Single administration of butylparaben induces spermatogenic cell apoptosis in prepubertal rats

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. Some parabens, including butylparaben, exert an estrogenic activity as determined by in vitro estrogen receptor assay and in vivo uterotrophic assay, and adversely affect endocrine secretion and male reproductive function. We conducted a research study to evaluate the acute effects of butylparaben on testicular tissues of prepubertal rats. Three-week-old male rats (n=8) were given a single dose of 1000mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration, and their testes were collected for histopathological examination. The study revealed progressive detachment and sloughing of spermatogenic cells into the lumen of the seminiferous tubules at 3h, and this effect was enhanced at 6h after administration. Thin seminiferous epithelia and wide tubular lumina were seen at 24h in the butylparaben-treated group, compared to the control. In order to clarify whether sloughed spermatogenic cells underwent apoptosis, TUNEL assay was carried out. We found a significant increase in the number of apoptotic spermatogenic cells in all the treated groups, compared to the controls and a maximal number of apoptotic cells were detected at 6h after administration. In semithin sections, apoptotic cells were easily detected by their prominent basophilia and condensed chromatin, mainly found in spermatocytes. Ultrastructurally, the condensed chromatin and shrunken cytoplasm and nucleus, hallmarks of apoptotic cell death, were observed in butylparaben-treated groups. These observations lead us to postulate that butylparaben, similar to other estrogenic compounds, also induces spermatogenic cell apoptosis.