The expression of Hedgehog genes (Ihh, Dhh) and Hedgehog target genes (Ptc1, Gli1, Coup-TfII) is affected by estrogenic stimuli in the uterus of immature female rats.

The objective of this study was to investigate the effects of estrogen receptor (ER) agonists and an ER antagonist on the expression of Hedgehog genes (Indian hedgehog: Ihh; Desert hedgehog: Dhh) and Hedgehog target genes (Patched 1: Ptc1; glioma-associated oncogene homolog 1: Gli1; chicken ovalbumin upstream promoter transcription factor II: Coup-TfII) in the rat uterus. Immature female rats were administered once with 17alpha-ethynyl estradiol (EE, an ER agonist), propyl pyrazole triole (PPT, an ERalpha-selective agonist), diarylpropionitrile (DPN, an ERbeta-selective agonist), or ICI 182,780 (an ER antagonist). Expression of mRNA for Ihh, Dhh, and Ptc1 was dose-dependently downregulated by EE in the uterus of immature rats, mediated by ER as confirmed by coadministration of ICI 182,780. The mRNA expression levels of Ptc1, Gli1, and Coup-TfII were simultaneously downregulated during the period in which the mRNA expression levels of Ihh and Dhh were downregulated in the uterus after administration of EE. PPT downregulated the transcription of Ihh, Dhh, Ptc1, Gli1, and Coup-TfII, indicating that expression of these genes was regulated by the ERalpha-dependent pathway. DPN also downregulated the transcription of Ihh and Dhh, although the effect was weaker than that of PPT, indicating that the regulation of uterine Ihh and Dhh transcription was also affected by the ERbeta-dependent pathway. These results suggest that the expression of Hedgehog genes (Ihh, Dhh) and Hedgehog target genes (Ptc1, Gli1, Coup-TfII) is affected by estrogenic stimuli in the uterus of immature female rats.

Differential expression patterns of Wnt and beta-catenin/TCF target genes in the uterus of immature female rats exposed to 17alpha-ethynyl estradiol.

To characterize the effects of an estrogen receptor (ER) agonist on the gene expressions in the uterus, immature female rats were administered once orally with 17alpha-ethynyl estradiol (EE, 3 mug/kg), a potent ER agonist. We focused on four categories of sex steroid hormone receptor genes: well-known estrogen target genes, Wnt genes, and beta-catenin/T-cell factor (TCF) target genes. ERalpha, ERbeta, progesterone receptor, and androgen receptor mRNAs were all downregulated at 24 and/or 48 h after EE administration. Complement C3 and insulin-like growth factor 1 mRNAs were markedly induced after EE administration. Although the time courses of Wnt4, Wnt5a, and Wnt7a mRNA status varied until 12 h after EE administration, all of them were simultaneously downregulated at 24 and 48 h. The remarkable downregulation of Wnt7a mRNA in response to EE was considered to be important to understand the various uterine phenomena affected by ER agonists. In the beta-catenin/TCF target genes, the downregulation of anti-Mullerian hormone type 2 receptor and bone morphogenetic protein 4 mRNA after EE administration appeared to be closely related to the downregulation of Wnt7a. The upregulation of cyclin D1 and follistatin mRNA at the early phase after EE administration was considered to have been affected by the upregulation of Wnt4. These results indicate that an ER agonist influences not only the mRNA expression of sex steroid hormone receptor genes and well-known estrogen target genes but also Wnt genes (Wnt4, Wnt5a, Wnt7a) and beta-catenin/TCF target genes in the uterus of immature rats, indicating that their molecules are the potential players affected by estrogenic stimuli.

[Examination of sex-hormonal activity of some additives for PVDC film].

Stabilizers (epoxidized linseed oil and epoxidized soybean oil) and plasticizers (acetyl tributyl citrate, diacetyl monolauryl glyceride and dibutyl sebacate) commonly used in polyvinylidene chloride (PVDC) films and extracts of such films were investigated for estrogenic and androgenic activity by means of estrogen receptor (ER) and androgen receptor (AR) competitive ligand-binding assays. Further, in in vivo experiments, ovariectomized Sprague-Dawley rats were observed for uterine wet weight change, uterine endometrium hyperplasia and vaginal mucosa cornification, following administration of each test compound or extract orally (0.5 or 500 mg/kg) or subcutaneously (0.5 or 100 mg/kg). No significant response or change was observed with any of the test compounds or extracts, either in vitro or in vivo. The results thus indicate that neither the stabilizers and plasticizers used in PVDC films, nor their extracts, exert sex-hormonal activity.

Comparison of toxicity studies based on the draft protocol for the 'Enhanced OECD Test Guideline no. 407' and the research protocol of 'Pubertal Development and Thyroid Function in Immature Male Rats' with 6-n-propyl-2-thiouracil.

Two repeated-dose studies of 6-n-propyl-2-thiouracil (PTU) in male rats based on the research protocol 'Pubertal Development and Thyroid Function in Immature Male Rats' (pubertal assay) proposed by the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC) and the draft protocol of the 'Enhanced OECD Test Guideline 407' (enhanced TG 407) were performed to investigate the suitability of both assays as screening methods for the detection of endocrine-mediated effects and to compare their sensitivity for the endocrine-mediated effects. In the pubertal assay, PTU at doses of 0, 0.01, or 1 mg/kg per day was orally administered to male Sprague-Dawley rats for 30 days, starting at 23 days of age. In the enhanced TG 407 the same doses of PTU were orally administered to male Sprague-Dawley rats for 28 days, starting at 7 weeks of age. In the pubertal assay, decreased serum thyroxine (T4) and triiodothyronine (T3), increased thyroid and pituitary weights, hypertrophy of follicular epithelial cells in the thyroid, and increased basophilic cells in the pituitary were detected as endocrine-mediated effects of PTU in the 1 mg/kg group. In the enhanced TG 407, decreased T4 and T3 were detected in both the 0.01 and 1 mg/kg groups, together with increased thyroid-stimulating hormone in the 1 mg/kg group, increased thyroid and pituitary weights in the 1 mg/kg group, and hypertrophy of follicular epithelial cells in the thyroid and increased basophilic cells in the pituitary of the 1 mg/kg group. Thus, among the parameters tested, the thyroid hormone levels, organ weight changes, and the histopathological assessment allowed detection of the endocrine-related effects of PTU in both the pubertal assay and the enhanced TG 407, but the sensitivity of the hormone analysis was higher in the latter.