Does Heat-Induced Activation of Mast Cells Contribute to Elevated Temperature-Induced Male Infertility?

The microenvironment of spermatogonial stem cells plays a crucial role in determining their developmental trajectory. Mast cells (MCs) are an important component of this microenvironment and are present along the pathway of sperm production and maturation. Elevated temperature is associated with various disorders of male fertility and its effect on MCs has not been previously studied.

The experiment was conducted on male Wistar rats, which were divided into four groups: intact, control, single, and repeated heat exposure. Morphofunctional and morphometric parameters of MCs were investigated in testes, epididymides, and seminal vesicles. Correlation analysis was performed between MC parameters, ejaculated and epididymal spermatozoa, and testosterone levels.

MCs become activated even after a single heat exposure, manifested by increased degranulation. Repeated exposures lead to an increase in MC numbers in the reproductive organs and an enhancement of their functional activity. Testicular MCs exhibit the highest sensitivity to elevated temperature, followed by epididymal MCs. These findings reveal organ-specific differences in MCs responses, which may be explained by the anatomical location of these organs. Correlation analysis revealed a negative relationship between MC morphofunctional parameters and sperm functional characteristics in epididymis and ejaculate, as well as testosterone levels.

Heat exposure activates MCs in male reproductive organs, and the changes in their morphofunctional parameters support a potential role in heat-related male reproductive impairment that requires further evidence.