[Joint action of phoxim and fenvalerate on spermatogenesis of male rats].

ABSTRACT

OBJECTIVE: To assess the joint toxicity of phoxim (Pho) and fenvalerate (Fen) on the spermatogenesis of male rats and to clarify its mechanism. METHODS: Based on the three administrative levels of factorial analysis (3 x 3) of Pho and Fen, i. e. their half lethal dose (LD50) 1/250 LD50 (5.9, 2.4 mg/kg) and 1/50 LD50 (29.4, 12.0 mg/kg) and the control, 135 adult male SD rats were randomly assigned to9 groups, the control (0.0 mg/kg), Pho (5.9, 29.4 mg/kg), Fen (2.4, 12.0 mg/kg), Pho + Fen (5.9 + 2.4, 5.9 + 12.0, 29.4 + 2.4, 29.4 + 12.0 mg/kg), and treated intragastrically with different doses of Pho, Fen and Pho + Fen for 15 and 30 days. The levels of serum follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T) and testis homogenate T were determined by radioimmunoassay (RIA), the activity of testicular marker enzymes such as acid phosphatases (ACP) and gamma-glutamyl transpeptidase (gamma-GT) examined, and the sperm head count measured for the changes of daily sperm production (Spr). RESULTS: At 15 days, obvious interaction was observed between Pho and Fen in both serum LH and FSH (P < 0.05), as well as between their reproductive toxicities. With the increase in doses, the joint action was synergistic in LH (P < 0.05) and antagonistic in FSH (P < 0.01) at a high dose ( 29.4 + 12.0 mg/kg). At 30 days, marked interaction between Pho and Fen was noted in the content of homogenate T (P < 0.05) , with a joint synergistic effect. At 15 and 30 days, with the increase of doses, both Pho and Fen reduced Spr and the activity of ACP and gamma-GT, but Pho + Fen showed no obvious interaction in them (P > 0.05) , and their joint action was an additive effect. CONCLUSION: Pho and Fen jointly impaired spermatogenesis in a dose- and time-dependent manner. Their joint action exhibited mainly as a synergistic effect, an additive effect and increased toxicity.