Effect of water‐soluble silicon compound on properties of macrophages in red pulp of rat spleen

Abstract

Macrophages are target cells for prolonged exposure of silicon compounds. Here we verified the response of spleen red pulp macrophages to the influence of silicon compounds‐supplemented drinking water during 2 and 9 months.The spleens of 6 weeks old white male rats were investigated. First group of control animals (n=5), received standardized drinking water ad libitum during 2 months, second group (n=5) ‐ during 9 months. Third experimental group (n=5) got water, supplemented with sodium metasilicate (10 mg/liter silicon); forth experimental group (n=5) ‐ during 9 months. All procedures with animals were performed in accordance with the prevailing guidelines for animals care. The spleens were isolated immediately after decapitation. Paraffin‐embedded sections (5μm) were stained with antibodies against the IBA‐1 and CD68; freeze‐dried cryostat sections (5μm) were investigated with histofluorescence methods of Cross and Falck‐Hillarp for detection of histamine (H), catecholamines (CA) and serotonin (S); the fluorescence intensity of these amines was measured in arbitrary units (mV) in macrophages and their microenvironment using the FMEL‐1A. Images were captured with help of light microscope MIKMED 5 under ×1000 magnification and collected for further morphometric evaluation with SigmaScan Pro 5.0 software. The sizes of macrophages and the intensity of light transmission of the membrane and cytoplasm were measured in arbitrary units (au). Standard error of the mean (SEM) were calculated for all means.After 2 months we found the changes in morphology of IBA‐1‐positive cells: the cell areas were 83.86 ± 2.45 74 μm2 and 74 ± 2.64 μm2 (p <0.05) in control and in experimental group, respectively. The intensity of the light transmission of the membrane were 95.37 ± 0.73 au and 93.02 ± 0.85 au (p<0.05), light transmission intensity of the cytoplasm −130.43 ± 0.07 au and 126.36 ± 1.22 au (p<0.05), respectively.The relative content of H, CA and S (experiment vs control) in macrophages was 0.91, 0.93, 0.91, and in their microenvironment 1.15, 0.23 and 1.12, respectively. After the 9 months the sizes of CD68‐positive cells in rat spleen treated with silicon were approximatelly 1.3 times smaller than those in the control group. The average intensity of light transmission of the cytoplasmatic membrane of macrophages was 146.64 ± 1.52 au and 143.75 ± 1.17 au, the intensity of light transmission of the cytoplasm − 105.72 ± 1.36 au and 111.36 ± 1.05 au for the control and experimental groups, respectively. The relative content of H, CA and S in macrophages was (experiment vs control) 0.63. 0.53 1.42, in their microenvironment 0.61, 0.60, 1.5, respectively.Thus, the macrophages of the red pulp of rat spleen responsed to impact of silicon to drinking water by reducing the size, redistribution of proteins between membrane and cytoplasm, as well as changing of biogenic amines content. The redistribution of macrophage markers IBA‐1, CD68 may indicate a compensatory response to reducing of cell size.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.