title: Coexpression of several types of metabotropic nucleotide receptors in single cerebellar astrocytes.
abstract: We have examined the expression of mRNA for several P2Y nucleotide receptors by northern blot analysis in purified type 1 cerebellar astrocyte cultures. These results suggest that different P2Y subtypes could be responsible for ATP metabotropic calcium responses in single type 1 astrocytes. To identify these subtypes we have studied the pharmacological profile of ATP calcium responses using fura-2 microfluorimetry. All tested astrocytes responded to ATP and UTP stimulations evoking similar calcium transients. Most astrocytes also responded to 2-methylthioATP and ADP challenges. The agonist potency order was 2-methylthioATP > ADP > ATP = UTP. Cross-desensitization experiments carried out with ATP, UTP, and 2-methylthioATP showed that 2-methylthioATP and UTP interact with different receptors, P2Y(1) and P2Y(2) or P2Y(4). In a subpopulation of type 1 astrocytes, ATP prestimulation did not block UTP responses, and UDP elicited clear intracellular Ca(2+) concentration responses at very low concentrations. 2-MethylthioATP and UTP calcium responses exhibited different sensitivity to pertussis toxin and different inhibition patterns in response to P2 antagonists. The P2Y(1)-specific antagonist N:(6)-methyl-2'-deoxyadenosine 3', 5'-bisphosphate (MRS 2179) specifically blocked the 2-methylthio-ATP responses. We can conclude that all single astrocytes coexpressed at least two types of P2Y metabotropic receptors: P2Y(1) and either P2Y(2) or P2Y(4) receptors. Moreover, 30-40% of astrocytes also coexpressed specific pyrimidine receptors of the P2Y(6) subtype, highly selective for UDP coupled to pertussis-toxin insensitive G protein.
authors.affiliation: Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
authors.forename: A I
authors.initials: AI
authors.lastname: Jiménez
authors.forename: E
authors.initials: E
authors.lastname: Castro
authors.forename: D
authors.initials: D
authors.lastname: Communi
authors.forename: J M
authors.initials: JM
authors.lastname: Boeynaems
authors.forename: E G
authors.initials: EG
authors.lastname: Delicado
authors.forename: M T
authors.initials: MT
authors.lastname: Miras-Portugal
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007424:Intracellular Fluid / Q000378:metabolism; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis*; D013268:Stimulation, Chemical; D013498:Suramin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D011493:Protein Kinase C; D002118:Calcium; D014544:Uridine Triphosphate; C008501:2-methylthio-ATP