Estrogenic activity of zinc pyrithione: an in vivo and in vitro study

Zinc pyrithione (ZP) is commonly used to prevent dandruff and seborrheic dermatitis. Many consumers are exposed daily to high doses of ZP, causing serious concerns about its toxicity. The reproductive and developmental toxicities were previously reported in pregnant rats. However, the estrogenic activity of ZP at varying degrees of exposure has been rarely studied. Thus, we performed an uterotrophic assay, E-screen assay, and gene expression profiling to assess the estrogenic activity of ZP. For the uterotrophic assay, ZP (2, 10, or 50 mg/kg/d) was subcutaneously administered to ovariectomized rats every day for three days. Uteri were extracted 24 hours after the last dose. Then, wet and blotted uterine weights were measured. For the E-screen essay, MCF-7 cells (a breast cancer cell line) were exposed to 10⁻⁹ to 10⁻⁶ M of ZP, and cell proliferation was then measured. For the gene expression analysis, changes of gene expression levels in uterine samples taken for the uterotrophic assay were analyzed. In the uterotrophic assay, the concentration of ZP had no significant effect on uterine weight. In the E-screen assay, ZP at any concentration showed no significant increase in MCF-7 cell proliferation, compared to the control group. However, 10⁻⁶ M of ZP significantly reduced cell viability. The changes in gene expression slightly differed between the ZP and control groups. The in vivo and in vitro assays, together with gene expression analysis, demonstrated that ZP showed no significant estrogenic activity.

Estrogenic activity of zinc pyrithione: an in vivo and in vitro study

Zinc pyrithione (ZP) is commonly used to prevent dandruff and seborrheic dermatitis. Many consumers are exposed daily to high doses of ZP, causing serious concerns about its toxicity. The reproductive and developmental toxicities were previously reported in pregnant rats. However, the estrogenic activity of ZP at varying degrees of exposure has been rarely studied. Thus, we performed an uterotrophic assay, E-screen assay, and gene expression profiling to assess the estrogenic activity of ZP. For the uterotrophic assay, ZP (2, 10, or 50 mg/kg/d) was subcutaneously administered to ovariectomized rats every day for three days. Uteri were extracted 24 hours after the last dose. Then, wet and blotted uterine weights were measured. For the E-screen essay, MCF-7 cells (a breast cancer cell line) were exposed to 10⁻⁹ to 10⁻⁶ M of ZP, and cell proliferation was then measured. For the gene expression analysis, changes of gene expression levels in uterine samples taken for the uterotrophic assay were analyzed. In the uterotrophic assay, the concentration of ZP had no significant effect on uterine weight. In the E-screen assay, ZP at any concentration showed no significant increase in MCF-7 cell proliferation, compared to the control group. However, 10⁻⁶ M of ZP significantly reduced cell viability. The changes in gene expression slightly differed between the ZP and control groups. The in vivo and in vitro assays, together with gene expression analysis, demonstrated that ZP showed no significant estrogenic activity.

Estrogenic activities of four components from pregnant mare’s urine extract / 中国药理学通报

Aim To investigate the estrogenic activities of four components from pregnant mare’s urine extract. Methods The estrogenic activities of four components were assessed using two in vitro tests:the MCF-7 cell proliferation assay (E-screen test)and the luciferase transfected CHO cell gene reporter assay.In the lucifer-ase reporter gene assay,the reporter gene plasmids PGM-ERE-Luc and ERαor ERβand a control plasmid (pRL-cmv)were transiently co-transfected into CHO cells to establish an ERα-or ERβ-cell screening system which was used to measure estrogenic activity of four compounds.Results MCF-7 cells treated with HP, DHP,PT and HA significantly proliferated,thereby of-fering in vitro evidence for the estrogenic activities of HP,DHP,PT and HA,and they showed dose-depend-ent activities.Compared EC50 of PE and RPE with that of E2 ,HP,DHP,PT and HA exerted relatively weak estrogenic activities.The in vitro ER-mediated reporter gene assay revealed that HP,DHP,PT and HA dis-played estrogenic activities mediated by ERβor ERα. Compared with the EC50 of E2 ,HP,DHP,PT and HA exhibited lower estrogenic potencies.Conclusion HP, DHP,PT and HA possess weaker estrogenic activities than E2 .