GABAC receptors are localized with microtubule-associated protein 1B in mammalian cone photoreceptors.
Protein MAP1B was recently reported to link GABA(C) receptors to the cytoskeleton at neuronal synapses. This interaction was demonstrated in the mammalian retina, where GABA(C) receptors were thought to be exclusively expressed in bipolar cells. Our previous studies on cultured photoreceptors suggested however the presence of GABA(C) receptors in cones. To further investigate GABA(C) receptor expression in cones, we measured GABA responses in mammalian photoreceptors in situ, and we examined the distribution of the receptor and that of protein MAP1B in the mammalian outer retina. Photoreceptors were recorded from flat-mounted retinas of retinal degeneration mice at an age when the retina becomes cone-dominated after rod cell death. GABA(A) and GABA(C)-gated currents were produced only in cones but not rods. Recording freshly dissociated retinal cells from wild-type C57 mice confirmed the presence of GABA(A) and GABA(C) receptors in cones. Immunohistochemical labeling of mouse and rat retinal sections localized GABA(C) receptors to cone terminals that were identified by peanut agglutinin lectin staining. As expected from previous studies on bipolar cells, the punctate immunostaining was not restricted to cone terminals in the outer plexiform layer. MAP1B immunolabeling was obtained in rat and pig retinas and was similarly found in cone terminals identified by the peanut agglutinin lectin staining. These results provide physiological and histological evidence that cones receive a GABA feedback in the mammalian retina and are consistent with the notion that protein MAP1B links GABA(C) receptors to the cytoskeleton at postsynaptic sites.
Pattnaik
B
B
Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, Institut National de la Santé et de la Recherche Médicale EMI 99-18, University Louis Pasteur, 67091 Strasbourg Cedex, France.
Jellali
A
A
Sahel
J
J
Dreyfus
H
H
Picaud
S
S
D000818:Animals; D002469:Cell Separation; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D018757:GABA Modulators / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008809:Mice, Inbred C3H; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010424:Pentobarbital; D010721:Phosphinic Acids / Q000494:pharmacology; D011724:Pyridazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D018079:Receptors, GABA / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000493:pharmacokinetics / Q000494:pharmacology
C101879:(1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018757:GABA Modulators; D058787:GABA-A Receptor Antagonists; C087200:GABA-C receptor; D008869:Microtubule-Associated Proteins; D010721:Phosphinic Acids; D011724:Pyridazines; D011725:Pyridines; D018079:Receptors, GABA; C085284:microtubule-associated protein 1B; D005680:gamma-Aminobutyric Acid; C049853:gabazine; D010424:Pentobarbital