THE EFFECTS OF CHEMICAL EXPOSURES ON DNA METHYLATION AND SPERMATOGENESIS

摘要

DNA methylation can be affected by chemical exposure. To investigate the effects of neonatal exposure of 5-Aza-CdR, PCB 153 and Cadmium (Cd) on DNA methylation and spermatogenesis,neonatal SD rats were received oral administrations of 5-Aza-CdR(0.025,0.25mg/kg), PCB153(0.025, 0. 25, 2.5mg/kg)and Cd (1, 2, and 4mg/kg) or vehicle control for five days from PND3. Half of the rats were killed 24h after the last administration. The remains were fed until 11 weeks. TUNEL was used for apoptosis detection and immunofluorescence was applied to measure the level of global DNA methylation in testis. The daily sperm production (DSP) was significantly decreased in neonatal exposed groups (P<0.05) by exposure to 5-Aza-CdR, Cd and PCB153. Neonatal exposure to 5-Aza-CdR and Cd reduced the global DNA methylation level, increased apoptosis, while PCB153 exposure did not significantly change DNA methylation and apoptosis. The results suggested that chemicals could reduce spermatogenesis via multiple pathways and alteration of DNA methylation can be as one of the causes.