H
Hirotaka Ishii
Researcher at Nippon Medical School
Publications - 58
Citations - 2410
Hirotaka Ishii is an academic researcher from Nippon Medical School. The author has contributed to research in topics: Alternative splicing & Exon. The author has an hindex of 19, co-authored 52 publications receiving 2226 citations. Previous affiliations of Hirotaka Ishii include University of Tokyo.
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Journal ArticleDOI
Adult male rat hippocampus synthesizes estradiol from pregnenolone by cytochromes P45017α and P450 aromatase localized in neurons
Yasushi Hojo,Taka-aki Hattori,Taihei Enami,A. Furukawa,Kumiko Suzuki,Hirotaka Ishii,Hideo Mukai,John H. Morrison,William G.M. Janssen,Shiro Kominami,Nobuhiro Harada,Tetsuya Kimoto,Suguru Kawato +12 more
TL;DR: Results imply that 17beta-estradiol is synthesized by P45017alpha and P450 aromatase localized in hippocampal neurons from endogenous cholesterol, and may be regulated by a glutamate-mediated synaptic communication that evokes Ca(2+) signals.
Journal ArticleDOI
Rapid modulation of long-term depression and spinogenesis via synaptic estrogen receptors in hippocampal principal neurons.
Hideo Mukai,Tomokazu Tsurugizawa,Gen Murakami,Shiro Kominami,Hirotaka Ishii,Mari Ogiue-Ikeda,Norio Takata,Nobuaki Tanabe,A. Furukawa,Yasushi Hojo,Yuuki Ooishi,John H. Morrison,William G.M. Janssen,John A. Rose,Pierre Chambon,Shigeaki Kato,Shunsuke Izumi,Takeshi Yamazaki,Tetsuya Kimoto,Suguru Kawato +19 more
TL;DR: Two types of independent synaptic plasticity, long‐term depression and spinogenesis, were investigated, in response to 17β‐estradiol and agonists of estrogen receptors using hippocampal slices from adult male rats, and it was demonstrated that estradiol rapidly enhanced LTD not only in CA1 but also in CA3 and dentate gyrus.
Journal ArticleDOI
Estrogen synthesis in the brain—Role in synaptic plasticity and memory
Yasushi Hojo,Gen Murakami,Hideo Mukai,Shimpei Higo,Yusuke Hatanaka,Mari Ogiue-Ikeda,Hirotaka Ishii,Tetsuya Kimoto,Suguru Kawato +8 more
TL;DR: Estrogen modulates memory-related synaptic plasticity not only slowly but also rapidly in the hippocampus, and ERalpha, but not ERbeta, induces the same enhancement/suppression effects on both spinogenesis and LTD.
Journal ArticleDOI
Comparison between Hippocampus-Synthesized and Circulation-Derived Sex Steroids in the Hippocampus
Yasushi Hojo,Shimpei Higo,Hirotaka Ishii,Yuuki Ooishi,Hideo Mukai,Gen Murakami,Toshihiro Kominami,Tetsuya Kimoto,Seijiro Honma,Donald Poirier,Suguru Kawato +10 more
TL;DR: It is suggested that male hippocampal E2 synthesis pathway may be androstenedione --> T --> E2 or dehydroepiandrosterone --> and Frostenediol --> T ― E2 but not androstensione --> E1 --> E 2.
Journal ArticleDOI
Hippocampal cytochrome P450s synthesize brain neurosteroids which are paracrine neuromodulators of synaptic signal transduction.
Keisuke Shibuya,Norio Takata,Yasushi Hojo,A. Furukawa,Nobuaki Yasumatsu,Tetsuya Kimoto,Taihei Enami,Kumiko Suzuki,Nobuaki Tanabe,Hirotaka Ishii,Hideo Mukai,Taiki Takahashi,Taka-aki Hattori,Suguru Kawato +13 more
TL;DR: Hippocampal pyramidal neurons and granule neurons of adult male rats are equipped with a complete machinery for the synthesis of pregnenolone, dehydroepiandrosterone, 17beta-estradiol and testosterone as well as their sulfate esters, promising neuromodulators that may either activate or inactivate neuron-neuron communication, thereby mediating learning and memory in the hippocampus.