The Effect of Chrysin on the Distribution of Extracellular Matrix Proteins around Leydig Cells under Heat Stress Injury

Abstract

Objective. In the testicular tissue stroma, matrix proteins such as laminin and fibronectin play a critical role in transmitting signals under normal and stressful conditions to Leydig cells. Heat stress is considered one of the stressful conditions in the testicular tissue. This study has investigated the protective effects of chrysin on the distribution of laminin and fibronectin around Leydig cells under heat stress. Methods. Rats were divided into four groups, including sham (A), heat stress (B), heat stress with chrysin treatment (50 mg/kg) (C), and heat stress with chrysin treatment (75 mg/kg) (D). At the end of the treatment period, on the 21st day, testosterone serum levels were evaluated, and the testes were also assessed to determine the changes in gene expression and distribution of laminin, fibronectin, and caspase-3 proteins. Results. Exposure to heat stress in Group B resulted in increased levels of caspase-3, decreased activity, height, and diameter of seminiferous tubules, and altered distribution of laminin and fibronectin proteins around the Leydig cells when compared to the sham group ($p<0.05$). Treatment with chrysin 75 resulted in a significant decrease in caspase-3 levels, improved testosterone levels, and increased distribution of laminin and fibronectin around Leydig cells compared to group B ($p<0.05$). In addition, the group treated with chrysin 75 showed improved seminiferous histological activity markers in comparison to group B ($p<0.05$). Conclusion. Following heat stress, concurrent with disrupted steroidogenesis, an evident change happens in the distribution pattern of the extracellular matrix (ECM) proteins of the testis, which may indicate the transmission of stress signals from the ECM to the Leydig cells. Treatment of chrysin in 75 mg/kg dose can reduce the damage caused by heat stress on the ECM and Leydig cells.