Anti-progestogenic effect of flutamide on uterine expression of calbindin-D9k mRNA and protein in immature mice

• Published in: Reproductive toxicology (Elmsford, N.Y.) N.Y.), 2006-11, Vol.22 (4), p.694-701
• Main Authors: JI, Youn-Kyu, LEE, Geun-Shik, CHOI, Kyung-Chul, JEUNG, Eui-Bae
• Format: Article
• Language: English
• Subjects: Androgen Antagonists - pharmacology; Animals; Biological and medical sciences; Blotting, Northern - methods; Blotting, Western - methods; Calbindins; Dose-Response Relationship, Drug; Embryology: invertebrates and vertebrates. Teratology; Female; Flutamide - analogs & derivatives; Flutamide - chemistry; Flutamide - metabolism; Flutamide - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression - drug effects; Injections, Subcutaneous; Medical sciences; Mice; Mice, Inbred ICR; Mifepristone - chemistry; Mifepristone - pharmacology; Molecular Structure; Progesterone - administration & dosage; Progesterone - antagonists & inhibitors; Progesterone - pharmacology; Reverse Transcriptase Polymerase Chain Reaction - methods; RNA, Messenger - genetics; RNA, Messenger - metabolism; S100 Calcium Binding Protein G - biosynthesis; S100 Calcium Binding Protein G - genetics; Teratology. Teratogens; Time Factors; Toxicology; Up-Regulation - drug effects; Up-Regulation - genetics; Uterus - drug effects; Uterus - metabolism
• ISSN: 0890-6238; 1873-1708
• DOI: 10.1016/j.reprotox.2006.04.015

A calcium binding protein, calbindin-D9k (CaBP-9k), is a cytosolic protein and regulated by steroid hormones in the reproductive tissues. Mouse CaBP-9k gene was predominantly regulated by progesterone (P4), whereas rat CaBP-9k was mainly regulated by 17beta-estradiol (E2) in the uterus. The induction of CaBP-9k can be employed as a biomarker for steroidal substrates as endocrine disruptors (EDs). Flutamide (FLU) is a non-steroidal anti-androgen or pro-drug that is rapidly metabolized to hydroxyflutamide, which may have both an anti-androgenic and anti-progestogenic activities. Thus, in the present study, we employed immature mice (14-day-old) subcutaneously injected with P4 (20 mg/kg/day) and/or FLU (5 mg/kg/day) for 3 consecutive days in the presence or absence of RU486, a pure PR antagonist (30 mg/kg/day), to analyze uterine CaBP-9k expression in this model. When immature mice were treated with P4, the expression levels of CaBP-9k mRNA and protein were significantly increased by P4. P4-induced expression levels of CaBP-9k mRNA and protein were abolished by FLU, in part, suggesting that FLU is a partial antagonist of P4 in the regulation of uterine CaBP-9k in immature mice. In addition, P4-induced CaBP-9k expression was completely reversed by RU486. Increased expression levels of CaBP-9k mRNA and protein were maintained for 24h after final injection with P4 in a time-dependent manner. However, CaBP-9k mRNA rapidly disappeared after 48 h and its protein level is similar with its mRNA. Treatment with FLU suppressed partially P4-induced CaBP-9k mRNA and protein until 24 h. Taken together, these results indicate that FLU has an anti-progestogenic activity and plays a role as a partial antagonist of P4 in the regulation of uterine CaBP-9k in immature mouse model.