Glycine receptors are functionally expressed on bullfrog retinal cone photoreceptors.
Using immunocytochemical and whole cell recording techniques, we examined expression of glycine receptors on bullfrog retinal cone photoreceptors. Immunofluorescence double labeling experiments conducted on retinal sections and isolated cell preparations showed that terminals and inner segments of cones were immunoreactive to both alpha1 and beta subunits of glycine receptors. Moreover, application of glycine induced a sustained inward current from isolated cones, which increased in amplitude in a dose-dependent manner, with an EC50 (concentration of glycine producing half-maximal response) of 67.3+/-4.9 microM, and the current was blocked by the glycine receptor antagonist strychnine, but not 5,7-dichlorokynurenic acid (DCKA) of 200 microM, a blocker of the glycine recognition site at the N-methyl-D-aspartate (NMDA) receptor. The glycine-induced current reversed in polarity at a potential close to the calculated chloride equilibrium potential, and the reversal potential was changed as a function of the extracellular chloride concentration. These results suggest that strychnine-sensitive glycine receptors are functionally expressed in bullfrog cones, which may mediate signal feedback from glycinergic interplexiform cells to cones in the outer retina.
Ge
L-H
LH
Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
Lee
S-C
SC
Liu
J
J
Yang
X-L
XL
D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005998:Glycine / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D011892:Rana catesbeiana / Q000033:anatomy & histology / Q000378:metabolism; D018009:Receptors, Glycine / Q000378:metabolism*; D051603:Recoverin / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013331:Strychnine / Q000494:pharmacology
D002712:Chlorides; D018684:Glycine Agents; D018009:Receptors, Glycine; D051603:Recoverin; D013331:Strychnine; D005998:Glycine