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Atrazine binds to the growth hormone-releasing hormone receptor and affects growth hormone gene expression.

Fakhouri WD, Nuñez JL, Trail F - Environ. Health Perspect. (2010)

Bottom Line: The treatment of rat pituitary cells with ATR, at environmentally relevant concentrations (1 ppb and 1 ppm), resulted in a reduction of GH expression.This effect appeared to result from the inhibition of GH gene transcription due to ATR binding to the GHRHR of the pituitary cells.These findings may lead to a better understanding of the hazards of environmental ATR contamination and inform efforts to develop guidelines for establishing safe levels in water systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824, USA.

ABSTRACT

Background: Atrazine (ATR), a commonly used herbicide in the United States, is widely distributed in water and soil because of its mobility through ecosystems and its persistence in the environment. ATR has been associated with defects in sexual development in animals, but studies on mammalian systems have failed to clearly identify a cellular target.

Objectives: Our goal in this study was to identify a ligand-binding receptor for ATR in pituitary cells that may explain the mechanism of action at the gene expression level.

Methods: We used pituitary cells from postnatal day 7 male rats and pituitary cell lines to study the effect of ATR on gene expression of growth hormone (GH), luteinizing hormone (LH), and prolactin (PRL) at RNA and protein levels. 14C-ATR was used to determine its specific binding to the growth hormone-releasing hormone receptor (GHRHR). The effect of ATR on structural proteins was visualized using immunofluorescent in situ staining.

Results: The treatment of rat pituitary cells with ATR, at environmentally relevant concentrations (1 ppb and 1 ppm), resulted in a reduction of GH expression. This effect appeared to result from the inhibition of GH gene transcription due to ATR binding to the GHRHR of the pituitary cells.

Conclusions: Identification of GHRHR as the target of ATR is consistent with the myriad effects previously reported for ATR in mammalian systems. These findings may lead to a better understanding of the hazards of environmental ATR contamination and inform efforts to develop guidelines for establishing safe levels in water systems.

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Protein levels of GH, LH, PRL, and GHRHR assayed in mouse AtT-20 pituitary cell culture 30 min after treatment with vehicle (DMSO; lanes 1 and 2), Dex (10 μM; lanes 3 and 4), ATR (1 ppm; lanes 5 and 6), or ATR (1 ppb; lanes 7 and 8). β-Actin protein was used as an internal loading control.
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f3-ehp-118-1400: Protein levels of GH, LH, PRL, and GHRHR assayed in mouse AtT-20 pituitary cell culture 30 min after treatment with vehicle (DMSO; lanes 1 and 2), Dex (10 μM; lanes 3 and 4), ATR (1 ppm; lanes 5 and 6), or ATR (1 ppb; lanes 7 and 8). β-Actin protein was used as an internal loading control.

Mentions: To test the effect of ATR on the final product of GH, LH, PRL, and GHRHR genes, we used Western blot analysis to detect the amount of proteins in pituitary cells 30 min after treatment. The amount of GH and LH protein in AtT-20 pituitary cell cultures was slightly reduced in cells treated with 1.0 ppm and 1.0 ppb ATR compared with the negative control (treated with the vehicle alone). In contrast, the amount of PRL was slightly increased in ATR-treated cells. The protein level of GHRHR was similar in all treatment groups (Figure 3).


Atrazine binds to the growth hormone-releasing hormone receptor and affects growth hormone gene expression.

Fakhouri WD, Nuñez JL, Trail F - Environ. Health Perspect. (2010)

Protein levels of GH, LH, PRL, and GHRHR assayed in mouse AtT-20 pituitary cell culture 30 min after treatment with vehicle (DMSO; lanes 1 and 2), Dex (10 μM; lanes 3 and 4), ATR (1 ppm; lanes 5 and 6), or ATR (1 ppb; lanes 7 and 8). β-Actin protein was used as an internal loading control.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2957919&req=5

f3-ehp-118-1400: Protein levels of GH, LH, PRL, and GHRHR assayed in mouse AtT-20 pituitary cell culture 30 min after treatment with vehicle (DMSO; lanes 1 and 2), Dex (10 μM; lanes 3 and 4), ATR (1 ppm; lanes 5 and 6), or ATR (1 ppb; lanes 7 and 8). β-Actin protein was used as an internal loading control.
Mentions: To test the effect of ATR on the final product of GH, LH, PRL, and GHRHR genes, we used Western blot analysis to detect the amount of proteins in pituitary cells 30 min after treatment. The amount of GH and LH protein in AtT-20 pituitary cell cultures was slightly reduced in cells treated with 1.0 ppm and 1.0 ppb ATR compared with the negative control (treated with the vehicle alone). In contrast, the amount of PRL was slightly increased in ATR-treated cells. The protein level of GHRHR was similar in all treatment groups (Figure 3).

Bottom Line: The treatment of rat pituitary cells with ATR, at environmentally relevant concentrations (1 ppb and 1 ppm), resulted in a reduction of GH expression.This effect appeared to result from the inhibition of GH gene transcription due to ATR binding to the GHRHR of the pituitary cells.These findings may lead to a better understanding of the hazards of environmental ATR contamination and inform efforts to develop guidelines for establishing safe levels in water systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824, USA.

ABSTRACT

Background: Atrazine (ATR), a commonly used herbicide in the United States, is widely distributed in water and soil because of its mobility through ecosystems and its persistence in the environment. ATR has been associated with defects in sexual development in animals, but studies on mammalian systems have failed to clearly identify a cellular target.

Objectives: Our goal in this study was to identify a ligand-binding receptor for ATR in pituitary cells that may explain the mechanism of action at the gene expression level.

Methods: We used pituitary cells from postnatal day 7 male rats and pituitary cell lines to study the effect of ATR on gene expression of growth hormone (GH), luteinizing hormone (LH), and prolactin (PRL) at RNA and protein levels. 14C-ATR was used to determine its specific binding to the growth hormone-releasing hormone receptor (GHRHR). The effect of ATR on structural proteins was visualized using immunofluorescent in situ staining.

Results: The treatment of rat pituitary cells with ATR, at environmentally relevant concentrations (1 ppb and 1 ppm), resulted in a reduction of GH expression. This effect appeared to result from the inhibition of GH gene transcription due to ATR binding to the GHRHR of the pituitary cells.

Conclusions: Identification of GHRHR as the target of ATR is consistent with the myriad effects previously reported for ATR in mammalian systems. These findings may lead to a better understanding of the hazards of environmental ATR contamination and inform efforts to develop guidelines for establishing safe levels in water systems.

Show MeSH