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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. [ABSTRACT FROM AUTHOR]

Objective. Various phenomena guarantee gamete maturation and formation at all stages of evolution, one of which is autophagy playing a critical role in the final morphology of gametes, particularly sperms. Autophagy is influenced by oxidative stress, disturbances of calcium homeostasis, and hyperthermia conditions. The current study aimed to assess the autophagy-related proteins along with the activity of sperm calcium channel (CatSper) proteins following the induction of heat stress (HS). Methods. The study sample includes two groups of adult mice: sham and HS groups. In the HS group, the right testis was transferred to the abdominal cavity for 120 hours and then returned to the scrotum where it remained for 7 days. After 7 days, the testis and epididymis were removed to conduct real-time, immunohistochemical studies, sperm parameter evaluation, and seminiferous tubule assessment. In this study, the expression and distribution of autophagy proteins were measured. Plus, CatSper1 and CatSper2 were evaluated as proteins of calcium channels. Results. The results of the present study demonstrated that the expression intensity of autophagy indices in seminiferous tubules decreased significantly after HS induction, which was associated with a decrease in the distribution of CatSper proteins in the sperms. HS led to morphological changes in sperm, reduced motility and viability of sperm, and decreased spermatogenesis indices. Conclusion. In this study, following heat stress, the decrease in CatSper protein distribution may lead to the structural disorder of CatSper channels, which could strongly affect autophagic activity. Also, disruption of spermatogenesis and sperm parameters may be the consequence of decreased autophagy activity. [ABSTRACT FROM AUTHOR]