Identification of zebrafish A2 adenosine receptors and expression in developing embryos.

The A2A adenosine receptor (AdR) subtype has emerged as an attractive target in the pursuit of improved therapy for Parkinson's disease (PD). This report focuses on characterization of zebrafish a2 AdRs. By mining the zebrafish EST and genomic sequence databases, we identified two zebrafish a2a (adora2a.1 and adora2a.2) genes and one a2b (adora2b) AdR gene. Sequence comparisons indicate that the predicted zebrafish A2 AdR polypeptides share 62-74% amino acid identity to mammalian A2 AdRs. We mapped the adora2a.1 gene to chromosome 8, the adora2a.2 gene to chromosome 21, and the adora2b gene to chromosome 5. Whole mount in situ hybridization analysis indicates zebrafish a2 AdR genes are expressed primarily within the central nervous system (CNS). Zebrafish are known to be sensitive to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a neurotoxin that causes selective loss of dopaminergic neurons and PD-like symptoms in humans as well as in animal models. Here we show that caffeine, an A2A AdR antagonist, is neuroprotective against the adverse effects of MPTP in zebrafish embryos. These results suggest that zebrafish AdRs may serve as useful targets for testing novel therapeutic strategies for the treatment of PD.

[1]  Jan Kaslin,et al.  Neurochemical and behavioural changes in zebrafish Danio rerio after systemic administration of 6‐hydroxydopamine and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine , 2003, Journal of neurochemistry.

[2]  M. Schwarzschild,et al.  Neuroprotection by Caffeine and A2A Adenosine Receptor Inactivation in a Model of Parkinson's Disease , 2001, The Journal of Neuroscience.

[3]  M. Williams,et al.  Direct autoradiographic localization of adenosine A2 receptors in the rat brain using the A2-selective agonist, [3H]CGS 21680. , 1989, European journal of pharmacology.

[4]  M. Morelli,et al.  New therapies for the treatment of Parkinson's disease: adenosine A2A receptor antagonists. , 2005, Life sciences.

[5]  E. Oztaş,et al.  Novel neuroprotection by caffeine and adenosine A2A receptor antagonists in animal models of Parkinson's disease , 2006, Journal of the Neurological Sciences.

[6]  V. Korzh,et al.  Zebrafish embryos are susceptible to the dopaminergic neurotoxin MPTP , 2005, The European journal of neuroscience.

[7]  P. Ma.  Catecholaminergic systems in the zebrafish. IV. Organization and projection pattern of dopaminergic neurons in the diencephalon , 2003, The Journal of comparative neurology.

[8]  K. Fuxe,et al.  Targeting adenosine A2A receptors in Parkinson's disease , 2006, Trends in Neurosciences.

[9]  R. Cunha,et al.  Adenosine as a neuromodulator and as a homeostatic regulator in the nervous system: different roles, different sources and different receptors , 2001, Neurochemistry International.

[10]  Erwan Bezard,et al.  Novel pharmacological targets for the treatment of Parkinson's disease , 2006, Nature Reviews Drug Discovery.

[11]  Langston Jw,et al.  Parkinson's disease in a chemist working with 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine. , 1983 .

[12]  R. Bhidayasiri,et al.  Motor complications in Parkinson disease: Clinical manifestations and management , 2008, Journal of the Neurological Sciences.

[13]  K. Jacobson,et al.  Adenosine receptors as therapeutic targets , 2006, Nature Reviews Drug Discovery.

[14]  M. Okusa.  A(2A) adenosine receptor: a novel therapeutic target in renal disease. , 2002, American journal of physiology. Renal physiology.

[15]  J. Mullikin,et al.  SSAHA: a fast search method for large DNA databases. , 2001, Genome research.

[16]  P. Svenningsson,et al.  Adenosine A2A Receptors are Colocalized with and Activate Golf in Rat Striatum , 2000 .

[17]  A. Rubinstein,et al.  Neuroprotection of MPTP-induced toxicity in zebrafish dopaminergic neurons. , 2005, Brain research. Molecular brain research.

[18]  Su Guo,et al.  Sensitivity of zebrafish to environmental toxins implicated in Parkinson's disease. , 2004, Neurotoxicology and teratology.

[19]  P. Svenningsson,et al.  Cellular expression of adenosine A2A receptor messenger RNA in the rat central nervous system with special reference to dopamine innervated areas , 1997, Neuroscience.

[20]  B. Thisse,et al.  High-resolution in situ hybridization to whole-mount zebrafish embryos , 2007, Nature Protocols.

[21]  E. Oztaş,et al.  Neuroprotection by caffeine and more specific A2A receptor antagonists in animal models of Parkinson’s disease , 2003, Neurology.

[22]  Wolfgang Driever,et al.  Dopamine transporter expression distinguishes dopaminergic neurons from other catecholaminergic neurons in the developing zebrafish embryo , 2001, Mechanisms of Development.

[23]  B. Fredholm,et al.  Comparison of the potency of adenosine as an agonist at human adenosine receptors expressed in Chinese hamster ovary cells. , 2001, Biochemical pharmacology.

[24]  J. Devereux,et al.  A comprehensive set of sequence analysis programs for the VAX , 1984, Nucleic Acids Res..

[25]  B. Paw,et al.  Characterization of whole genome radiation hybrid mapping resources for non-mammalian vertebrates. , 1998, Nucleic acids research.

[26]  B. Fredholm,et al.  Actions of adenosine at its receptors in the CNS: insights from knockouts and drugs. , 2005, Annual review of pharmacology and toxicology.

[27]  J. Felsenstein.  Evolutionary trees from DNA sequences: A maximum likelihood approach , 2005, Journal of Molecular Evolution.

[28]  T. Sherer,et al.  Animal models of Parkinson's disease. , 2002, BioEssays : news and reviews in molecular, cellular and developmental biology.

[29]  W. Fitch,et al.  Construction of phylogenetic trees. , 1967, Science.