Histological changes in the dentate gyrus of the hippocampus in rats with induced colon adenocarcinoma and after correction with nanomaterials

The hippocampus plays a significant role in the formation of multiple central nervous system functions and is highly sensitive to pathological influences, as demonstrated in numerous experimental studies. However, the impact of induced colorectal adenocarcinoma on the structural organization of the hippocampus remains unclear. Therefore, the aim of our study was to investigate histological changes in the dentate gyrus under conditions of N,N-dimethylhydrazine (DMH)-induced colon cancer in rats, as well as to evaluate the corrective effects of Au/Ag/Fe nanomaterials. A total of 45 white rats were used and divided into three groups: Group I – intact rats, Group II – rats with DMH-induced oncogenesis, Group III – rats with DMH-induced adenocarcinoma receiving a composition of Au/Ag/Fe nanomaterials. Carcinogenesis was induced by subcutaneous administration of N,N-dimethylhydrazine (DMH, batch D161608, Sigma-Aldrich Sp. z o.o., Japan) once weekly for 30 weeks in the interscapular region. The composition of Au/Ag/Fe nanomaterials was administered intragastrically once daily for 21 days to rats of Group III. Brain samples were processed according to standard histological protocols, and sections were stained with toluidine blue and hematoxylin-eosin. Morphological changes were visualized using a MICROmed SEO SCAN microscope equipped with a Vision CCD camera. Histological examination revealed that rats of Group II demonstrated the most pronounced alterations in the granular layer of the dentate gyrus, including decreased cell density, presence of activated glial cells and shadow cells, nuclear pyknosis, and disrupted ratios of normochromic to hyper- and hypochromic neurons. Hemodynamic disturbances with the development of stasis, sludge, and perivascular edema were also observed. Administration of the Au/Ag/Fe nanocomposite contributed to restoration of the structural organization of the granular layer, with increased cell density, reduction of glial elements, and normalization of hippocampal stratification. Correction with nanomaterials substantially improved the morphological state of the hippocampus, reduced the severity of pathological alterations, promoted restoration of the cellular architecture of the dentate gyrus, and normalized the condition of the microvascular network.