Effects of estrogen on synapsin I distribution in developing hypothalamic neurons

• Published in: Neuroscience research Vol. 66; no. 2; pp. 180 - 188
• Main Authors: Ohtani-Kaneko, Ritsuko, Iwafuchi, Makiko, Iwakura, Takashi, Muraoka, Daisuke, Yokosuka, Makoto, Shiga, Takashi, Watanabe, Chiho
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.02.2010
• Subjects: Analysis of Variance; Animals; Blotting, Western; Cell culture; Cell Shape; Cells, Cultured; Estradiol; Estradiol - analogs & derivatives; Estradiol - pharmacology; Hypothalamus; Hypothalamus - cytology; Hypothalamus - drug effects; Hypothalamus - metabolism; Image Processing, Computer-Assisted; Immunohistochemistry; Microtubule-Associated Proteins - metabolism; Neurons - drug effects; Neurons - metabolism; Non-genomic pathway; Phosphorylation - drug effects; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sex differentiation; Synapse; Synapses - drug effects; Synapses - metabolism; Synapsin I; Synapsins - metabolism; Synapsin I; Cell culture; Synapse; Non-genomic pathway; Sex differentiation; Hypothalamus; Estradiol
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2009.10.012

Estradiol (17β-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.