Platform Session 4. Effects of the Environment and Nutrition on Male Reproduction
Sunday, July 24, 2005
3:00 PM–5:00 PM
Location: CCQ 206A
(29) EFFECTS OF THYROID HORMONES ON DI(N-BUTYL) PHTHALATE (DBP)-INDUCED OXIDATIVE DAMAGES IN SPRAGUE-DAWLEY RATS TESTIS.
Lee, Ena 1, Ahn, Mi Young1, Kim, Hee Jin1, Kim, Hyung Sik, 1 Pusan National University, College of Pharmacy, Pusan, Korea
ABSTRACT- Hypometabolitic state induced by hypothyroidism is associated with a decrease in free radical production and in oxidative damage levels. However, it is not clear whether hypothyroidism is associated with decrease in oxidative damage in the testis. This study examined the effects of di(n-butyl) phthalate (DBP) on oxidative damages and antioxidant enzymes activities in the testes of normal and hypothyroid rats. Hypothyroidism was induced in Sprague-Dawley pubertal male rats (4 weeks of age) by administering 0.1% propylthiouracil (PTU) in their drinking water for 30 days. DBP was administered to the hypothyroid (250, 500 or 750 mg/kg) and normal (750 mg/kg) rats by oral gavages for 30 days. The body weight of the PTU-treated hypothyroid rats was significantly lower than the control group. No significant changes in the testis, epididymides and adrenal weight were observed in the hypothyroid rats. However, DBP (750 mg/kg) significantly reduced the weights of the testis in both the normal and hypothyroid rats. The total T3 and T4 serum level decreased, but the TSH level increased in the hypothyroid rats. In contrast, the serum thyroid hormone levels (T3, T4, and TSH) did not change following DBP treatment. Histomorphological examinations showed severe diffused Leydig cells hyperplasias in the DBP (750 mg/kg)-treated groups, but these effects were mild in the DBP-treated hypothyroid rats. The levels of 8-OHdG and MDA were slightly increased in hypothyroid rats, but there was no significant differences were observed in DBP-treated hypothyroid and normal rats. However, glutathione peroxidase (GPx) and catalase (CAT) activities decreased in the testes of hypothyroid rats. These results suggest that hypothyroidism may cause changes in metabolism of DBP and it may cause the protection of testes damages against mono-butyl phthalate (MBP), a primary metabolite of DBP.
KEY WORDS: hypothyroidism, di(n-butyl)phthalate, oxidative damages, thyroid hormones