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Expression of A1 adenosine receptors in the developing avian retina: in vivo modulation by A 2A receptors and endogenous adenosine
Author(s) -
Brito Rafael,
Pereira Mariana Rodrigues,
PaesdeCarvalho Roberto,
Calaza Karin da Costa
Publication year - 2012
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2012.07909.x
Subject(s) - cgs 21680 , adenosine , adenosine receptor , adenosine a1 receptor , agonist , receptor , adenosine a2b receptor , endocrinology , medicine , chemistry , adenosine a2a receptor , biology , biochemistry
Abstract Little is known about the mechanisms that regulate the expression of adenosine receptors during CNS development. We demonstrate here that retinas from chick embryos injected in ovo with selective adenosine receptor ligands show changes in A1 receptor expression after 48 h. Exposure to A1 agonist N 6 ‐cyclohexyladenosine ( CHA ) or antagonist 8‐Cyclopentyl‐1, 3‐dipropylxanthine ( DPCPX ) reduced or increased, respectively, A1 receptor protein and [ 3 H] DPCPX binding, but together, CHA + DPCPX had no effect. Interestingly, treatment with A 2A agonist 3‐[4‐[2‐[[6‐amino‐9‐[(2R,3R,4S,5S)‐5‐(ethylcarbamoyl)‐3,4‐dihydroxy‐oxolan‐2‐yl]purin‐2‐yl]amino] ethyl]phenyl] propanoic acid ( CGS 21680) increased A1 receptor protein and [ 3 H] DPCPX binding, and reduced A 2A receptors. The A 2A antagonists 7‐(2‐phenylethyl)‐5‐amino‐2‐(2‐furyl)‐pyrazolo‐[4,3‐e]‐1,2,4‐trizolo[1,5‐c] pyrimidine ( SCH 58261) and 4‐(2‐[7‐amino‐2‐[2‐furyl][1,2,4]triazolo[2,3‐a][1,3,5]triazo‐5‐yl‐amino]ethyl)phenol ( ZM 241385) had opposite effects on A1 receptor expression. Exposure to CGS 21680 + CHA did not change A1 receptor levels, whereas CHA + ZM 241385 or CGS 21680 + DPCPX had no synergic effect. The blockade of adenosine transporter with S‐(4‐nitrobenzyl)‐6‐thioinosine ( NBMPR ) also reduced [ 3 H] DPCPX binding, an effect blocked by DPCPX , but not enhanced by ZM 241385. [ 3 H] DPCPX binding kinetics showed that treatment with CHA reduced and CGS 21680 increased the Bmax, but did not affect Kd values. CHA , DPCPX , CGS 21680, and ZM 241385 had no effect on A1 receptor mRNA . These data demonstrated an in vivo regulation of A1 receptor expression by endogenous adenosine or long‐term treatment with A1 and A 2A receptors modulators.