Germ cell apoptosis in rat testis after administration of 1,3-dinitrobenzene

The present study investigated the occurrence of apoptosis in rat testis 6, 12, 24, or 48 h after administration of 1,3-dinitrobenzene (DNB)(25 mg/kg, i.p.). Apoptotic cells were visualized using TUNEL in situ detection. In untreated control animals, occasional tubules contained a few apoptotic nuclei. After DNB treatment, more tubules were apoptotic and more germ cells within individual tubules were affected. The increase in incidence and severity of apoptosis was statistically significant 24 and 48 h after exposure. Spermatocytes were the primary cell population affected. Apoptosis was primarily present in Stages VI-VIII and IX-XIII. DNA ladders, characteristic of apoptosis, were clearly present by 24 h after DNB administration, faint at 12 h, and not present in the control or at 6 h. Although initiating mechanisms may be very different for different chemicals, apoptosis is a common and late manifestation of the testicular response to numerous toxicants.