Experimental study of the combined effect of benzene exposure and physical load in rats

Introduction. The working process in many industries is often associated not only with chemical exposures but also with heavy physical workload, which can be potent of toxic effects of the former differently.

The purpose of the study was to establish body responses to effects of benzene exposure combined with exercise in an experiment on rats.

Materials and methods. The study was conducted on mature male Wistar rats, ten animals in each of the following groups: “Control”, “Running”, “Benzene exposure”, and “Benzene exposure + running”. Subchronic toxicity was modelled by intragastric administration of benzene thrice a week for 4 weeks in a cumulative dose of 100 mg/kg body weight. Exercise was modelled by means of 10-minute forced running sessions at a speed of 25 m/min 5 times a week for 4 weeks. We then measured post-exposure biochemical and hematological indices and the proportion of different types of cells in imprint smears of rat internal organs. Statistical data analysis was carried out using the Student’s t-test with p<0.05. For mathematical modelling of the combined effect of factors, we applied a Response Surface Method (RSM) with the construction of Loewe isobols on its basis.

Results. Almost no statistically significant changes were registered in the rodents who exercised while statistical ones were sporadic and diagnostically insignificant in most cases. Benzene exposure induced changes in blood indices indicating blood clotting disorders, typical of chronic exposure to benzene, and in the antioxidant system. The impact of running on health effects of benzene exposure was ambiguous but isobolographic analysis showed possible additivity and even synergy, both detrimental to health, in 15.6 % of cases.

Limitations. Extrapolation of the study results to human should be done with caution, since the combined effect has been examined only for subchronic exposure using a single species and sex of laboratory animals.

Conclusion. Additivity proven by a number of indices of toxic effect gives important information for understanding and predicting health effects of exposure to organic pollutants combined with physical activity.

Compliance with ethical standards. This experimental study was approved by the institutional Bioethics Committee of the Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers (protocol No. 2 of January 11, 2024).

Contribution:
Minigalieva I.A. – study conception and design, editing;
Shabardina L.V. – data collection and analysis, draft manuscript preparation;
Ryabova Yu.V. – draft manuscript preparation, editing;
Nikogosyan K.M. – data collection;
Panov V.G. – data analysis;
Sutunkova M.P. – editing, study conception and design;
Sakhautdinova R.R. – data collection and analysis.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interest. The authors declare no conflict of interest.

Acknowledgement. The study had no sponsorship.

Received: April 23, 2024 / Revised: May 21, 2024 / Accepted: June 19, 2024 / Published: January 31, 2025