Caffeine alters glutamate-aspartate transporter function and expression in rat retina.
l-Glutamate and l-aspartate are the main excitatory amino acids (EAAs) in the Central Nervous System (CNS) and their uptake regulation is critical for the maintenance of the excitatory balance. Excitatory amino acid transporters (EAATs) are widely distributed among central neurons and glial cells. GLAST and GLT1 are expressed in glial cells, whereas excitatory amino acid transporter 3/excitatory amino acid carrier 1 (EAAT3/EAAC1) is neuronal. Different signaling pathways regulate glutamate uptake by modifying the activity and expression of EAATs. In the present work we show that immature postnatal day 3 (PN3) rat retinas challenged by l-glutamate release [3H]-d-Aspartate linked to the reverse transport, with participation of NMDA, but not of non-NMDA receptors. The amount of [3H]-d-Aspartate released by l-glutamate is reduced during retinal development. Moreover, immature retinae at PN3 and PN7, but not PN14, exposed to a single dose of 200 or 500μM caffeine or the selective A2A receptor (A2AR) antagonist 100nM ZM241385 decreased [3H]-d-Aspartate uptake. Caffeine also selectively increased total expression of EAAT3 at PN7 and its expression in membrane fractions. However, both EAAT1 and EAAT2 were reduced after caffeine treatment in P2 fraction. Addition of 100nM DPCPX, an A1 receptor (A1R) antagonist, had no effect on the [3H]-d-Aspartate uptake. [3H]-d-Aspartate release was dependent on both extracellular sodium and Dl-TBOA, but not calcium, implying a transporter-mediated mechanism. Our results suggest that in the developing rat retina caffeine modulates [3H]-d-Aspartate uptake by blocking adenosine A2AR.
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: dudadefreitas@ig.com.br.
Adriana Pinto
AP
de Freitas
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: ferreiradanielle@id.uff.br.
Danielle Dias Pinto
DD
Ferreira
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: arletefernandes@id.uff.br.
Arlete
A
Fernandes
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: romartins@id.uff.br.
Robertta Silva
RS
Martins
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: vladimirppbm@gmail.com.
Vladimir Pedro Peralva
VP
Borges-Martins
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: msathler@id.uff.br.
Matheus Figueiredo
MF
Sathler
Laboratorio de Neurofisiologia Molecular, Departamento de Fisiologia, Faculdade de Medicina de Ribeirao Preto, Universidade de São Paulo, Ribeirão Preto, Brazil. Electronic address: msp_biomed@yahoo.com.br.
Maurício
M
Dos-Santos-Pereira
Laboratório de Neurobiologia Celular, Departamento de Neurobiologia, Instituto de Biologia, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: robpaes@vm.uff.br.
Roberto
R
Paes-de-Carvalho
Laboratório de cultura de tecidos Hertha Meyer, Departamento de Neurobiologia, Instituto de Biologia, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: egiestal@vm.uff.br.
Elizabeth
E
Giestal-de-Araujo
Laboratório de Neuroquímica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal de Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: ramreis@biof.ufrj.br.
Ricardo Augusto
RA
de Melo Reis
Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil. Electronic address: kubrusly@vm.uff.br.
Regina Celia Cussa
RC
Kubrusly
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D050491:Glutamate Plasma Membrane Transport Proteins / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D050491:Glutamate Plasma Membrane Transport Proteins; D001224:Aspartic Acid; D002110:Caffeine; D018698:Glutamic Acid; D012964:Sodium
A2A receptor; NMDA receptors; adenosine; glutamate transport; retina