J Physiol Volume 571, Number 2, 391-401, March 1, 2006 DOI: 10.1113/jphysiol.2005.100891
Glycine receptors in a population of adult mammalian cones
E. Balse1,
L.-H. Tessier1,
V. Forster1,
M. J. Roux1,
J. A. Sahel1,2,3 and
S. Picaud1,2,4
1 INSERM U-592, Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, UPMC, Paris, France
2 Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
3 Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France
4 Assistance Publique-Hopitaux de Paris, Paris, France
Glycinergic interplexiform cells provide a feedback signal from the inner retina to the outer retina. To determine if cones receive such a signal, glycine was applied on cultured porcine cone photoreceptors recorded with the patch clamp technique. A minor population of cone photoreceptors was found to generate large currents in response to puff application of glycine. These currents reversed close to the calculated equilibrium potential for chloride ions. These glycine-elicited currents were sensitive to strychnine but not to picrotoxin consistent with the expression of 
–ß-heteromeric glycine receptors. Glycine receptors were also activated by taurine and ß-alanine. The glycine receptor antibody mAb4a labelled a minority of the cone photoreceptors identified by an antibody specific for cone arrestin. Finally, expression of the ß subunit of the glycine receptor was demonstrated by single cell RT-PCR in a similar proportion (
13%) of cone photoreceptors freshly isolated by lectin-panning. The identity of cone photoreceptors was assessed by their specific expression of the cone arrestin mRNA. The population of cone photoreceptors expressing the glycine receptor was not correlated to a specific colour-sensitive subtype as demonstrated by single cell RT-PCR experiments using primers for S opsin, cone arrestin and glycine receptor ß subunit. This glycine receptor expression in a minority of cones defines a new cone population suggesting an unexpected role for glycine in the visual information processing in the outer retina.
(Received 9 November 2005;
accepted after revision 21 December 2005;
first published online 5 January 2006)
Corresponding author S. Picaud: Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, INSERM U592, Hôpital Saint-Antoine, Bâtiment Kourilsky, 184, rue du Faubourg Saint-Antoine, 75 571 Paris cedex 12, France. Email: picaud{at}st-antoine.inserm.fr
Copyright © 2006 The Physiological Society.
