[The effects of DEHP on morphology and function of progenitor Leydig cell in rat]

To investigate the effects and mechanisms of diethylhexylphthalate (DEHP) on morphology and function of progenitor Leydig cells (PLC) in rats.

Twenty pregnant SD rats were randomly divided into 4 groups ( n = 5): normal control group, DEHP low dose group , middle dose group, and high dose group, which were treated from postnatal day (PND) 1 to PND 21 of the pubs with DEHP at the doses of 0, 10, 100, 750 mg/(kg · d) in 0.5 ml of corn oil by gavage respectively. At the end of the treatment, the male pups were killed and blood samples were collected for determination of serum testosterone concentration by chemiluminescence method. The body weight, testis weight and anogenital distance (AGD) were measured. The morphology of PLC was observed by light and transmission electron microscopy. The protein expression of steroidogenic acute regulatory protein(StAR) in PLC was determined by immunohistochemistry. The mRNA expression of insulin-like growth factor-I (IGF-I) in the testis was assayed by real-time PCR.

Compared with normal control group, the serum testosterone and AGD of male pubs from the middle and high dose groups were declined significantly (P < 0.01), the testis weight and body weight from high dose group were decreased significantly (P < 0.01), while the testis weight increased in the low dose group (P < 0.05). Under light microscope, PLC showed hyperplasia and cluster aggregation in the low dose group and focal hyperplasia in the middle and high dose group. The spermatogenic cells in seminiferous tubules showed decrease, apoptosis and unfix in the high dose group. Under transmission electron microscope, the PLC showed decreased lipid droplets, smooth endoplasmic reticulum and mitochondriae in the treated group. The mRNA expression of IGF-I increased in the low dose group, and the protein expression of StAR decreased in the middle and high dose group.

Lactating exposure to DEHP may interfere with the synthesis of testosterone of PLC in male pubs, the decrease of StAR and the damage of PLC may be involved in it.