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Visual System

開催日 2014/9/11
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Expression pattern of voltage-gated sodium channel subtypes in dopaminergic amacrine cells in the rat retina

  • P1-165
  • 金子 優子 / Yuko Kaneko:1,2 青葉-藤牧 香代 / Kayo Fujimaki-Aoba:2 渡辺 修一 / Shu-Ich Watanabe:2 
  • 1:埼玉医大・保健医療・看護 / Fac Health and Medical Care, Saitama Medical Univ, Saitama, Japan 2:埼玉医大・医・生理 / Dept Physiol, Fac Med, Saitama Medical Univ, Saitama, Japan 

Retinal ganglion cells (RGCs) and subsets of retinal amacrine cells, including AII amacrine cells and dopaminergic amacrine (DA) cells, generate TTX-sensitive action potentials evoked by light stimulus. In RGCs, various types of Navα (voltage-gated sodium channel α subunit) mRNAs (Nav1.1-1.3, 1.6) are expressed (Fjell et al., 1997; Boiko et al., 2003). Distinct sodium channel α subunits localized differentially to the specific region of the same RGC axons (Boiko et al., 2001, 2003; Van Wart et al. 2007). Van Wart et al. (2007) showed that Nav1.1 and Nav1.6 localized in the proximal and distal portion of the axon initial segment (AIS) of RGCs, respectively. In contrast, AII amacrine cells mainly express Nav1.1 mRNA (Kaneko and Watanabe, 2007). Recently, Wu et al. (2011) found that AII amacrine cells have an axon initial segment-like process where Nav1.1 is localized. In DA cells, distribution of the subtypes is still unknown. To identify the subtypes, we performed in situ hybridization and immunohistochemistry using anti-tyrosine hydroxylase (TH) antibody on the rat retina. Double-labeling for pan-specific anti-Navα (PAN) antibody and anti-TH antibody was also performed. In this study, we found that subset of DA cells expressed Nav1.2. Small number of DA cells expressed Nav1.6 and Nav1.3. No Nav1.1-positive DA cells were observed. Furthermore, we found that DA cells had a PAN-labeled process. Our results suggest that DA cells are not characterized by expression of single subtype of Navα (like AII amacrine cells). It might be possible that there are specific combinations of more than one subtype of Navα in one process of each DA cell.

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