266 EFFECT OF 2,2′,4,4′-TETRABROMODIPHENYL ETHER ON THE EXPRESSION OF CALBINDIN-d9 k IN THE UTERUS OF IMMATURE RATS

Abstract

Polybrominated diphenyl ethers (PBDEs) are well known as one class of halogenated organic brominated flame retardants. They were found in the air, soil, sediments, humans, wildlife, and fish. To date, a total of 209 PBDE congeners have been reported. Among them, 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) is the dominant congener found in humans and animals. A number of studies suggest that BDE-47 possesses the potential to disrupt endocrine and reproductive function(s) via diverse mechanisms. In addition, BDE-47 has been demonstrated to act as a developmental neurotoxicant. Recently, the toxicokinetic properties of BDE-47 have been investigated in order to elucidate the health risk of BDE-47. Thus, in the present study, we employed immature rats as a developmental model to examine the potential involvement of BDE-47 in the expression of uterine calbindin-d9 k (CaBP-9 k), a novel biomarker for screening endocrine disruptors. Immature rats (n = 3) at post-natal Day 16 were treated with different doses (50, 100, and 200 mg kg^-1 of BW) of BDE-47 consecutively for 3 days and euthanized at 24 h after the last injection. After treatment with this chemical, the effects on uterine weight gain and CaBP-9 k mRNA were examined by uterotrophic and RT-PCR assays, respectively. Treatment with a high dose (200 mg kg^-1 of BW/day) of this chemical resulted in a significant increase in the uterine weight in immature rats, whereas a modest increase was observed with lower doses (50 and 100 mg kg^-1 of BW/day). In addition, treatment with BDE-47 at all doses increased the expression level of CaBP-9 k mRNA compared to control. Taken together, these results demonstrate that BDE-47 exposure resulted in an increase of uterotrophic response and CaBP-9 k mRNA in the uterus of immature rats. A further analysis in a time response of this chemical is required to bring new insight into the adverse effect(s) of BDE-47 during the critical window stage of the developing reproductive system.