Long-term activation of mast cells as an experimental model for studying their role in the regulation of spermatogenesis

Mast cells are an important component of the immune microenvironment in the male reproductive system, involved in both physiological regulation and pathological processes via secretion of various bioactive substances. Modeling dysregulation through activation or inhibition of mast cells, and studying the impact of this disturbance on spermatogenesis, may help identify the precise regulatory mechanisms by which these cells influence this process. Ciprofloxacin, an antibiotic known to activate mast cells, has shown efficiency in cardiac mast cell studies but has not been investigated in spermatogenesis. The aim of this study was to evaluate the effects of various ciprofloxacin regimens on mast cells in reproductive organs of male Wistar rats and to determine an optimal dose and duration for developing a model suitable for investigating mast cell involvement in spermatogenesis. Male Wistar rats were treated with ciprofloxacin at 200 and 400 mg/kg for different durations. Morphological and functional characteristics of mast cells in the testes and epididymides were assessed histologically. Ciprofloxacin was shown to modulate the mast cell activity in a time-, dose-, and tissue- dependent manner. At a dose of 200 mg/kg for 7 days, it caused an increase in mast cell numbers, enhanced synthetic activity, and raised the proportion of cells with mature granules in both organs, while degranulation remained unchanged. This indicates a “preparatory” phase involving mast cell migration to reproductive tissues and granule accumulation. This process was followed by active degranulation after 14 days, associated with return to baseline cell numbers, sustained high synthetic activity, and a predominance of mast cells with mature granules, especially in testes. A higher сiprofloxacin dose (400 mg/kg) promoted acceleration of mast cell activation, leading to earlier degranulation. While functional changes were consistent across both organs, morphometric parameters and granule maturation showed tissue-specific responses. Notably, testicular mast cells displayed minimal morphometric changes, possibly due to the immune-privileged nature of the testes. Based on these findings, a 400 mg/kg dose for 7 days is recommended to induce mast cell activation for spermatogenesis studies. A 200 mg/kg сiprofloxacin dose is more suitable for pre-stimulation prior to the use of a degranulation inducer and for long-term studies, in order to minimize possible side effects associated with higher doses.