Transgenerational impairment of ovarian induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) associated with Igf2 and H19 in adult female rat

Abstract

2,3,7,8-Tetrachlorobenze-p-dioxin (TCDD), one of representive Endocrine Disrupting Chemicals (EDCs), has potential adverse effects on human health. Direct exposure to TCDD has been implicated in ovarian follicles development and functions deficits in adulthood. However, it is rarely reported whether indirect exposure to TCDD can cause similar negative impact on F3. The aim of our study was to evaluate the effect of ancestral TCDD exposure on ovarian toxicity in offspring rats (F3), focusing on the Igf2/H19 pathway which was important for follicular development. Pregnant Sprague-Dawley female rats (F0) were given with either vehicle or TCDD (100 or 500 ng/kg BW/day) by gavages during days 8-14 of gestation. Ovarian development and functions of F3 generation was assessed using the ovary coefficient, the vaginal opening time, and regularity of estrous cycle, ovarian pathology, follicles counts and apoptosis of granular cells. The level of E2, FSH and LH in the serum was also detected. Results showed that in the F3 generation 500 ng/kg BW/day TCDD group, ovarian coefficient, LH concentration in serum and number of primary follicles were decreased, and the apoptosis of granular cells was significantly increased. The abnormal rate of estrous cycle and advance rate of vaginal opening time displayed a significantly increase in TCDD-treated groups. RT-PCR analysis showed that the expression level of H19 mRNA in ovary of TCDD treated F3 female rats was increased, compared to the control. Our data showed that ancestral TCDD exposure may impair transgenerational adult ovary development and functions, which may be related to an inhibition of the Igf2/H19 pathway in the ovarian.

Keywords: 2,3,7,8-Tetrachlorodibenzo-p-dioxin; H19; Igf2; Ovarian impairment; Transgeneration.