Effects of daily exposure to peat smoke on the reproductive and nervous systems in male white rats

Introduction. The regular occurrence of large-scale peat fires is an urgent medical and environmental problem of the modern scientific community. The peat smoke is a complex mixture of pollutants that have a serious impact on air quality and public health.

Materials and methods. Adult male rats were exposed to peat smoke for 24 hours, the concentrations of PM_2.5 and CO were 0.92±0.08 mg/m³ and 40.8±1.9 mg/m³, respectively. After exposure an open field examination, EEG examination and histological analysis of the testes and brain were performed, after which they were mated with intact females. Postnatal death of offspring in the first week of life, body weight, behaviour and electroencephalography indicators during puberty were evaluated.

Results. There was showed an increase in motor activity, anxiety, and violation of EEG indicators in rat males exposed to peat smoke. Both an increase in shadow cells and degeneratively altered neurons in the nervous tissue were found. No changes were detected in the testes. Exposure to peat smoke during conception increased stillbirth and mortality of offspring during the first week of life, but did not affect weight gain. Violation of behaviour structure was recorded only in females offspring. An increase in slow-wave activity of the brain in males offspring was revealed.

Limitations. The study was limited to studying the effects of a single 24-hour exposure to peat smoke on outbred white rats.

Conclusion. A single peat smoke exposure for 24 hours at a concentration of PM_2.5=0.92±0.08 mg/m³ and CO=40.8±1.9 mg/m³ leads to significant morphological and functional changes in the CNS. In the absence of a gonadotoxic effect, peat smoke exposure on males before mating causes specific changes in the behavior and bioelectrical activity of the brain of their offspring.

Compliance with ethical standards. The study was approved by the Local Ethics Committee (LEC) of the East Siberian Institute of Medical and Environmental Research (Protocol of the LEC of the No. 32/19 of 09/10/2019), conducted in accordance with the European Convention for the Protection of Vertebrates Used for Experiments or Other Scientific Purposes (ETS N 123), directive of the European Parliament and the Council of the European Union 2010/63/EC of 22.09.2010 on the protection of animals used for scientific purposes.

Contribution:
Vokina V.A. — concept, literature search, experiment, writing, statistical processing, article design,
Sosedova L.M. — concept, literature search, writing, article design, responsibility for the integrity of all parts of the article;
Novikov M.A. — search and translation of literary sources, experiment;
Andreeva E.S. — justification of relevance, literature search, experiment, results processing;
Titov E.A. — morphometric results processing;
Rukavishnikov V.S. — guidance, analytical work, discussion of relevance and results;
Savchenkov M.F. — discussion of relevance and results.
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.

Acknowledgment. The work was carried out according to the research plan within the framework of the state task andsupported by the Ministry of Science and Higher Education of the Russian Federation, the grant No. 075-15-2020-787for implementation of Major scientific projects on priority areas of scientific and technological development (the project «Fundamentals, methods and technologies for digital monitoring and forecasting of the environmental situation on the Baikal natural territory»).

Received: April 11, 2023 / Accepted: June 7, 2023 / Published: August 30, 2023