Response of mast cells in different liver zones under conditions of simulated physical exercise

Background. Tissue myeloid cells occupy a unique position among immune response cells and form cooperative connections with the nervous, endocrine, and immune systems. The liver, being a central metabolic organ, is actively involved in adaptive processes during physical exercise; however, the role of mast cells in these processes remains insufficiently studied. Aim. To evaluate the response of mast cells in different liver zones and the levels of IL-6 and TNF-α in blood plasma under conditions of simulated physical exercise of varying intensity. Materials and Methods. Experiments were conducted on male rats (n=32, body weight 240 g) divided into 4 groups: control (n=8), light exercise (n=8), moderate exercise (n=8), and heavy exercise (n=8). Physical exercise was modeled by forced swimming in a water bath at 29–32°C for 15, 30, and until exhaustion (55–59 minutes), respectively. A total of 10 exercise sessions were performed. Liver samples were fixed in 10% neutral formalin, paraffin sections were prepared and stained with hematoxylin and eosin, as well as toluidine blue to detect mast cells. The distribution density of mast cells, mast cell degranulation index (MCDI), and cell area were determined. TNF-α and IL-6 levels in blood plasma were measured by ELISA. Results. Light exercise did not cause statistically significant changes in mast cell parameters or cytokine levels. Moderate exercise increased the number of mast cells by 1.6-fold, decreased the density of compact forms by 1.1-fold, and increased MCDI by 1.4-fold. Heavy exercise increased the number of mast cells by 2.8-fold, decreased the proportion of compact forms by 1.2-fold, increased MCDI by 1.9-fold, and increased cell area by 1.6-fold (p<0.05). In blood plasma after heavy exercise, TNF-α levels increased by 4.4-fold and IL-6 by 2.6-fold (p<0.001). Histologically, degenerative changes in hepatocytes and inflammatory cellular infiltrates were detected. Strong correlations were found between TNF-α, IL-6, and MCDI (r=0.9, p<0.05), and between TNF-α, IL-6, and mast cell levels (r=0.8, p<0.05). Conclusion. Hepatic mast cells participate in the development of inflammatory responses during intense physical exercise, manifested by increased numbers, activation of degranulation, and correlation with elevated levels of proinflammatory cytokines in blood.