title: Physiological contribution of P2X receptors in postreceptoral signal processing in the mouse retina.
abstract: ATP activates P2X receptors and acts as a neurotransmitter in the nervous system. We have previously reported that P2X receptors modulate the firing rate of retinal ganglion cells. Since many subtypes of P2X receptors are distributed in the mouse retina, it is likely that the modulatory effects of P2X receptor-mediated signaling can occur at multiple synaptic levels in the retina. In this study, we investigated whether P2X receptors expressed between the photoreceptor layer and the inner nuclear layer in the mouse retina were physiologically functional, by electroretinography (ERG). In the combined rod-cone ERG and the scotopic ERG, intravitreal injection of PPADS, an antagonist of P2X receptors, had no effects on the amplitude of the a-wave, but decreased the amplitude of the b-wave. In the photopic ERG, intravitreal injection of PPADS significantly decreased the amplitude of both the a-wave and the b-wave. In ex vivo recordings, a decrease in the b-wave amplitude was observed at 20μM PPADS, confirming that the inhibition of the b-wave by intravitreal injection of PPADS is due to the inhibition of P2X receptors. Our findings suggest that P2X receptor-mediated signaling has a physiological effect in both the rod and the cone pathways in postreceptoral processing.
authors.affiliation: Department of Physiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan; Department of Ophthalmology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Ichinohe
authors.affiliation: Department of Physiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. Electronic address: tsishii@nms.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ishii
authors.affiliation: Department of Ophthalmology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Physiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kaneda
mesh_terms: D000818:Animals; D004596:Electroretinography; D008810:Mice, Inbred C57BL; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000502:physiology; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D058469:Receptors, Purinergic P2X / Q000502:physiology*; D012160:Retina / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D058920:Purinergic P2X Receptor Antagonists; D058469:Receptors, Purinergic P2X; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate
keywords: ATP; Electroretinogram; Mouse; Multi electrode array; P2X receptor; PPADS; Retina