RESUMEN
<p><b>OBJECTIVE</b>To investigate the effects of neonatal exposure of DNA methylation inhibitor, Cadmium and PCB153 on DNA methylation, apoptosis and spermatogenesis in SD rats.</p><p><b>METHODS</b>Neonatal SD rats were randomly divided into 10 groups and received oral administrations of PCB153 (0.025, 0. 250, 2.500 mg/kg), or Cadmium (1, 2, 4 mg/kg), or positive control 5-Aza-CdR (0.025, 0.250 mg/kg), or vehicle control for five days from PND3. Half of the rats were killed 24 h after the last administration. The remains were fed until 12 weeks. Sperm numbers, apoptosis and DNA methylation levels in testis were investigated.</p><p><b>RESULTS</b>The daily sperm production was significantly decreased in each neonatal exposed group (P < 0.05). Neonatal rats exposed to 5-Aza-CdR and Cadmium reduced the global DNA methylation level, increased apoptosis, while PCB153 exposure did not significantly change DNA methylation and apoptosis.</p><p><b>CONCLUSION</b>Neonatal rats exposed to chemicals could reduce spermatogenesis via multiple pathways. Lower DNA methylation and increased neonatal apoptosis were suggested as one of the causes.</p>