title: Tamoxifen protects male mice nigrostriatal dopamine against methamphetamine-induced toxicity.
abstract: The selective estrogen receptor modulator tamoxifen and estradiol were shown to protect nigrostriatal dopamine concentration loss by methamphetamine in female mice whereas male mice were protected only by tamoxifen. The present study examined the protective properties of tamoxifen in male mice on several nigrostriatal dopaminergic markers and body temperature. Intact male mice were administered 12.5 or 50 microg tamoxifen 24 h before methamphetamine treatment. Basal body temperatures of male mice remained unchanged by the tamoxifen treatment. Methamphetamine reduced striatal dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid concentrations, striatal and substantia nigra dopamine and vesicular monoamine transporter specific binding as well substantia nigra dopamine and vesicular monoamine transporter mRNA levels and increased striatal preproenkephalin mRNA levels. These methamphetamine effects were not altered by 12.5 microg tamoxifen except for increased striatal dopamine metabolites and turnover. Tamoxifen at 50 microg reduced the methamphetamine effect on striatal dopamine concentration, dopamine transporter specific binding and prevented the increase in preproenkephalin mRNA levels; in the substantia nigra tamoxifen prevented the decrease of dopamine transporter mRNA levels. The present results show a tamoxifen dose-dependent prevention of loss of various dopaminergic markers against methamphetamine-induced toxicity in male mice. Since this is the only known hormonal protection of male mice against methamphetamine toxicity, these findings provide important new information on specific parameters of nigrostriatal dopaminergic function preserved by tamoxifen.
authors.affiliation: Molecular Endocrinology and Oncology Research Center, Laval University Medical Center, CHUL, Quebec City, Quebec G1V 4G2, Canada.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Bourque
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Dean E
authors.initials: DE
authors.lastname: Dluzen
authors.forename: Thérèse
authors.initials: T
authors.lastname: Di Paolo
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004745:Enkephalins / Q000378:metabolism; D008297:Male; D008694:Methamphetamine / Q000633:toxicity*; D051379:Mice; D008815:Mice, Inbred Strains; D020258:Neurotoxicity Syndromes / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D011498:Protein Precursors / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D013378:Substantia Nigra / Q000187:drug effects* / Q000378:metabolism; D013629:Tamoxifen / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism