chronic scrotal heat stress causes testicular interstitial inflammation and fibrosis: an experimental study in mice

Background: chronic heat stress is a risk factor that adversely affects the reproduction system. inflammation and fibrosis are 2 important response processes to damaged tissues. objective: this study investigates the association of chronic scrotal heat stress with testicular interstitial inflammation and fibrosis in mice. materials and methods: for all experiments, 8-10 wk old male swiss mice (mus musculus) (20-23 gr) were divided into 3 groups (n = 10/each). the heat-stress groups were submerged in a water bath at 37°c and 40°c, while the control group was treated at 25°c. the testicular tissues underwent hematoxylin and eosin staining, picro sirius red staining, and immunohistochemistry for intercellular adhesion molecule-1, fibroblast-specific protein 1, f4/80, collagen i, and ki-67 staining to determine the testicular interstitial inflammation and fibrosis. results: chronic scrotal heat stress impairs spermatogenesis and reverses testicular histological structure. in this study, heat stress significantly induced increased interstitial cell proliferation and upregulation of intercellular adhesion molecule-1 expression in the interstitial testicular tissue. in the interstitial testicular tissue, the number of f4/80-positive macrophages and the number of fibroblast-specific protein 1- positive fibroblasts were significantly increased in the heat-exposed groups compared to those in the control group. the heat exposed groups had substantially increased extracellular matrix collagen accumulation in their testicular interstitial tissues. conclusion: heat stress adversely affects the testicular structure and spermatogenesis, causes inflammation, and leads to testicular interstitial fibrosis.