Experimental modeling of chemical pneumonitis in rats after intragastric administration of gasoline

Introduction. The toxic effect of gasoline is associated with CNS dysfunction and respiratory damage, such as chemical pneumonitis, which contributes to the severity of the condition of patients with acute oral poisoning. Currently, there are no pathogenetically based approaches to the treatment of chemical pneumonitis caused by oral intake of gasoline. Adequate experimental models in animals are necessary for the development of pathogenetic therapy.

The aim of this study was to develop an experimental model of chemical pneumonitis in rats caused by intragastric gasoline administration.

Material and methods. The experimental study was performed on 128 rats. AI-92 gasoline (hereinafter referred to as gasoline) was used as a toxicant, which was administered intragastrically once using a probe at a dose of 10.3 ± 0.44 ml / kg, (n = 6 in the group). At stage 1, the acute toxicity of gasoline was assessed using the Finney probit analysis method, and the mean lethal dose (LD₅₀) was determined. At stage 2, the adequacy of the mathematically selected dose was checked. At stage 3, morphological, histological, and radiological changes in the lungs were studied on days 1, 2, 5, and 14 after intragastric administration of gasoline (LD₅₀).

Results. It was found that the mean lethal dose of gasoline after a single intragastric administration was 10.3±0.44 ml/kg. Lethal outcomes due to direct neurotoxic effects occurred within the first two hours after exposure to gasoline (30 ± 14%), while lethal outcomes due to respiratory failure occurred within the first five days after exposure (60 ± 15%). An increase in the pulmonary coefficient was observed at all observation periods, with the most pronounced increase occurring 24 hours after exposure. The increase in the pulmonary coefficient was accompanied by the appearance of macroscopic changes: the surface of the lungs is cherry-blue in color with multiple subpleural hemorrhages, foamy exudate in the trachea, foci of hemorrhagic impregnation of the lung parenchyma; histological changes: subtotal interstitial edema with a pronounced cellular reaction, swelling and fragmentation of collagen fibers, areas of disatelectasis, destruction of alveolocytes with the formation of detritus and ruptures of the interalveolar septa; radiological changes: increased pulmonary pattern, focal infiltration in the upper segments of the lungs. By day 14 after exposure, histological changes in the lung tissues characteristic of chronic inflammation with moderate lymphoid infiltration, hyalinization of the alveolar membranes and local fibrous changes persisted. These identified changes in the lung tissues were caused by the direct damaging effect of gasoline on the components of the aerogematic barrier, which was associated with its excretion through exhaled air.

Limitations. The study is limited by its methodology. Gasoline blood concentrations were not measured.

Conclusion. A reproducible experimental model of chemical pneumonitis in rats was developed using intragastric gasoline administration (LD₅₀), with disease severity determined by acute respiratory failure.

Compliance with ethical standards. The study was approved by the Independent Ethics Committee of the S.M. Kirov Military Medical Academy (Protocol No. 287 dated January 23, 2024), The study was conducted in accordance with the European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes (ETS N 123) and with the Directive 2010/63/EC of the European Parliament and of the Council of 22 September 2010 on the Protection of Animals Used for Scientific Purposes.

Authors’ contribution:
Smirnov A.N. – concept and design of research, collection of material, writing;
Bugorskiy I.B. – collection of material and data processing, writing;
Blinov A.K. – collection and processing of material;
Smirnova A.E. – collection and processing of material;
Kuzmich V.G. – collection and processing of material;
Tolkach P.G. – responsibility for the integrity of all parts of the article, writing;
Yazenok A.V. – editing, approval of the final version of the article.
All co-authors are responsible for approving the final version of the article and ensuring the integrity of all its parts.

Conflict of interest. The authors declare no apparent and potential conflicts of interest in relation to the publication of this article.

Funding. The study had no sponsorship.

Received: May 10, 2025 / Revised: June 10, 2025 / Accepted: February 2, 2026 / Published: March 18, 2026

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