Calbindin-D9k mRNA Expression in the Rat Uterus Following Exposure to Methoxychlor: A Comparison of Oral and Subcutaneous Exposure

Abstract

Abstract. Calbindin-D9k (CaBP-9k) is a cytosolic calcium-binding protein that is induced by estrogenic compounds possibly through estrogen receptors. We compared CaBP-9k mRNA expression in the uterus with uterotrophic response in immature rats exposed to methoxychlor (MC), an environmental chemical with estrogenic activity. MC was orally or subcutaneously administered to 3-week-old female Sprague-Dawley rats for 3 days. The weights of the uterus and vagina significantly increased in the oral treatment group at a dose of 50, 100 and 200 mg/kg, but those of the subcutaneous (SC) treatment group only increased at 200 mg/kg. Northern blot analysis showed that CaBP-9k mRNA expression was significantly induced in a dose-dependent manner at doses of 50, 100 and 200 mg/kg/ day in the oral treatment group. SC administration of MC induced significant expression at only a dose of 200 mg/kg/day; this was similar to the uterotrophic response. MC has an estrogenic effect on the uterus as shown by the increase in weight and induction of CaBP-9k mRNA expression, which were much greater following exposure via oral gavage than via the SC route. The strong correlation between the results of in vivo uterotrophic assay and CaBP-9k mRNA expression suggests that CaBP9k mRNA expression in the rat uterus may be used as an early gene marker for detection of the estrogenic effects of putative environmental chemicals.

Calbindin-D9k as a sensitive molecular biomarker for evaluating the synergistic impact of estrogenic chemicals on GH3 rat pituitary cells

“…The gene that we used to measure the effects of EDCs in the present study, encoding the cytosolic calcium-binding protein, calbindin-D9k (CaBP-9k), has been extensively utilized for detecting estrogenic compounds in vitro and in vivo (23). CaBP-9k expression is rapidly and highly induced by estrogenic compounds (e.g., parabens, BPA, OP, NP, phthalates, methoxychlor, diethylstilbestrol and genistein) both in vivo and in vitro, possibly through an ER-mediated pathway (24)(25)(26)(27)(28)(29).…”

Treatment with bisphenol A and methoxychlor results in the growth of human breast cancer cells and alteration of the expression of cell cycle-related genes, cyclin D1 and p21, via an estrogen receptor-dependent signaling pathway

“…In addition, there are in vitro and in vivo data which demonstrates that BPA promotes prostate cancer growth in cells harboring an androgen receptor mutation (34). Recent studies have demonstrated that the estrogenic activity of MXC provides evidence for EDC action in many tissues including the uterus, vagina, brain and bone (35). MXC can bind to ERα and ERβ, which suggest that MXC may be associated with E2-mediated responses in humans (36).…”

Biomarker Genes for Detecting Estrogenic Activity of Endocrine Disruptors via Estrogen Receptors

“…OP, NP, and BPA (600 mg/kg) induce uterine CaBP-9k expression at in the rat; however, lower concentrations (100 to 250 mg/kg) of these compounds had a more prominent effect in mice [84]. Methoxychlor (250 mg/kg) was reported to have a moderate effect on CaBP-9k expression in rat uterus [97]. Butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCHP), 2-ethylhexyl phthalate (DEHP), di- n -butyl phthalate (DBP), and diethyl phthalate (DEP) do not have any significant estrogenic effects on CaBP-9k gene expression in rat uterus [92].…”