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Oculomotor System

開催日 2014/9/11
時間 16:00 - 17:00
会場 Poster / Exhibition(Event Hall B)

Rac-GAP α-chimaerin 欠損マウスはピロカルピン低感受性を示す
Decreased susceptibility to pilocarpine in Rac-GAP α-chimaerin deficient mice

  • P1-158
  • 竹内 絵理 / Eri Takeuchi:1 畑中 朋美 / Tomomi Hatanaka:1 笹川 恵梨奈 / Erina Sasagawa:2 岩里 琢治 / Takuji Iwasato:3 糸原 重美 / Shigeyoshi Itohara:4 加藤 明 / Akira Katoh:1 
  • 1:東海大創造科学技術研究機構 / Institute of Innovative Science and Technology, Tokai Univ, Kanagawa, Japan 2:東海大学工学部生命科学科 / Dept Appl Biochem, Tokai Univ, Kanagawa, Japan 3:国立遺伝研個体遺伝形質遺伝 / Div of Neurogenet, NIG, Shizuoka, Japan 4:理研BSI行動遺伝学 / Lab for Behav Genet, RIKEN BSI, Saitama, Japan 

α-chimaerin (α-chimerin), a Rac-specific GTPase activating protein, plays a key role to wire neurons precisely in the brain. Indeed, miffy mice, α-chimaerin spontaneous null mutant mice, have abnormal midline crossing of corticospinal tract axons and abnormal spinal central pattern generators, resulting in exhibiting a rabbit hopping gait (Iwasato, 2007). A more recent study reported that when α2-chimaerin, one of two major isoforms of α-chimaerin and known as a gene causing Duane Retraction Syndrome, was knocked-down in neurons in oculomotor nuclei, its axon guidance was impaired in zebrafish (Clark, 2013). Here we found that miffy mice were significantly less sensitive to pilocarpine which induces myosis. Instillation of 1% pilocarpine hydrochloride into the eye shrank the pupil by 80% in wild-type mice, whereas miffy mice exhibited less than 40% shrinking of the pupil. The pupillary response to light occurred in miffy mice but the time course of the size change of the pupil was altered compared to wild-type mice. In addition, the effect of atropine to induce mydriasis seemed more profound in miffy mice than in wild-type mice.
Myosis is controlled by parasympathetic nerves innervating to sphincter muscles of the pupil, originated from oculomotor nuclei through ciliary ganglion, and mydriasis is controlled by sympathetic nerves. Our current results suggest that lacking of α-chimaerin altered mechanisms balanced by sympathetic and parasympathetic nerves to regulate the pupil size.

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