Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells
<p>Abstract</p> <p>Background</p> <p>Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the resp...
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| Format: | Article |
| Language: | English |
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BMC
2010-10-01
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| Series: | Environmental Health |
| Online Access: | http://www.ehjournal.net/content/9/1/61 |
| _version_ | 1828411631977103360 |
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| author | Watson Cheryl S Kochukov Mikhail Jeng Yow-Jiun |
| author_facet | Watson Cheryl S Kochukov Mikhail Jeng Yow-Jiun |
| author_sort | Watson Cheryl S |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the responses to these compounds are typically measured individually, they usually contaminate organisms that already have endogenous estrogens present. Therefore, we used quantitative medium-throughput screening assays to measure the effects of physiologic estrogens in combination with these xenoestrogens.</p> <p>Methods</p> <p>We studied the effects of low concentrations of endogenous estrogens (estradiol, estriol, and estrone) at 10 pM (representing pre-development levels), and 1 nM (representing higher cycle-dependent and pregnancy levels) in combinations with the same levels of xenoestrogens in GH<sub>3</sub>/B6/F10 pituitary cells. These levels of xenoestrogens represent extremely low contamination levels. We monitored calcium entry into cells using Fura-2 fluorescence imaging of single cells. Prolactin release was measured by radio-immunoassay. Extracellular-regulated kinase (1 and 2) phospho-activations and the levels of three estrogen receptors in the cell membrane (ERα, ERβ, and GPER) were measured using a quantitative plate immunoassay of fixed cells either permeabilized or nonpermeabilized (respectively).</p> <p>Results</p> <p>All xenoestrogens caused responses at these concentrations, and had disruptive effects on the actions of physiologic estrogens. Xenoestrogens reduced the % of cells that responded to estradiol via calcium channel opening. They also inhibited the activation (phosphorylation) of extracellular-regulated kinases at some concentrations. They either inhibited or enhanced rapid prolactin release, depending upon concentration. These latter two dose-responses were nonmonotonic, a characteristic of nongenomic estrogenic responses.</p> <p>Conclusions</p> <p>Responses mediated by endogenous estrogens representing different life stages are vulnerable to very low concentrations of these structurally related xenoestrogens. Because of their non-classical dose-responses, they must be studied in detail to pinpoint effective concentrations and the directions of response changes.</p> |
| first_indexed | 2024-12-10T12:33:55Z |
| format | Article |
| id | doaj.art-1d7e75ffcf5d4742be247a512564e090 |
| institution | Directory Open Access Journal |
| issn | 1476-069X |
| language | English |
| last_indexed | 2024-12-10T12:33:55Z |
| publishDate | 2010-10-01 |
| publisher | BMC |
| record_format | Article |
| series | Environmental Health |
| spelling | doaj.art-1d7e75ffcf5d4742be247a512564e0902022-12-22T01:48:43ZengBMCEnvironmental Health1476-069X2010-10-01916110.1186/1476-069X-9-61Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cellsWatson Cheryl SKochukov MikhailJeng Yow-Jiun<p>Abstract</p> <p>Background</p> <p>Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the responses to these compounds are typically measured individually, they usually contaminate organisms that already have endogenous estrogens present. Therefore, we used quantitative medium-throughput screening assays to measure the effects of physiologic estrogens in combination with these xenoestrogens.</p> <p>Methods</p> <p>We studied the effects of low concentrations of endogenous estrogens (estradiol, estriol, and estrone) at 10 pM (representing pre-development levels), and 1 nM (representing higher cycle-dependent and pregnancy levels) in combinations with the same levels of xenoestrogens in GH<sub>3</sub>/B6/F10 pituitary cells. These levels of xenoestrogens represent extremely low contamination levels. We monitored calcium entry into cells using Fura-2 fluorescence imaging of single cells. Prolactin release was measured by radio-immunoassay. Extracellular-regulated kinase (1 and 2) phospho-activations and the levels of three estrogen receptors in the cell membrane (ERα, ERβ, and GPER) were measured using a quantitative plate immunoassay of fixed cells either permeabilized or nonpermeabilized (respectively).</p> <p>Results</p> <p>All xenoestrogens caused responses at these concentrations, and had disruptive effects on the actions of physiologic estrogens. Xenoestrogens reduced the % of cells that responded to estradiol via calcium channel opening. They also inhibited the activation (phosphorylation) of extracellular-regulated kinases at some concentrations. They either inhibited or enhanced rapid prolactin release, depending upon concentration. These latter two dose-responses were nonmonotonic, a characteristic of nongenomic estrogenic responses.</p> <p>Conclusions</p> <p>Responses mediated by endogenous estrogens representing different life stages are vulnerable to very low concentrations of these structurally related xenoestrogens. Because of their non-classical dose-responses, they must be studied in detail to pinpoint effective concentrations and the directions of response changes.</p>http://www.ehjournal.net/content/9/1/61 |
| spellingShingle | Watson Cheryl S Kochukov Mikhail Jeng Yow-Jiun Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells Environmental Health |
| title | Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells |
| title_full | Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells |
| title_fullStr | Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells |
| title_full_unstemmed | Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells |
| title_short | Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells |
| title_sort | combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses prolactin release and membrane estrogen receptor trafficking in rat pituitary cells |
| url | http://www.ehjournal.net/content/9/1/61 |
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