Ultrastructural organisation of the spleen of old rats in persistent hyperhomocysteinemia

Abstract

Homocysteine (Hz) is a naturally occurring amino acid formed during methionine metabolism, involving numerouscofactors and enzymes. While homocysteine plays a crucial role in keeping the essential amino acid methionine stable in the body, elevated homocysteine levels can have detrimental effects. An increase in the concentration of homocysteine in the blood serum isconsidered an independent marker of risk for cardiovascular diseases and pathologies of the respiratory system. This study aims tostudy ultrastructural organisation in old rats with persistent hyperhomocysteinemia. The experiment involved 22 male white rats aged 24-26 months, divided into control and experimental groups of 11 individuals. To simulate persistent hyperhomocysteinemia, theexperimental group was administered D, L-thiolactone homocysteine hydrochloride at a dose of 200 mg/kg body weight intragastricallyin a 1% starch gel solution once a day for eight weeks. At the end of the experimental period, the animals were humanely removed fromthe experiment by decapitation under thiopental anaesthesia for further analysis. Pieces of spleen 0.5-1 mm were fixed in a 2.5% glutaraldehyde solution on a phosphate buffer pH of 7.2-7.4. Subsequently, they were introduced into an epon-araldite mixtureaccording to the generally accepted technique. Sections were made from the resulting blocks and stained with toluidine blue and Hayat. After precision microscopy of thin sections, ultrathin sections were made, which were contrasted with a 2% solution of uranylacetate and lead citrate. The sections were examined and photographed under an electron microscope PEM125K with a magnificationof 6-20 thousands of times. In the modelling of hyperhomocysteinemia in old rats, the stroma of the organ was characterised by thegrowth of connective tissue elements. Foci of lymphocyte apoptosis was noted in the spleen's white pulp. In the macrophages of thewhite pulp, lysis and fragmentation of nuclei, as well as accumulation of large amounts of residue in the cytoplasm, were observed. Plasma cells were numerous, and some of them showed signs of destruction. In the red pulp of the spleen, due to hemolysis oferythrocytes, the cytoplasm of macrophages was overflowing with hemosiderin and lipofuscin granules. The latter's presence is alsoevidence of active lipid peroxidation processes.