Protective effect of Shilajit against Bisphenol A-induced pulmonary histopathological alterations in male mice

Abstract

Bisphenol A (BPA) is a pervasive industrial environmental pollutant widely used in chemical manufacturing, leading to continuous human and animal exposure through food and resource contamination. While its broad multi-organ toxicities are well-documented, its sub-acute destructive impact on mammalian respiratory histology requires comprehensive elucidation. Conversely, Shilajit is a traditional mineral pitch known for its potent organic constituents. This study evaluated the lung tissue alterations induced by sub-acute oral BPA exposure and investigated the potential protective efficacy of concurrent Shilajit administration in a male mouse model. Thirty healthy adult male mice were randomly assigned to three equal cohorts: vehicle control (G1), toxic exposure group receiving BPA at 400 mg/kg body weight (G2), and co-treatment group receiving BPA concurrently with Shilajit at 0.5 g/kg body weight (G3) via oral gavage for 21 consecutive days. Following euthanasia, longitudinal lung tissue samples were promptly fixed in 10 % neutral buffered formalin for 48 hours, embedded in paraffin blocks, sectioned, and stained with hematoxylin and eosin (H&E). Stained specimens were subjected to qualitative screening and quantitative scoring. Data were statistically evaluated using Kruskal-Wallis, Dunn’s post hoc, and Fisher’s exact tests. Microscopic evaluation revealed extensive, severe structural damage in 90 % of the BPA-alone group (G2), characterized by diffuse interalveolar septal thickening driven by heavy mononuclear cell (MNC) infiltration, dense accumulation of amorphous proteinaceous exudates within the respiratory spaces, perivascular leukocytic aggregation, and focal alveolar wall rupture driving emphysematous alterations. Conversely, concurrent Shilajit administration (G3) significantly mitigated these changes (P<0.05), successfully restoring normal lung histoarchitecture in 70 % of the cohort. The protected parenchyma demonstrated well-preserved alveolar matrices with mild congestion and localized, contained MNC infiltration. Notably, the G3 group uniquely exhibited distinct interstitial granulomatous accumulations and spherical micro-cavities within the microvascular beds, indicating active tissue regeneration.