title: Estrogen and androgen protection of human neurons against intracellular amyloid beta1-42 toxicity through heat shock protein 70.
abstract: Intracellular amyloidbeta peptide (iAbeta1-42) accumulates in the Alzheimer's disease brain before plaque and tangle formation (Gouras et al., 2000) and is extremely toxic to human neurons (Zhang et al., 2002). Here, we investigated whether androgen and estrogen could prevent iAbeta1-4) toxicity, because both these hormones have a wide range of neuroprotective actions. At physiological concentrations, 17-beta-estradiol, testosterone, and methyl testosterone reduce iAbeta1-42-induced cell death by 50% in neurons treated after the injection and by 80-90% in neurons treated 1 hr before the injection. The neuroprotective action of the hormones is mediated by receptors, because the estrogen receptor (ER) antagonist tamoxifen and the androgen receptor (AR) antagonist flutamide completely block the estrogen- and androgen-mediated neuroprotection, respectively. Transcriptional activity is required for the neuroprotective action, because dominant negative forms of the receptors that block the transcriptional activity of the ER and AR prevent estrogen- and androgen-mediated neuroprotection. Proteomics followed by Western blot analyses identified increased levels of heat shock protein 70 (Hsp70) in testosterone- and estrogen-treated human neurons. Comicroinjection of Hsp70 with the iAbeta1-42 blocks the toxicity of iAbeta1-42. We conclude that estrogen and androgens protect human neurons against iAbeta1-42 toxicity by increasing the levels of Hsp70 in the neurons.
authors.affiliation: Department of Neurology, McGill University, Montreal QB H3A 1B1, Canada.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Nathalie
authors.initials: N
authors.lastname: Champagne
authors.forename: Lenore K
authors.initials: LK
authors.lastname: Beitel
authors.forename: Cynthia G
authors.initials: CG
authors.lastname: Goodyer
authors.forename: Mark
authors.initials: M
authors.lastname: Trifiro
authors.forename: Andréa
authors.initials: A
authors.lastname: LeBlanc
mesh_terms: D016229:Amyloid beta-Peptides / Q000009:adverse effects* / Q000378:metabolism; D000726:Androgen Antagonists / Q000494:pharmacology; D059002:Androgen Receptor Antagonists; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018076:DNA, Complementary; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D020287:In Situ Nick-End Labeling; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology; D011959:Receptors, Estradiol / Q000037:antagonists & inhibitors; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D016229:Amyloid beta-Peptides; D000726:Androgen Antagonists; D059002:Androgen Receptor Antagonists; D018076:DNA, Complementary; D004965:Estrogen Antagonists; D018840:HSP70 Heat-Shock Proteins; D018696:Neuroprotective Agents; D011959:Receptors, Estradiol; D013739:Testosterone; D004958:Estradiol