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  • Title: Bisphenol A Induces Agrp Gene Expression in Hypothalamic Neurons through a Mechanism Involving ATF3.
    Author: Loganathan N, McIlwraith EK, Belsham DD.
    Journal: Neuroendocrinology; 2021; 111(7):678-695. PubMed ID: 32575098.
    Abstract:
    BACKGROUND: Bisphenol A (BPA) is a ubiquitous endocrine disrupting chemical and obesogen. Although limited evidence exists of the effects of BPA on hypothalamic agouti-related peptide (AgRP) levels, the mechanisms underlying these effects remain unknown. Given that AgRP is a potent orexigenic neuropeptide, determining the mechanism by which BPA increases AgRP is critical to preventing the progression to metabolic disease. METHODS: Using quantitative reverse transcriptase polymerase chain reaction, we investigated the response of Agrp-expressing mouse hypothalamic cell lines to BPA treatment. The percentage of total BPA entering hypothalamic cells in culture was quantified using an enzyme-linked immunosorbent assay. In order to identify the mechanism underlying BPA-mediated changes in Agrp, siRNA knockdown of transcription factors, FOXO1, CHOP, ATF3, ATF4, ATF6, and small-molecule inhibitors of endoplasmic reticulum stress, JNK or MEK/ERK were used. RESULTS: BPA increased mRNA levels of Agrp in six hypothalamic cell lines (mHypoA-59, mHypoE-41, mHypoA-2/12, mHypoE-46, mHypoE-44, and mHypoE-42). Interestingly, only 18% of the total BPA in the culture medium entered the cells after 24 h, suggesting that the exposure concentration is much lower than the treatment concentration. BPA increased pre-Agrp mRNA levels, indicating increased Agrp transcription. Knockdown of the transcription factor ATF3 prevented BPA-mediated increase in Agrp, pre-Agrp, and in part Npy mRNA levels. However, chemical chaperone, sodium phenylbutyrate, JNK inhibitor, SP600125, or the MEK/ERK inhibitor PD0352901 did not block BPA-induced Agrp upregulation. CONCLUSION: Overall, these results indicate that hypothalamic Agrp is susceptible to dysregulation by BPA and implicate ATF3 as a common mediator of the orexigenic effects of BPA in hypothalamic neurons.
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