Objective To investigate the effects of neonatal exposure of 2, 2', 4, 4', 5, 5'-hexachlorobiphenyl (PCB153) on apoptosis both in vivo and in vitro in male SD rats.
Methods In vivo experiments:neonatal SD rats (postnatal day 3, PND 3) were randomly divided into 4 groups and received oral administrations of PCB153 (0.025, 0.250, 2.500 mg/kg)or vehicle control for 5 d. Half of the rats were killed in 24 h after the final administration. The remains were fed until 12 weeks. The histological changes of rat testicular tissue of PND8 rats were examined by electronic microscope. The apoptosis and count of germ cells were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay(TUNEL). The daily sperm production of 12 week adult rats was recorded. In vitro experiments:PCB153 (0, 1, 10 and 50 μmol/L) were exposed to co-culture system for 24 h after germ cells and sertoli cells were co-cultured for 48 h. AnnexinV-fluorescein isothiocyanat (FITC) and propidium iodide was used for detecting early and late apoptosis rate by flow cytometer (FCM); 4', 6-diamidino-2-phenylindole (DAPI)staining was for observing apoptosis in cell nuclei.
Results The daily sperm product in the 0.250 mg/kg and the 2.500 mg/kg dose groups were significantly reduced compared with that of the contro(l P < 0.05). PCB153 was not found to induce apoptosis in the germ cells by TUNEL detection. Electron microscopy revealed mitochondria swelled in the sertoli cells and nucleus pyknosis in the germ cells after 24 h PCB153-treated in vivo. In the 50 μmol/L group, the early apoptosis rate was significantly higher than the control group tested by FCM (P < 0.05). Apoptotic cell nuclei in the 10 μmol/L group were significantly increased compared with the control group.
Conclusion Neonatal rats exposed to PCB153 could induce apoptosis both in vivo and in vitro at certain dosage. The lo ng-term damage to male reproductive function is possibly caused by neonatal exposure to chemicals.
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