[Effects of dibutyl phthalate on sertoli cells of rat testis]

The present study was performed to examine functional and structural impairment of rat sertoli cells following dibutyl phthalate (DBP) exposure.

The 6-week-old healthy male Sprague Dawley rats were randomly divided into 4 groups with 16 animals in each group. DBP dissolved in peanut oil was administered by gavage at doses of 0, 250, 500 and 1 000 mg/kg. After 2-week DBP treatment, half of the rats were sacrificed. The rest were killed following 4-week DBP exposure. Follicle stimulating hormone (FSH) was analysed by radioimmunoassay. The relative expression levels of androgen binding protein (ABP) mRNA and inhibin (INH)alpha mRNA were determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The sertoli cell ultrastructures were observed by using transmission electron microscope (TEM).

FSH levels were increased after 4-week DBP exposure with significance at doses of 250 and 1 000 mg/kg. Sperm head count and daily sperm product were decreased significantly in 500 and 1 000 mg/kg groups. The expression levels of ABP mRNA were 0.89 +/- 0.15, 0.85 +/- 0.23, 0.54 +/- 0.17, 0.52 +/- 0.16 and 0.88 +/- 0.16, 0.61 +/- 0.12, 0.48 +/- 0.15, 0.47 +/- 0.11 for 0, 250, 500 and 1 000 mg/kg after 2- and 4-week DBP treatments respectively with significance at doses of 500 and 1 000 mg/kg (P < 0.01), while the levels of INHalpha mRNA were 0.88 +/- 0.16, 0.61 +/- 0.12, 0.48 +/- 0.15, 0.47 +/- 0.11 and 0.75 +/- 0.19, 0.56 +/- 0.16, 0.53 +/- 0.08, 0.45 +/- 0.10 with significance at all exposure groups (P < 0.01 or P < 0.05). In sertoli cells of rats exposed to 1 000 mg/kg DBP, TEM photos showed more lysosomes in cytoplasm, proliferated and expanded endoplasmic reticulum and nuclei malformation.

Sertoli cell should be one of the major toxic targets. Impairment of spermatogenesis caused by DBP should be partly due to the suppression of ABP and INHalpha biosynthesis.