Journal Article

Estrogen and Tamoxifen Protect against Mn-Induced Toxicity in Rat Cortical Primary Cultures of Neurons and Astrocytes

Eun-Sook Y. Lee, Zhaobao Yin, Dejan Milatovic, Haiyan Jiang and Michael Aschner

in Toxicological Sciences

Volume 110, issue 1, pages 156-167
Published in print July 2009 | ISSN: 1096-6080
Published online April 2009 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/kfp081
Estrogen and Tamoxifen Protect against Mn-Induced Toxicity in Rat Cortical Primary Cultures of Neurons and Astrocytes

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Chronic exposure to manganese (Mn) leads to a neurological disorder, manganism, which shares multiple common features with idiopathic Parkinson disease (IPD). 17β-Estradiol (E2) and some selective estrogen receptor modulators, including tamoxifen (TX), afford neuroprotection in various experimental models of neurodegeneration. However, the neuroprotective effects and mechanisms of E2/TX in Mn-induced toxicity have yet to be documented. Herein, we studied the ability of E2/TX to protect rat cortical primary neuronal and astroglial cultures from Mn-induced toxicity. Cell viability, Western blot, and reactive oxygen species (ROS) generation were assessed. Results established that both E2 (10nM) and TX (1μM) attenuated Mn-induced toxicity. The protective effects of E2/TX were more pronounced in astrocytes versus neurons. The E2-mediated attenuation of Mn-induced ROS generation in astrocytes at 6-h treatment (where no cell death was detected) was mediated by a classical estrogen receptor (ER) pathway and the TX-mediated effect on Mn-induced ROS generation was not mediated via classical ER-dependent mechanisms and likely by its antioxidant properties. The phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway was involved in both E2- and TX-induced attenuation of Mn-induced ROS formation (6 h) in astrocytes. Treatments with Mn for a longer duration (24 h) led to significant cell death, and the protective effects of E2 and TX were (1) not mediated by a classical ER pathway and (2) associated with activation of both mitogen-activated protein kinase/extracellular signal-regulated kinase and PI3K/Akt signaling pathways. Taken together, the results suggest that both E2 and TX offer effective therapeutic means for neuroprotection against Mn-induced toxicity.

Keywords: neuroprotection; oxidative stress; kinase (MAPK/ERK); PI3K/Akt; tamoxifen; 17β-estradiol

Journal Article.  5438 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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