title: Temporal Properties of Cone ERGs of Pikachurin Null Mutant Mouse.
abstract: OBJECTIVE
  Pikachurin is an extracellular matrix-like protein located in the synaptic cleft of photoreceptors. Pikachurin null mutant (Pika-/-) mice have abnormal ON bipolar cell function. This study aimed to determine the contribution of the ON bipolar cell pathway (ON pathway) of Pika-/- mice to the flicker ERG response and, using vector analysis, identify how the contribution varies with the stimulus frequency.
  
  
  METHODS
  Flicker ERGs were recorded from wild-type (WT), Pika-/-, and mGluR6 null mutant (mGluR6-/-) mice. The frequency of stimulation was 3.906 to 31.250 Hz. The amplitude and phase of the fundamental components were obtained by harmonic and vector model analysis. The mGluR6-/- mice were used as a model wherein the ON pathway is known to be absent.
  
  
  RESULTS
  The amplitudes of the fundamental components of the Pika-/- mice were significantly smaller than those of WT mice for stimulation frequencies between 3.906 and 17.578 Hz. The phase of the fundamental components of the Pika-/- mice was between those of the WT and mGluR6-/- mice. Vector analyses showed that the functioning of the ON pathway of Pika-/- mice was 12% to 25% of that of the WT mice at low frequencies (i.e., <15.625 Hz); however, it was reduced to noise level at frequencies >17.578 Hz.
  
  
  CONCLUSIONS
  Vector model analysis can determine the degree of contribution of the ON pathway of Pika-/- mice to flicker ERG response and may be useful for determining the retinal function in mice models with abnormalities of the ON pathway.
authors.affiliation: Department of Ophthalmology Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Kominami
authors.affiliation: Department of Ophthalmology Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ueno
authors.affiliation: Department of Ophthalmology Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Ayami
authors.initials: A
authors.lastname: Nakanishi
authors.affiliation: Department of Ophthalmology Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Azusa
authors.initials: A
authors.lastname: Kominami
authors.affiliation: Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Mineo
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Furukawa
authors.affiliation: Department of Ophthalmology Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Terasaki
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D004195:Disease Models, Animal; D004596:Electroretinography / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008817:Mice, Mutant Strains; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; C553232:pikachurin protein, mouse