Hypothyroidism protects di(n-butyl) phthalate-induced reproductive organs damage in Sprague-Dawley male rats

This study examined the deleterious effects of di(n-butyl) phthalate (DBP) on the male reproductive organs in hypothyroid rats. Hypothyroidism was induced in prepubertal male rats (28 days of age) by an intraperitonial (i.p.) injection of 10 mg/kg/day propylthiouracil (PTU) for 30 days. DBP (100 and 500 mg/kg/day) was administered by oral gavages to the intact or hypothyroid rats for 30 days. The body weight of the PTU-treated rats was significantly lower than the control group. The total triiodothyronine (T3) and thyroxine (T4) serum level was lower, and the thyroid-stimulating hormone (TSH) level was higher in the hypothyroid rats than in the control rats. The DBP treatment rats showed significantly lower testes, epididymides, seminal vesicles, and ventral prostate weights than the untreated rats. The hypothyroid rats had significantly higher thyroid weights and lower adrenal glands weights than the control rats. The histomorphological examination showed diffused Leydig cells hyperplasias and germ cells loss in the DBP (500 mg/kg)-treated rats, whereas these effects were mild in the DBP-treated hypothyroid rats. The serum levels of monobutyl phthalate (MBP) were significantly lower in PTU-induced hypothyroid rats than in the DBP-treated rats. This data suggests that the hypothyroid status might offer some protection from male reproductive organ toxicity caused by a disturbance in the metabolic activation of the parent compound, DBP.