title: Effects of estrogen on synapsin I distribution in developing hypothalamic neurons.
abstract: Estradiol (17beta-estradiol, E(2)) plays an essential role in sexual differentiation of the rodent brain. The purpose of the present study was to investigate the effects of E(2) on developing hypothalamic neurons by focusing on a presynaptic protein, synapsin I. We applied E(2) to cultured hypothalamic cells removed from fetal rats and investigated resultant effects upon synapsin I. Our immunocytochemical study revealed that administration of E(2) increased the dendritic area ('MAP2-area') and synaptic area detected as dot-like staining of synapsin I ('synapsin I-area'). However, immunoblotting and real-time PCR showed that E(2) did not increase both protein and mRNA expression levels of synapsin I. Studies with cyclohexamide (CHX), membrane impermeable E(2) (E(2)-BSA), and an estrogen receptor (ER) antagonist ICI 182,780 indicated that E(2) affected the synapsin I-area mainly via a non-genomic pathway mediated by membrane ER. Immunoblotting showed that E(2) suppressed phosphorylation of synapsin I at residues Ser-9, Ser-553, and Ser-603. On the other hand, E(2) did not affect phosphorylation of synapsin I at Ser-62, Ser-67 and Ser-549. The present study suggests that E(2) affects localization of synapsin I in hypothalamic neurons by altering site-specific phosphorylation of synapsin I, which is likely mediated by membrane ER.
authors.affiliation: Department of Life Sciences, Toyo University, 1-1-1 Itakura, Oura, Gunma 374-0193, Japan; Bio-Nano Electronic Research Centre, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585, Japan. r-kaneko@toyonet.toyo.ac.jp
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Ohtani-Kaneko
authors.forename: Makiko
authors.initials: M
authors.lastname: Iwafuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Iwakura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Muraoka
authors.forename: Makoto
authors.initials: M
authors.lastname: Yokosuka
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiga
authors.forename: Chiho
authors.initials: C
authors.lastname: Watanabe
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D048430:Cell Shape; D002478:Cells, Cultured; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D000077267:Fulvestrant; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism; D016704:Synapsins / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D016704:Synapsins; D000077267:Fulvestrant; D004958:Estradiol