title: Adenosine transporters and receptors: key elements for retinal function and neuroprotection.
abstract: Adenosine is an important neuroactive substance in the central nervous system, including in the retina where subclasses of adenosine receptors and transporters are expressed since early stages of development. Here, we review some evidence showing that adenosine plays important functions in the mature as well as in the developing tissue. Adenosine transporters are divided into equilibrative and concentrative, and the major transporter subtype present in the retina is the ENT1. This transporter is responsible for a bidirectional transport of adenosine and the uptake or release of this nucleoside appears to be regulated by different signaling pathways that are also controlled by activation of adenosine receptors. Adenosine receptors are also key players in retina physiology regulating a variety of functions in the mature and developing tissue. Regulation of excitatory neurotransmitter release and neuroprotection are the main functions played be adenosine in the mature tissue, while regulation of cell survival and neurogenesis are some of the functions played by adenosine in developing retina. Since adenosine is neuroprotective against excitotoxic and metabolic dysfunctions observed in neurological and ocular diseases, the search for adenosine-related drugs regulating adenosine transporters and receptors can be important for advancement of therapeutic strategies against these diseases.
authors.affiliation: Program of Neurosciences, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Dos Santos-Rodrigues
authors.affiliation: Program of Neurosciences, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Mariana R
authors.initials: MR
authors.lastname: Pereira
authors.affiliation: Program of Neurosciences, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Brito
authors.affiliation: Program of Neurosciences, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Nádia A
authors.initials: NA
authors.lastname: de Oliveira
authors.affiliation: Program of Neurosciences, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil. Electronic address: robpaes@vm.uff.br.
authors.forename: Roberto
authors.initials: R
authors.lastname: Paes-de-Carvalho
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000502:physiology*; D002490:Central Nervous System / Q000254:growth & development* / Q000378:metabolism; D006801:Humans; D000066829:Neuroprotection; D033703:Nucleoside Transport Proteins / Q000378:metabolism*; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D033703:Nucleoside Transport Proteins; D018047:Receptors, Purinergic P1; C444719:adenosine transporter; D000241:Adenosine
keywords: Cell survival; Chicken embryo; Development; Equilibrative and concentrative nucleoside transporters; Glial cells; Neurons; Nucleoside; Purified retinal cultures; Signaling pathways