[Single and combined toxic effects of di-2-ethylhexyl phthalate and cypermethrin on fertility and development in the the prepubertal male rats].

OBJECTIVE

To investigate the separate and combined toxic effects of di-2-ethylhexylphthalate (DEHP) and cypermethrin (CYP) on prepubertal male rats.

METHODS

A total of 24 healthy 3-week-old SPF male Sprague-Dawley rats were randomly divided into four groups. They were control group (fed with corn oil), DEHP group (500 mg/kg, dissolved in corn oil), CYP group (80 mg/kg, dissolved in corn oil), combine group (DEHP 500 mg/kg + CYP 80 mg/kg, dissolved in corn oil), respectively. Each group consists of 6 rats. All the rats were exposed to DEHP or CYP by the means of gavage administration, once a day for 30 days. They were executed 24 hours after the last administration, and their weight, wet weight of the testis and testis coefficient was calculated. The histomorphological examination of the testis was conducted and the serum testosterone level was measured by Radioimmunoassay. The activities of LDH, ACP, ALP and SDH were assessed in testis homogenate.

RESULTS

Compared with control group, the time of testicular descent and preputial separation was significantly delayed and the anogenital distance was significantly shorter in DEHP group, CYP group and combine group (P < 0.05 or 0.01). In DEHP group, the wet weight of testis, testis coefficient and the serum level of testosterone were significantly decreased (P < 0.05). The activity of ALP, ACP and LDH in testis homogenate was significantly increased, but that of SDH was significantly decreased (P < 0.01). Histologic structure and ultrastructure of testis showed obvious abnormalities in DEHP group, CYP group and combine group.

CONCLUSIONS

DEHP and CYP had obviously separate and combined reproductive toxicity to prepubertal male rats. Both of them could cause the degeneration, necrosis and dysfunction of the seminiferous epithelium, sertoli cells and leydig cells and resulted in the abnormal development and function of the male reproductive system. Rats exposed to DEHP alone showed main toxic effect. There was no interactive influence on reproductive toxicity between DEHP and CYP in the combine group.