title: Pathway-dependent modulation by P2-purinoceptors in the mouse retina.
abstract: Adenosine trisphosphate (ATP) activates purinoceptors and acts as a neurotransmitter in the nervous system. In the retina, we previously reported that the immunohistochemical distribution of the subset of P2-purinoceptors differs between the ON and OFF pathways. Here, we investigated whether ATP activates P2-purinoceptors and modulates the physiological function of the mouse retina. We also examined if signal processing by P2-purinoceptors is pathway specific. Results showed that ATP activated both ON- and OFF-cholinergic amacrine cells. However, responses in OFF-cholinergic amacrine cells were greater than those in ON-cholinergic amacrine cells. Pharmacological studies in OFF-cholinergic amacrine cells showed that the response of OFF-cholinergic amacrine cells is mediated P2X(2)-purinoceptors. Further, ATP increased gamma-aminobutyric acid (GABA)ergic inhibitory postsynaptic currents (IPSCs) in OFF- but not ON-cholinergic amacrine cells. The increase in GABAergic IPSCs was mediated by P2-purinoceptors. P2-purinoceptor-mediated signals suppressed OFF ganglion cells but activated ON ganglion cells. Our findings indicate that ATP physiologically modulates signal processing of the ON and OFF pathways in a pathway-specific manner through P2-purinoceptors.
authors.affiliation: Department of Physiology, Keio University School of Medicine, Tokyo 160-8582, Japan. mkaneda@a5.keio.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Kaneda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ishii
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Hosoya
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D018756:GABA Antagonists / Q000378:metabolism; D018684:Glycine Agents / Q000378:metabolism; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D011724:Pyridazines / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013331:Strychnine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D018756:GABA Antagonists; D018684:Glycine Agents; D011724:Pyridazines; D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D005680:gamma-Aminobutyric Acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; C049853:gabazine; D013331:Strychnine