Proteolytic system parameters in the brain of rats with hyperhomocysteinemia

Abstract

Hyperhomocysteinemia (HHcy) is now being actively studied as a potential risk factor and/or biomarker for numerous pathological conditions, including brain diseases. This study aimed to analyze the proteolytic processes in the brains of rats with HHcy. Total proteolytic activity, metal-dependent, and serine proteases activities, the content of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases-1, cytokines, serine proteases, total protein and medium and low molecular-weight substances (MLMWS), were evaluated. HHcy was induced by DL-homocysteine thiolactone (HTL) daily intragastric administration (200 mg·kg–1 of body weight) to young and adult albino non-linear male rats for 8 weeks following rat sacrifice and brain harvesting. It was established that HHcy causes an increase in total proteolytic activity and a rise in MLMWS levels in rat brains. Serine protease activity increased to a greater extent compared to metal-dependent one, and bigger changes were observed in young rats. Rise in MMP-9 and -10 levels (in young animals), a decline in MMP-3 and -8 levels, and a decrease in the content of interleukin-1β, interferon-γ, interleukin-4 and tumor necrosis factor-α (the last two in young animals) was also detected. No significant changes were found in serine protease content. Therefore, proteolysis intensification in the brain of rats with HHcy is more likely caused by protease up-regulation through mechanisms stimulated by homocysteine, HTL, and oxidative stress, without involving pro-inflammatory signaling pathways.