Introduction: Glycine and the gamma-aminobutyric acid are the principal inhibitory neurotransmitters in the vertebrate retina. The inhibitory action of glycine is mediated by the post-synaptic glycine receptor, a chloride-selective channel, constituted by three beta and two alpha subunits (alpha(1)-alpha(4)), which is antagonized by the alkaloid strychnine. In the retina, it is known that all alpha isoforms are expressed at the level of the inner synaptic layer with a very low colocalization. The glycine receptor formed by either alpha1 or alpha(3) shows rapid kinetics, whereas alpha(2) or alpha(4) receptors respond tonically. The use of transgenic mice has allowed the study of the different glycine receptor alpha subunits in the glycinegic neurotransmission of the mammalian retina.
Aim: To describe the participation of the glycine receptor in the inhibitory neurotransmission particularly in the retina.
Development: In this review we describe the experiments that have allowed the localization and the involvement of the alpha subunit isoforms in specific transmission circuits of the vertebrate retina.
Conclusions: The localization of the glycine receptor conformed by different isoforms of the alpha subunit in specific neuronal types, indicate the presence of glycinergic circuits that encode information differently in the retina.