russia", topic 6.9.1.2 "Study of the impact of chemical occupational factors under conditions of chronic stress", No. NIOCTR I124021200153–3.Conflict of interest. The authors declare no conflict of interest.Received: 12.08.2026 / Accepted: 08.10.2026 / Published: 03.11.2026

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