Effects of peat smoke exposure during the early postnatal period on behavior and electroencephalogram in adult rats

Introduction. Exposure to smoke from natural peat fires during the early postnatal period leads to the development of a wide range of pathological conditions, among which the long-term effects of smoke on the central nervous system (CNS) remain the least studied.

Materials and methods. Inhalation exposure of newborn rats to peat smoke was carried out during critical periods of ontogenesis – from the 23^rd to the 27^th day of life. The CO concentration in the inhalation chambers was 21 (13; 28) mg/m³, and the PM_2.5 concentration was 0.09 (0.04; 0.19) mg/m³. At 3 months of age, the functional state of the CNS was assessed in the rats. The examination included open field behavioral testing, EEG recording, and histological examination of the cerebral cortex.

Results. Males exhibited a sharp reduction in time spent in the center of the arena and a decrease in the exploratory area, indicating suppression of the active-searching component of behavior. EEG results in males showed a decrease in EEG amplitude characteristics, primarily due to waves in the low-frequency range (delta and theta rhythms). In females, conversely, an increase in amplitude and index was observed, largely due to fast-wave beta rhythm activity. No changes in nervous tissue structure were detected.

Limitations. This study is limited to adult sexually mature white rats exposed to peat smoke from 23^rd to 27^th postnatal day.

Conclusion. Exposure to peat smoke in the early postnatal period leads to impairments in species-specific behavior and the amplitude-frequency properties of the total bioelectrical activity of the cerebral cortex in adult sexually mature rats. The most significant shifts in CNS impairment are observed in male white rats.

Compliance with ethical standards. The study was approved by the Local Ethics Committee of the East-Siberian Institute of Medical and Ecological Research (Protocol No. 32 dated 01/10/2023) and was conducted in accordance with the European Convention for the Protection of Vertebrate Animals used for Experimental and Other Scientific Purposes (ETS No. 123) and Directive 2010/63/EU of the European Parliament and of the Council of the European Union of September 22, 2010 on the protection of animals used for scientific purposes.

Contributions:
Sosedova L.M. – study concept and design, literature review, manuscript writing;
Vokina V.A. – study concept and design, experiment conduction, data processing, analysis and interpretation, literature review, manuscript writing;
Pankova A.A. – experiment conduction, data collection and primary processing, statistical analysis;
Titov E.A. – histological specimen preparation and processing, data processing, statistical analysis;
Novikov M.A. – histological specimen preparation and processing, data processing, statistical analysis;
Savchenkov M.F. – editing, approval of the final version of the manuscript, responsibility for the integrity of all parts of the manuscript.

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

Funding. The study had no sponsorship.

Received: March 24, 2026 / Revised: May 18, 2026 / Accepted: June 18, 2026 / Published: July 31, 2026

1. Schultz E.S., Hallberg J., Bellander T., Bergström A., Bottai M., Chiesa F., et al. Early-life exposure to traffic-related air pollution and lung function in adolescence. Am. J. Respir. Crit. Care Med. 2016; 193(2): 171–7. https://doi.org/10.1164/rccm.201505-0928OC https://elibrary.ru/ywshfd

2. Künzli N., Avol E., Wu J., Gauderman W.J., Rappaport E., Millstein J., et al. Health effects of the 2003 Southern California wildfires on children. Am. J. Respir. Crit. Care Med. 2006; 174(11): 1221–8. https://doi.org/10.1164/rccm.200604-519OC

3. Reid C.E., Maestas M.M. Wildfire smoke exposure under climate change: impact on respiratory health of affected communities. Curr. Opin. Pulm. Med. 2019; 25(2): 179–87. https://doi.org/10.1097/MCP.0000000000000552

4. Rebuli M.E., Speen A.M., Martin E.M., Addo K.A., Pawlak E.A., Glista-Baker E., et al. Wood smoke exposure alters human inflammatory responses to viral infection in a sex-specific manner. A randomized, placebo-controlled study. Am. J. Respir. Crit. Care Med. 2019; 199(8): 996–1007. https://doi.org/10.1164/rccm.201807-1287OC

5. Burbank A.J., Sood A.K., Kesic M.J., Peden D.B., Hernandez M.L. Environmental determinants of allergy and asthma in early life. J. Allergy Clin. Immunol. 2017; 140(1): 1–12. https://doi.org/10.1016/j.jaci.2017.05.010 https://elibrary.ru/yiunqc

6. Efimova N.V., Abramatets E.A., Tikhonova I.V. The impact of the chemical factor on children’s health with account of the early stages of ontogenesis. Gigiena i Sanitaria (Hygiene and Sanitation, Russian journal). 2014; 93(6): 83–6. https://elibrary.ru/tfaoal (in Russian)

7. Vokina V.A., Andreeva E.S., Novikov M.A., Sosedova L.M. A device for simulating intoxication in small laboratory animals by biomass combustion products. Patent RF № 213283 U1; 2022. https://elibrary.ru/rvksgf (in Russian)

8. On the sanitary and epidemiological state of the territories of the Russian Federation affected by the fire and the measures taken by Rospotrebnadzor as of August 9, 2010. Available at: https://37.rospotrebnadzor.ru/document/1190/ (in Russian)

9. Kulikov A.V., Tikhonova M.A., Kulikov V.A. Automated measurement of special preference in the open field test with transmitted lighting. J. Neurosci. Meth. 2008; 170(2): 345–51. https://doi.org/10.1016/j.jneumeth.2008.01.024 https://elibrary.ru/lljlzh

10. Liu J.C., Peng R.D. The impact of wildfire smoke on compositions of fine particulate matter by ecoregion in the Western US. J. Expo Sci. Environ. Epidemiol. 2019; 29(6): 765–76. https://doi.org/10.1038/s41370-018-0064-7 https://elibrary.ru/oivrwn

11. Lelieveld J., Pozzer A., Pöschl U., Fnais M., Haines A., Münzel T. Loss of life expectancy from air pollution compared to other risk factors: a worldwide perspective. Cardiovasc. Res. 2020; 116(11): 1910–7. https://doi.org/10.1093/cvr/cvaa025 https://elibrary.ru/wokkfk

12. De Florio-Barker S., Crooks J., Reyes J., Rappold A.G. Cardiopulmonary effects of fine particulate matter exposure among older adults, during wildfire and non-wildfire periods, in the United States 2008–2010. Environ. Health Perspect. 2019; 127(3): 37006. https://doi.org/10.1289/EHP3860

13. Haikerwal A., Akram M., Del Monaco A., Smith K., Sim M.R., Meyer M., et al. Impact of fine particulate matter (PM2.5) exposure during wildfires on cardiovascular health outcomes. J. Am. Heart. Assoc. 2015; 4(7): e001653. https://doi.org/10.1161/JAHA.114.001653

14. Wright R.J., Brunst K.J. Programming of respiratory health in childhood: influence of outdoor air pollution. Curr. Opin. Pediatr. 2013; 25(2): 232–9. https://doi.org/10.1097/MOP.0b013e32835e78cc

15. Mahmudova N.Sh. EEG of visual and sensorimotor cerebral cortex of the infant rats of early age who transferred influence of a hypokinesia to the germinal period of prenatal development. Mezhdunarodnyi nauchno-issledovatel’skii zhurnal. 2016; (3–3): 23–8. https://doi.org/10.18454/IRJ.2016.45.072 https://elibrary.ru/vowxtf (in Russian)

16. Zapadnyuk I.P., Zapadnyuk V.I., Zakhariya E.A., Zapadnyuk B.V. Laboratory Animals. Breeding, Maintenance, and Use in Experiments [Laboratornye zhivotnye. Razvedenie, soderzhanie, ispol’zovanie v eksperimente]. Kiev: Vishcha shkola; 1983. (in Russian)

17. Kassil V.G., Otellin V.A., Khozhaǐ L.I., Kostkin V.B. Critical phases of the brain development. Rossiiskii fiziologicheskii zhurnal im. I.M. Sechenova. 2000; 86(11): 1418–25. https://elibrary.ru/mpewvf (in Russian)

18. Land S.C., Wilson S.M. Redox regulation of lung development and perinatal lung epithelial function. Antioxid. Redox Signal. 2005; 7(1–2): 92–107. https://doi.org/10.1089/ars.2005.7.92

19. Kajekar R. Environmental factors and developmental outcomes in the lung. Pharmacol. Ther. 2007; 114(2): 129–45. https://doi.org/10.1016/j.pharmthera.2007.01.011 https://elibrary.ru/mkptyt

20. Korten I., Ramsey K., Latzin P. Air pollution during pregnancy and lung development in the child. Paediatr. Respir. Rev. 2017; 21: 38–46. https://doi.org/10.1016/j.prrv.2016.08.008

21. Dugershaw B.B., Aengenheister L., Hansen S.S.K., Hougaard K.S., Buerki-Thurnherr T. Recent insights on indirect mechanisms in developmental toxicity of nanomaterials. Part. Fibre Toxicol. 2020; 17(1): 3. https://doi.org/10.1186/s12989-020-00359-x https://elibrary.ru/xykkvj

22. Veras M.M., de Oliveira Alves N., Fajersztajn L., Saldiva P. Before the first breath: prenatal exposures to air pollution and lung development. Cell Tissue Res. 2017; 367(3): 445–55. https://doi.org/10.1007/s00441-016-2509-4 https://elibrary.ru/ssecpq

23. Redina O.E., Smolenskaya S.E., Markel A.L. Genetic control of the behavior of ISIAH rats in the open field test. Russian Journal of Genetics. 2022; 58(7): 791–803. https://doi.org/10.1134/s1022795422070146 https://elibrary.ru/etfjju

24. Apukhtin K.V., Shevlyakov А.D., Kotova М.M., Amikishiev S.V., Riga V.D., Volgin A.D., et al. Analysis of rodent grooming and its microstructure in modern neurobiological studies. J. Evol. Biochem. Phys. 2024; 60(3): 1125–43. https://doi.org/10.1134/S0022093024030219 https://elibrary.ru/oqqhzi